WO2019139100A1 - Method for producing piezoelectric film - Google Patents

Method for producing piezoelectric film Download PDF

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Publication number
WO2019139100A1
WO2019139100A1 PCT/JP2019/000593 JP2019000593W WO2019139100A1 WO 2019139100 A1 WO2019139100 A1 WO 2019139100A1 JP 2019000593 W JP2019000593 W JP 2019000593W WO 2019139100 A1 WO2019139100 A1 WO 2019139100A1
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Prior art keywords
niobium
film
alkali
tantalate
substrate
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PCT/JP2019/000593
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French (fr)
Japanese (ja)
Inventor
舟窪　浩
明紀 舘山
良晴 伊東
荘雄 清水
折野　裕一郎
黒澤　実
内田　寛
白石　貴久
賢紀 木口
熊田　伸弘
Original Assignee
国立大学法人東京工業大学
学校法人上智学院
国立大学法人東北大学
国立大学法人山梨大学
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Application filed by 国立大学法人東京工業大学, 学校法人上智学院, 国立大学法人東北大学, 国立大学法人山梨大学 filed Critical 国立大学法人東京工業大学
Priority to JP2019564746A priority Critical patent/JPWO2019139100A1/en
Publication of WO2019139100A1 publication Critical patent/WO2019139100A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G35/00—Compounds of tantalum
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
    • H10N30/074—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
    • H10N30/077—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing by liquid phase deposition
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/40—Piezoelectric or electrostrictive devices with electrical input and electrical output, e.g. functioning as transformers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/853—Ceramic compositions

Definitions

  • the present invention relates to a method for producing a piezoelectric film, and more particularly to a method for producing a niobium / tantalate piezoelectric film by a hydrothermal synthesis method.
  • Piezoelectric materials are widely used for actuator elements, pressure sensors, ultrasonic transducers and the like, and recently, application to vibration power generation devices has also attracted attention.
  • lead zirconate titanate (PZT) is the mainstream as the piezoelectric material currently used, lead-free piezoelectric materials are being sought from the viewpoint of environmental load, and among various lead-free piezoelectric materials
  • An alkali niobium / tantalate piezoelectric material having a perovskite structure is a strong candidate for the above application because it has excellent piezoelectric properties, mechanical bondability and high Curie temperature.
  • the present invention is a method of using a hydrothermal synthesis method capable of low-temperature film formation having the above-mentioned advantages, wherein the niobium / tantalate alkali type piezoelectric film enables thickening of the niobium / tantalate type piezoelectric film. It is an object of the present invention to provide a method of manufacturing the above, and to provide a thick film niobium / tantalate alkali based piezoelectric or pyroelectric film and a piezoelectric or pyroelectric element and a functional device using the same.
  • the present invention immerses and heats a substrate in a water-containing solvent containing alkali hydroxide and amorphous niobium / tantalum oxide in a reaction vessel. Then, under pressure, a niobium / tantalate alkali-based film having a perovskite crystal structure is deposited on a substrate to complete the above-described object.
  • a niobium / tantalate alkali-based film having a perovskite crystal structure is deposited on a substrate to complete the above-described object.
  • An alkali niobium / tantalate based alignment film having a film thickness from the above to mm order and a novel piezoelectric or pyroelectric element and functional device using the same are provided.
  • the present invention constitutes a breakthrough in thickening of a niobium / tantalate alkali type alignment film.
  • a method of producing a niobium / tantalate alkali based film of the present invention will be exemplified below by exemplifying some of the representative embodiments or preferred embodiments of the first aspect of the present invention (hereinafter also referred to simply as the present invention).
  • the batch process may be repeated, but the film thickness of the niobium / tantalate alkali type film deposited in one batch process is 1 ⁇ m or more, 3 ⁇ m or more, 10 ⁇ m or more, 15 ⁇ m or more, and further 20 ⁇ m or more. Can. This film thickness can be further increased by increasing the size of the reaction apparatus.
  • the niobium / tantalate alkali type film is deposited, and the film thickness of the obtained niobium / tantalate alkali type film is 3 ⁇ m or more, 10 ⁇ m or more, 20 ⁇ m or more, It can be more than.
  • the niobium / tantalate alkali type film obtained by the manufacturing method of the present invention can preferably have a size of 60 ⁇ m or more, 70 ⁇ m or more, 100 ⁇ m or more, 140 ⁇ m or more, 150 ⁇ m or more, 200 ⁇ m or more, 300 ⁇ m or more, and further 1 mm.
  • the upper limit of the film thickness of the niobium / tantalate alkali type film may be determined depending on the application and economy, but may be several mm or less, 1 mm or less, 500 ⁇ m or less, 400 ⁇ m or less, 300 ⁇ m or less, for example.
  • the substrate may have a surface including a flat surface and / or a curved surface.
  • the amount of the niobium / tantalate based alkali film deposited on the substrate is 4 mmol or more based on 1 mol of the niobium / tantalum based oxide consumed, Or it can be 0.5 mass% or more of the niobium / tantalum-based oxide consumed. Furthermore, it may be 4.0% by mass or more and 20% by mass or more.
  • the molar ratio of the alkali hydroxide to the amorphous niobium / tantalum based oxide is, for example, 1: 1.0 ⁇ 10 ⁇ 4 to 1: 1. It may be 0 ⁇ 10 5 or even 1: 1.0 ⁇ 10 ⁇ 2 to 1: 1.0 ⁇ 10 4 .
  • the alkali hydroxide may be potassium hydroxide and / or sodium hydroxide and / or lithium hydroxide, in particular potassium hydroxide and / or sodium hydroxide.
  • the molar ratio of potassium hydroxide to the total of potassium hydroxide and sodium hydroxide may be 0.0 to 1.0, further 0.6 to 1.0 or 0.75 to 1.0.
  • the molar ratio of lithium hydroxide to the total of potassium hydroxide, sodium hydroxide and lithium hydroxide may be from 0 to 0.1.
  • the concentration of the water-containing solvent or the alkali hydroxide in the water is, for example, 0.1 to 30 mol / L, and further 0.1 to 20 mol / L. May be there.
  • the substrate may have a perovskite crystal structure.
  • the substrate may be made of a material selected from semiconductors, metals, plastics and ceramics, and the substrate may have a buffer layer of a perovskite crystal structure.
  • the substrate may be a conductive substrate.
  • the niobium / tantalate alkali type film further comprises an oxide selected from CaO, CuO, MnO 2 , Sb 2 O 3 , BaO, ZrO 2 and TiO 2.
  • oxides are oxides that can be solid-solved in an alkali of niobium / tantalate, and may be a solid solution in the niobium / tantalate alkali film, but may be a mixture.
  • the reaction vessel may be a sealed vessel, and the temperature in the reaction vessel may be heated to a temperature of 50 to 300.degree.
  • the reaction vessel may be a sealed vessel, and the inside of the reaction vessel may be heated using a microwave.
  • the niobium / tantalate alkali type film can contain crystals uniaxially or epitaxially oriented.
  • the niobium / tantalate alkali type film can be self-polarized (the polarization directions are aligned without polarization treatment).
  • the niobium / tantalate alkali type film can be annealed at a temperature of 100 to 750 ° C. after being taken out of water.
  • the niobium / tantalate alkali type film can be a piezoelectric film.
  • the film may be a uniaxially or epitaxially oriented niobium / tantalate alkali based film produced by the above-mentioned production method.
  • a (Nb 1-x Ta x ) O 3 (wherein A is one or two or more alkali metals, and the ratio of two or more alkali metals is arbitrary.
  • the niobium / tantalate alkali type film of the second aspect of the present invention (hereinafter, also simply referred to as the present invention), the niobium / tantalate alkali type film is self-polarized (the polarization directions are aligned without polarization treatment). Can be.
  • the niobium / tantalate alkali type film of the present invention can be formed on a substrate having a perovskite crystal structure.
  • the substrate can have a conductive surface in contact with the niobium / tantalate alkali type film.
  • the base includes a material selected from semiconductors, metals, plastics, and ceramics, and a base having a buffer layer of a perovskite structure between the material and the niobium / tantalate alkali type film.
  • a material selected from semiconductors, metals, plastics, and ceramics and a base having a buffer layer of a perovskite structure between the material and the niobium / tantalate alkali type film.
  • a functional device utilizing piezoelectric characteristics
  • the piezoelectric device includes a piezoelectric device including the above-mentioned niobium / tantalate alkali type film and an electrode
  • the functional device is a medical device.
  • the functional device may be selected from an ultrasonic probe, an ultrasonic transmitter, an ultrasonic sensor, a pyroelectric generator, a vibration generator, and an actuator.
  • the functional device of the present invention can include a transducer for an ultrasonic probe capable of transmitting or receiving ultrasonic waves of 2 to 100 MHz.
  • the functional device of the present invention can be an ultrasonic imaging device capable of diagnostic imaging of an area within a depth of 20 mm below the surface of the skin using a transducer for an ultrasonic probe.
  • the functional device of the present invention can be a medical device capable of performing medical treatment on human tissue using an ultrasonic probe transducer.
  • the functional device of the present invention can be a power generator having an output power density of 1 ⁇ W ⁇ G ⁇ 2 ⁇ mm ⁇ 3 or more at a resonant frequency of 200 Hz or less.
  • a niobium / tantalate alkali based film of the present invention According to the method for producing a niobium / tantalate alkali based film of the present invention, a niobium / tantalum having the same crystallinity and piezoelectric properties as conventionally obtained niobium / tantalate alkali based films using a hydrothermal synthesis method
  • the film thickness obtained can be increased and the deposition efficiency can be improved under the same manufacturing conditions as compared with the film thickness that can be formed from an acid alkali film and formed from conventional starting materials.
  • the orientation of the obtained niobium / tantalate alkali type film can be improved.
  • an alkali niobium / tantalate based alignment film having a film thickness not provided conventionally is provided. Furthermore, for new applications (for example, medical applications such as diagnostic imaging in the vicinity of the skin surface of the human body) utilizing its piezoelectric or pyroelectric properties, such as piezoelectric or pyroelectric elements having lower frequency and higher output than conventional ones. A functional device is provided.
  • FIG. 1 is a schematic cross-sectional view of an example of a reaction apparatus used in the method for producing a niobium / tantalate alkali based film of the present invention.
  • FIG. 2 is a cross-sectional view showing a schematic piezoelectric element 10.
  • FIG. 3 schematically shows an example of the ultrasonic probe 1.
  • FIG. 4 schematically shows an example of the pyroelectric power generation system 10.
  • FIGS. 5 (a) and 5 (b) are X-ray diffraction charts of amorphous Nb 2 O 5 and crystalline Nb 2 O 5 used as raw materials in Examples and Comparative Examples.
  • FIG. 6 is an X-ray diffraction chart of the KNN films obtained in Example 1 and Comparative Example 1.
  • FIGS. 7A and 7B are graphs showing the relationship between the film thickness of the KNN films obtained in Examples 1 and 2 and Comparative Examples 1 and 2 and the reaction time.
  • FIG. 8 is a SEM photograph of the microstructures of the KNN films obtained in Example 1 and Comparative Example 1.
  • FIG. 9 is a SEM photograph obtained by observing the fine structure (plane) and the film thickness (cross section) of the KNN films obtained in Example 1 and Comparative Example 1.
  • (A) and (b) are KNN films with a film thickness of 5 ⁇ m obtained in Comparative Example 1
  • (c) and (d) are KNN films with a film thickness of 10 ⁇ m obtained in Example 1
  • (a) and (b) In (c), the microstructure (plane) is observed, and in (b) and (d), the film thickness (cross section) is observed.
  • FIG. 10 is a graph showing the correspondence between the alkali ratio of the raw material in the KNN film obtained in the example and the comparative example and the alcal ratio of the KNN film.
  • FIG. 11 is a graph showing the correspondence between the alkali ratio of the raw material in the KNN film obtained in the example and the comparative example and the film thickness of the KNN film.
  • FIG. 12 shows a SEM cross-sectional photograph of the KNN film obtained in Example 8.
  • FIG. 13 is another graph showing the relationship between the film thickness of the KNN films obtained in Examples 1 and 2 and Comparative Examples 1 and 2 and the reaction time.
  • FIG. 14 is a graph showing the relative dielectric constants and dielectric losses of the piezoelectric elements of the example and the comparative example.
  • FIG. 15 is a graph showing dielectric polarization hysteresis curves of the piezoelectric elements of the example and the comparative example.
  • FIG. 16 is a graph showing the electric field induced strain of the piezoelectric element of the example and the comparative example.
  • FIG. 18 is a graph showing the relationship between the annealing temperature and the dielectric polarization hysteresis curve in the piezoelectric elements of the example and the comparative example. After deposition, (b) to (e) have different annealing temperatures.
  • FIG. 19 is a graph showing the relationship between the annealing temperature and the electric field induced strain characteristic in the piezoelectric elements of the example and the comparative example. After deposition, (b) to (e) have different annealing temperatures.
  • FIG. 20 (a) and 20 (b) are graphs showing the relationship between the annealing temperature and the relative dielectric constant and the dielectric loss in the piezoelectric element of the comparative example and the example, respectively.
  • FIG. 21 shows the thickness of the KNN film obtained in Example 14 in comparison with the case of using crystalline niobium oxide.
  • 22 (a) and 22 (b) are X-ray diffraction charts and SEM photographs of crystalline tantalum oxide
  • FIGS. 22 (c) and 22 (d) are X-ray diffraction charts of amorphous tantalum oxide obtained in Example 16. And a SEM photograph.
  • FIG. 23 (a) shows X-ray diffraction charts of the KNN films obtained in Example 18 and Comparative Example 11, and FIG.
  • FIG. 23 shows the KNN films obtained in Example 1 and Comparative Example 1.
  • the X-ray diffraction chart is shown.
  • FIG. 24 shows the results of X-ray diffraction of the KNN film obtained in Example 19.
  • FIG. 25 shows the Nb / (Nb + Ta) ratio and the K / (K + Na) ratio of the KNNT alignment film obtained in Example 20.
  • FIG. 26 shows the piezoelectric characteristics of the KNLNT film obtained in Example 22.
  • FIG. 27 shows PE hysteresis curves of piezoelectric elements using a KNN film of as depo. And a KNN film heat-treated at 600 ° C., and e 31, f with respect to an electric field.
  • FIG. 28 shows the e 31, f with respect to the polarization treatment electric field of the piezoelectric element using the KNN film of as depo. And the KNN film heat-treated at 600 ° C.
  • FIG. 29 shows the relationship between the film thickness of e 31 and f of the KNN film.
  • FIG. 30 shows AFM (d 33 ) of a piezoelectric element using a KNN film of as depo. And a KNN film heat-treated at 600 ° C.
  • the upper part of FIG. 31 shows the change of the shift amount of the PE hysteresis curve when the heat treatment temperature is changed. As the heat treatment temperature increases from the as depo. KNN film, the shift amount decreases.
  • FIG. 31 shows the relationship between the amount of water in the membrane and the shift amount of the PE hysteresis curve.
  • FIG. 32 shows the relationship between the amount of OH ⁇ in the lattice, (a) the film-forming temperature and (b) the water-containing solvent.
  • FIG. 34 shows the change in the power generation characteristics observed in Example 26, and the change in output power (broken line) calculated from the basic characteristics of the piezoelectric element.
  • FIG. 34 schematically shows a microwave-heatable reactor.
  • a substrate is immersed in a water-containing solvent containing an alkali hydroxide and an amorphous niobium / tantalum oxide in a reaction vessel, heated and pressed, on the substrate.
  • the niobium / tantalate alkali-based film having a perovskite crystal structure
  • the niobium / tantalum-based oxide has an average composition formula (Nb 1-x Ta x ) 2 O 5 (wherein 0 ⁇ x Niobium oxide represented by ⁇ 1), a single body of tantalum oxide, a solid solution or a mixture thereof, which may be a hydrate
  • the niobium / tantalate alkali based film is A (Nb 1 -x Niobium represented by Ta x ) O 3 (wherein, A represents one or more alkali metals, and the ratio of two or more alkali metals is arbitrary, and 0 ⁇ x ⁇ 1).
  • A represents one or more alkali metals, and the ratio of two or more alkali metals is arbitrary, and 0 ⁇ x ⁇ 1).
  • With crystals containing alkali metal tantalate In the production method of a niobi
  • FIG. 1 schematically shows a cross section of an example of a reaction apparatus used in the method for producing a niobium / tantalate alkali based film of the present invention.
  • a water-containing solvent here, water 2 is contained in a closed reaction vessel 1, and in the water 2, an alkali hydroxide such as sodium hydroxide or potassium hydroxide is dissolved.
  • Amorphous niobium / tantalum oxide 3 is added as a powder in this example.
  • the base 4 is suspended from above in the reaction vessel 1 and immersed in water (alkaline aqueous solution) 2.
  • the reaction vessel is a closed vessel that contains a water-containing solvent, an alkali hydroxide and an amorphous niobium / tantalum oxide in the water-containing solvent, and can heat and pressurize the inside of the reaction vessel. It can be a container called an autoclave.
  • the reaction container also has a structure capable of immersing one or more substrates in the water-containing solvent in the container, but the method of holding the substrates is not limited, and for example, attached to the fixture 5 installed on the lid of the container Can be a structure.
  • the direction, etc., of the substrate 4 to be immersed in the water-containing solvent can be set as appropriate, such as vertical or horizontal.
  • the water-containing solvent used in the present invention is a solvent containing water, and may be a mixed solvent of water and an organic solvent in addition to water, but ion-exchanged water is particularly preferable.
  • an organic solvent to be used by mixing with water an organic solvent which is soluble or miscible with water, such as alcohol, ketone, carboxylic acid, ether or the like is preferable.
  • the alkali hydroxide used in the present invention may be any of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide and francium hydroxide, but sodium hydroxide, potassium hydroxide and lithium hydroxide And mixtures of sodium hydroxide and potassium hydroxide, and mixtures of sodium hydroxide, potassium hydroxide and lithium hydroxide. It is preferable to include both potassium hydroxide and sodium hydroxide as the alkali hydroxide in view of the improvement of the piezoelectric characteristics, the improvement of the insulating property, and the improvement of the deposition rate.
  • the molar ratio of potassium hydroxide to the total of sodium hydroxide and potassium hydroxide ([KOH] / ([KOH] + [NaOH])) Can range from 0.0 to 1.0.
  • the alkali molar ratio of the raw material and the alkali molar ratio of the product are not in direct proportion, but show a unique proportion relationship in which the alkali molar ratio of the product sharply increases in a specific range.
  • the alkali molar ratio of the product is in a relation of monotonously increasing.
  • an increase in film thickness according to the present invention could be observed in the entire range of 0.0 to 1.0 of the above-mentioned alkali molar ratio of the raw material.
  • the molar ratio of sodium hydroxide to potassium hydroxide ([KOH] / ([KOH] + [NaOH])) of the raw material is in the range of 0.6 to 1.0, and further in the range of 0.75 to 1.0 Is preferred. Within these preferable ranges, the film thickness of the niobium / tantalate alkali type film can be particularly large (see FIG. 10).
  • the above-mentioned alkali molar ratio of the raw material is, for example, in the range of 0.0 to 1.0, and further in the range of 0.6 to 1.0, and particularly 0.75 to 0.95, It is preferable to use for the application of an actuator.
  • the molar ratio ([KOH] / ([KOH] + [NaOH])) of sodium hydroxide and potassium hydroxide is 0.6 to 1.0. It is more preferable that the range is from 0.75 to 1.0.
  • the molar ratio of lithium hydroxide to the total of sodium hydroxide, potassium hydroxide and lithium hydroxide may be, for example, 0 to 0.5, further 0 to 0.1, 0 to 0.05, 0 to 0.03.
  • the concentration of alkali hydroxide in water used in the present invention may be 0.1 to 30 mol / L, 0.1 to 20 mol / L, 1 to 10 mol / L, particularly 3 to 8 mol / L.
  • the upper limit value and the lower limit value of these ranges may be combined independently.
  • the concentration of the alkali hydroxide is within these ranges, the reactivity with the niobium / tantalum oxide becomes high, the nucleation and deposition rate of the niobium / tantalate alkali type film can be high, and the film thickness can be increased. it is conceivable that.
  • the alkali hydroxide may be dissolved in water in the reaction vessel (in the following description, water may be a water-containing solvent) at the time of reaction (heating / pressurization). It may be previously dissolved in the water to be injected, may be added to the water contained in the reaction vessel to be dissolved, or a combination thereof.
  • the amorphous niobium / tantalum-based oxide used in the first aspect of the present invention has an average composition formula of (Nb 1-x Ta x ) 2 O 5 (wherein 0 ⁇ x ⁇ 1). Oxides, solid solutions or mixtures thereof, which may be hydrates.
  • the niobium / tantalum-based oxide used in the first aspect of the present invention is characterized in that it is not crystalline but is amorphous.
  • the reason is unclear, but, surprisingly, the case where the crystalline is used and
  • the inventors have found that the film thickness and the deposition efficiency of the niobium / tantalate alkali type film which can be deposited on the substrate under the same conditions as the others are significantly improved (see Examples).
  • the amorphous nature of the niobium / tantalum-based oxide is confirmed by the fact that the characteristic peak of the niobium / tantalum-based oxide is not recognized by X-ray diffraction.
  • the absence of a characteristic peak of the niobium / tantalum-based oxide means that a halo is present without a clear peak from the result of powder X-ray diffraction measurement (see FIG. 5).
  • Amorphous niobium / tantalum-based oxides are described, for example, in N. Kumada et al., “Hydrothermal synthesis of NaNbO 3 --morphology change by starting compounds--, Journal of the Chemical Society of Japan 119 (6) 483-485. It can be manufactured by the manufacturing method described in 2011. That is, an amorphous niobium / tantalum-based oxide is heated and melted by adding alkali such as potassium carbonate to niobium oxide / tantalum in a container and cooling them.
  • alkali such as potassium carbonate
  • the resulting (white) powder or lump is dissolved in pure water, the undissolved one is removed with filter paper, and an aqueous solution of acid such as HNO 3 is added to the filtrate to precipitate the (white) powder.
  • the powder is filtered, washed with distilled water, and dried.
  • the amorphous niobium / tantalum oxide synthesized by this method is a hydrate, but when it is allowed to stand at 200 ° C. for 24 hours using a drier, for example. , The obtained powder is non-hydrated (In addition to confirmation by X-ray diffraction, the same loss as thermogravimetric analysis is also confirmed).
  • the crystalline niobium / tantalum oxide used as a raw material is melted, so it is not necessary to be a solid solution, and a mixture of niobium oxide and tantalum oxide may be used. .
  • the amorphous niobium / tantalum-based oxide added to the inside of the reaction vessel has no difference between the solid solution and the mixture as long as the average composition for realizing the intended composition of the niobium / tantalate alkali type film is satisfied.
  • a mixture of niobium oxide and tantalum oxide is preferably used.
  • the addition amount of the amorphous niobium / tantalum oxide is such that the molar ratio of alkali hydroxide to the amorphous niobium / tantalum oxide is 1: 1.0 ⁇ 10 ⁇ 4 to 1: 1.
  • the amount may be 0 ⁇ 10 5 or even 1: 1.0 ⁇ 10 ⁇ 2 to 1: 1.0 ⁇ 10 4 .
  • the addition amount of the amorphous niobium / tantalum oxide is larger than the lower limit value of this range, it is preferable because a certain amount of niobium / tantalum dissolved in the solution can be present, and the amount is smaller than the upper limit value of this range It is preferred that the dissolved niobium / tantalum be present in solution without homogeneous nucleation.
  • the above molar ratio may be 1: 1.0 ⁇ 10 ⁇ 3 to 1: 1.0 ⁇ 10 5 or even 1: 1.0 ⁇ 10 2 to 1: 1.0 ⁇ 10 5 .
  • Amorphous niobium / tantalum-based oxides are preferable because they are powdery, because they have high solubility (reactivity with alkaline aqueous solution) in alkaline aqueous solution when heated and pressurized, but they are other shapes such as bulk. May be
  • the amorphous niobium / tantalum oxide may be previously contained in a reaction container, and water (or aqueous alkali solution) may be added to the reaction container, or water (or aqueous alkali solution) may be charged in the reaction container. Alternatively, an amorphous niobium / tantalum oxide may be added thereto.
  • the obtained film has the formula A (Nb 1-x Ta x ) O 3 (wherein A is one or two or more alkali metals, and the ratio of two or more alkali metals) Is a crystal containing an alkali of niobium / tantalate represented by 0 ⁇ x ⁇ 1), but CaO, CuO, MnO 2 , Sb 2 O 3 , BaO, ZrO 2 , TiO 2 etc. And oxides of the same can be included, thereby improving properties such as piezoelectric properties.
  • These oxides are mainly incorporated as a solid solution and / or a mixture in the niobium / tantalate alkali type membrane after the hydrothermal synthesis by being added to the aqueous alkali solution.
  • a composite oxide may be formed.
  • the addition amount of these oxides is not particularly limited as long as it is an amount to improve the properties of the niobium / tantalate alkali based film, and although it depends on the kind of the oxide, it is based on the niobium / tantalate alkali based film. It may be 30 wt% or less, for example, 1 to 20 wt%, preferably 1 to 10 wt%, but sometimes 2 wt% or more or 0.01 to 1 wt%.
  • the addition amount of these oxides is preferably an amount known to be dissolved in the niobium / tantalate alkali represented by the above formula. However, even if the addition amount is within the solid solution limit, all may not form a solid solution and may be a mixture.
  • the substrate on which the niobium / tantalate alkali based film is deposited is not limited, but is preferably a substrate having a perovskite crystal structure. If the substrate has a perovskite crystal structure, the crystal structure is the same as that of an alkali of niobium / tantalate, and therefore, it is easy to deposit a niobium / tantalate alkali film, and furthermore, it is possible to form a primary alignment film or an epitaxial film. It is preferable because it can be done.
  • a perovskite type oxide As a substrate having a perovskite crystal structure which is preferably used, a perovskite type oxide can be mentioned, and the perovskite type oxide is ABO 3 (wherein, A is Li, Na, K, Rb, Mg, Ca, It is selected from Sr, Ba, Pb, Bi, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, etc., and B is Mg, Sc, Ti And V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, In, Sn, Hf, Ta, W, Ir, Pb, Bi, etc. A and B are plural. And the oxide is an oxide represented by the solid solution), and examples thereof include BaTiO 3 , PbTiO 3 , KNbO 3 , PbVO 3 and the like.
  • substrates having a perovskite crystal structure Cu 3 Au structure, ReO 3 structure, K 2 NiF 4 structure, Sr 3 Ti 2 O 7 structure and Sr 4 Ti 3 O 10 structure, Bi 4 Ti 3
  • the crystal lattice constant of the substrate used in the present invention is the same as or similar to the crystal lattice constant of the niobium / tantalate alkali based film to be produced, it is preferable because the lattice matching is high.
  • the difference between the crystal lattice constant and the crystal lattice constant of niobium / alkali tantalate is preferably 10% or less, more preferably 5% or less.
  • the crystal lattice constant of alkali niobate is about 0.388 to 0.405 nm, and the crystal lattice constant of alkali tantalate is about 0.395 to 0.405 nm.
  • a substrate having a thickness of about 405 nm or about 0.380 to 0.450 nm, and further about 0.370 to 0.405 nm or about 0.380 to 0.425 nm is preferred. It is preferable that the lattice matching between the substrate and the film is high, because a primary alignment film and further an epitaxial film can be formed. In addition, when the lattice matching between the substrate and the film is high, the film thickness that can be deposited is increased, and there is also an advantage of improving the film forming speed.
  • the substrate used in the present invention preferably exhibits conductivity.
  • the niobium / tantalate alkali based film tends to be deposited.
  • a substrate having a perovskite crystal structure exhibiting conductivity is preferable, and examples thereof include Nb: SrTiO 3 , La: SrTiO 3, and the like.
  • the film thickness of the niobium / tantalate alkali-based film can be remarkably increased, but a substrate (or a buffer having a perovskite crystal structure showing conductivity) By using the layer), the film forming rate can be further improved, so that there is an effect that the thickening of the niobium / tantalate alkali type film can be made more realistic.
  • an alkali niobium / tantalate based system by using a substrate (or buffer layer) having a perovskite crystal structure such as KTaO 3 whose lattice constant or chemical species is close to that of the film.
  • the film thickness of the film can be increased, and the film forming speed can be further improved.
  • a material having a lattice constant or chemical species close to that of the film for example, there is KTaO 3 or the like.
  • the substrate is KTaO 3
  • the film thickness obtained is increased compared to LaAlO 3 , SrTiO 3 or the like having the same perovskite crystal structure. It is possible to preferably combine a substrate (buffer layer) in which the lattice constant or chemical species is close to that of the film and the substrate exhibiting conductivity.
  • the substrate used in the present invention may be a substrate made of other ceramics, metals, plastics or the like in addition to a substrate having a perovskite crystal structure.
  • a buffer layer having a perovskite crystal structure on the surface of the substrate and further having conductivity.
  • SrRuO 3 , BaSrRuO 3 , LaNiO 3 , La 2 NiO 5 , LaSrCoO 3 and the like can be mentioned.
  • Immersion of the substrate in water (or aqueous alkali solution) in the reaction vessel can be carried out using an appropriate holding means as described above. Since the present invention is a hydrothermal synthesis method, the surface of the substrate on which the film is deposited needs to be immersed in water (or an aqueous alkaline solution). The surface of the substrate on which the film is not desired to be deposited may be covered with a protective film or a masking agent.
  • the substrate surface is combined with a region in which the niobium / tantalate is likely to be deposited and a region in which it is difficult to be deposited, selective growth of the niobium / tantalate alkali type film is possible.
  • the hydrothermal synthesis method since the hydrothermal synthesis method is used, it is possible to deposit a niobium / tantalate alkali type film even if the surface of the substrate is not flat and is a curved surface.
  • a uniaxially oriented or epitaxially oriented alkali niobium / tantalate based film can be deposited even if the surface of the substrate is not only a flat surface but also a curved surface.
  • reaction of alkali hydroxide with niobium / tantalum oxide is represented by the following reaction formula: 2AOH + (Nb, Ta) 2 O 5 2 2A (Nb, Ta) O 3 + H 2 O (In the formula, A is an alkali metal and can be one or more kinds.) It is a reaction represented by
  • Nb and Ta are mutually substitutable elements in the hydrothermal synthesis reaction of the present invention, and are considered to act similarly.
  • a (Nb, Ta) O 3 is formed (deposited) on the surface of the substrate, and is also formed as a powder in water (alkali aqueous solution) in the reaction vessel. In practice, most of them are produced as powder in (alkali aqueous solution) and the amount deposited on the substrate surface is limited.
  • the film thickness which can be deposited is remarkably increased as compared with the case of using crystalline niobium / tantalum oxide. It has been found that the deposition efficiency is also improved. This is a breakthrough in thickening of a niobium / tantalate alkali-based alignment film, which is an important issue in the prior art, and is a piezoelectric or pyroelectric including a thick niobium / tantalate alkali-based alignment film. The practical application of the element is made realistic.
  • the film thickness of the film deposited on the substrate in batch processing has been limited to about several ⁇ m, but according to the present invention amorphous niobium / Unexpectedly, the film thickness of the film deposited on the substrate is obviously increased when the tantalum-based oxide is used as a raw material. According to the manufacturing method of the present invention, 10 ⁇ m or more, 12 ⁇ m or more, 15 ⁇ m or more, 17 ⁇ m or more, or even 20 ⁇ m or more is possible.
  • the remarkable improvement of the film thickness that can be formed into a film is a synergistic effect with the improvement of the deposition efficiency, and the practical realization of the piezoelectric or pyroelectric element and the functional device including the niobium / tantalate alkali type film having a large film thickness is further realized.
  • 4 mmol or more, or 0.5 mass% or more of the consumed niobium / tantalum oxide based on 1 mol of consumed niobium / tantalum oxide deposited on the substrate Can be. Furthermore, it may be 10 mmol or more or 1.25 mass% or more. Furthermore, it can be 100 millimole mass% or more or 20 mass% or more.
  • Powdered A (Nb, Ta) O 3 which is not deposited on the substrate, may be reused, for example, by being regenerated to a niobium / tantalum-based oxide.
  • the niobium / tantalate alkali based film deposited on the substrate can be a primary alignment film or an epitaxial film.
  • another crystal film is grown on a certain crystal base, it is observed that one crystal axis of the crystal grows almost in agreement with each other between the crystal film and the crystal base as two crystal axes of the primary alignment film and the crystal. It is called an epitaxial film that the growth is almost in agreement.
  • the heating temperature of the reaction can be, but is not limited to, a low temperature of 300 ° C. or less.
  • the lower limit may be room temperature (about 30 ° C.) or higher, but generally, the range of 50 to 300 ° C., preferably 100 to 250 ° C. is preferable.
  • the reaction temperature can be lower than the Curie temperature of the niobium / tantalate alkali, there is no defect that the film is cracked at the cooling after film formation, and a thicker high quality film can be obtained. You can get it.
  • the film forming temperature is lower than the Curie temperature of the niobium / tantalate alkali
  • the niobium / tantalate alkali-based alignment film exhibiting self-polarization and excellent piezoelectric characteristics without polarization treatment is obtained. be able to.
  • the heating in the reaction vessel may be performed by microwave irradiation as well as by an autoclave. According to the microwave heating, the film forming speed is remarkably improved as compared with the normal heating.
  • an alkali-resistant pressure-resistant reaction container Teflon / PEEK double container
  • a microwave-heatable reactor for example, "flexiWAVE", Milestone General (registered trademark)
  • the water contained in the reaction vessel may be irradiated with microwaves and heated to the set temperature while observing the temperature in the vessel with an optical fiber.
  • the pressure at the time of reaction may be a pressure at which the pressure inside the reaction vessel rises by heating the closed reaction vessel. Usually, it is considered to be about 5.0 ⁇ 10 4 to 3.5 ⁇ 10 6 Pa, but is not limited.
  • the pressure in the closed reaction vessel rises.
  • the niobium / tantalum-based oxide dissolves and a niobium / tantalate alkali-based film is deposited on the surface of the substrate in an inhomogeneous reaction.
  • the reaction time is not limited as long as the raw materials can react. Depending on the production equipment and the composition of the raw material, it may be, for example, about 1 to 72 hours, further about 1.5 to 36 hours, and particularly about 1.5 to 24 hours in one batch process.
  • the reaction time in the production method of the present invention is not necessarily limited to the present invention, but the final film thickness is significantly thicker than in the case of using a conventional crystalline raw material, and the time until the final film thickness is Tend to be longer.
  • the deposition rate in the production method of the present invention may be equal to the deposition rate in the case of using a conventional crystalline niobium / tantalum-based oxide, and the present invention is not limited by the deposition rate.
  • the niobium / tantalate alkali-based film produced by the production method of the present invention has a perovskite-based crystal structure, is uniaxially oriented or epitaxially oriented, and exhibits piezoelectric characteristics.
  • the piezoelectric characteristics of the niobium / tantalate alkali-based film produced according to the present invention are different from those of the film obtained by the hydrothermal synthesis method using the conventional crystalline niobium / tantalum-based oxide. It is confirmed that they are equivalent (refer to the example, FIGS. 14 to 16, etc.).
  • Niobium / tantalate alkaline film formed by the manufacturing method of the present invention has the formula A (Nb 1-x Ta x ) uniaxially oriented niobium / tantalum alkaline represented by O 3 or epitaxial orientation to that oriented film
  • the niobium / alkali tantalate crystals can preferably be single crystals, they may also contain heterophases.
  • the niobium / tantalate alkali-based film obtained by one batch processing has a film thickness of about several ⁇ m when using the conventional crystalline niobium / tantalum-based oxide.
  • the upper limit is used, it is considered that, for example, 10 ⁇ m or more, 12 ⁇ m or more, 15 ⁇ m or more is possible, and further 20 ⁇ m or more is also possible.
  • the film thickness may be in the order of millimeters of 30 to 60 ⁇ m, particularly 60 ⁇ m or more, 70 ⁇ m or more, and further 100 ⁇ m or more, 150 ⁇ m or more, 200 ⁇ m or more, 1 mm or more, or 2 mm or more by batch processing.
  • the upper limit of the film thickness may be determined according to the characteristics of the element or device to be obtained, but may be, for example, 3 mm or less, 1 mm or less, 500 ⁇ m or less, 300 ⁇ m or less, or the like.
  • the piezoelectric or pyroelectric characteristics which can not be realized by the conventional piezoelectric or pyroelectric element can be preferably realized.
  • the niobium / tantalate alkali-based alignment film formed by the manufacturing method of the present invention is excellent in the orientation and can be self-polarized (the polarization direction is uniform even without the polarization treatment). Since it is self-polarizing, it can be used as a piezoelectric element without the poling treatment.
  • the orientation of the niobium / tantalate alkali orientation film can also be improved by selecting the deposition substrate.
  • the obtained niobium / tantalate alkali type film can be post-annealed, and the quality of crystalline film is improved by the post-annealing.
  • the temperature of the post annealing may be, for example, 100 to 900 ° C., 100 to 750 ° C., in particular 500 to 750 ° C.
  • the niobium / tantalate alkali type alignment film which has been post-annealed at high temperature to improve the crystal quality loses self-polarization, and thus may be subjected to polarization processing for use as a piezoelectric or pyroelectric element.
  • a niobium / tantalate alkali-based film containing a uniaxially or epitaxially oriented crystal and a piezoelectric or pyroelectric element or functional device using the same are provided.
  • the niobium / tantalate alkali type film obtained by the present invention is applied to various piezoelectric elements and the like.
  • the base 11 has the lower electrode 12 and the niobium / tantalate alkali type film 13 and the upper electrode 14 thereon.
  • a buffer layer 15 may be provided between the lower electrode 11 and the lower electrode 12 as needed.
  • the niobium / tantalate alkali type film obtained by the manufacturing method of the present invention is widely applied as a piezoelectric film to a piezoelectric actuator element, a pressure sensor, an ultrasonic vibrator, a vibration power generation device and the like.
  • the formula A (Nb 1-x Ta x ) O 3 (wherein A is one or two or more alkali metals, and the ratio of two or more alkali metals is And a niobium / tantalate alkali type film containing crystals uniaxially or epitaxially oriented, wherein the niobium / tantalate alkali type film is 60 ⁇ m or more.
  • a substrate having a thickness of 70 ⁇ m or more (however, 96 mol% or more of A in the formula, particularly 140 ⁇ m or more when 100% is K) and / or including a curved surface
  • An alkali niobium / tantalate based film is provided.
  • the composition A (Nb 1-x Ta x ) O 3 of the niobium / tantalate alkali type film and the components thereof are described in the first aspect. It may be the same as
  • the alkali A may be one or more selected from potassium, sodium, lithium, rubidium, cesium, francium and barium, but it is two types of potassium and sodium or three types of potassium and sodium and lithium. It is preferable to include these. Since the piezoelectric characteristics are improved by the increase in the content of alkali A contained to two or three as compared with potassium or sodium alone, the piezoelectric characteristics can be designed according to the application.
  • y Li / (K + Na + Li) is preferably 0 to 0.1, particularly 0 to 0.05.
  • the niobium / tantalum may be niobium or tantalum alone or may include both niobium and tantalum. Although niobium alone is preferred, it may contain both niobium and tantalum, and 0 ⁇ x ⁇ 0.5, in particular 0.2 ⁇ x ⁇ 0.3. It is preferable that both are included, since the piezoelectric properties are improved by including tantalum together with niobium.
  • the uniaxially oriented or epitaxially oriented film grown on the substrate is separated from the substrate used for growth to form a uniaxially oriented or epitaxially oriented film alone, and another film or substrate is joined to the separated uniaxially oriented or epitaxially oriented film. It may be When the niobium / tantalate alkali type film is a uniaxial alignment film or an epitaxial alignment film, it can have excellent piezoelectric properties.
  • the thickening of 110 ⁇ m or more, preferably 140 ⁇ m or more is not performed.
  • niobium / tantalate alkali-based alignment film is formed on a substrate including a curved surface, a new application (functionality can not be realized with a piezoelectric element using a conventional niobium / tantalate alkali-based alignment film. Device) can be realized.
  • functional devices newly provided by the second aspect of the present invention include, for example, medical ultrasonic probes, ultrasonic transmitters, ultrasonic sensors, pyroelectric generators, vibration generators, and actuators. .
  • the ultrasonic probe is a component that transmits and receives ultrasonic waves, receives ultrasonic waves that are reflected, and displays the images and blood flow information as ultrasonic waves in an ultrasonic inspection apparatus.
  • the niobium / tantalate alkali oriented film of the present invention can transmit and receive ultrasonic waves in a low frequency band of 1 to 100 MHz and further 2 to 100 MHz since the film thickness is larger than that of a conventional niobium / tantalate alkali oriented film. There is a feature.
  • the ultrasonic probe 20 includes a backing material 21, a vibrator (piezoelectric element) 22, an acoustic matching unit 23, and an acoustic lens 24.
  • the backing material 21 is disposed on the back surface of the vibrator, and serves to absorb the propagation of ultrasonic waves to the rear, suppress extra vibration, and shorten the pulse width of the ultrasonic waves.
  • the transducer 22 is a component that transmits and receives ultrasonic waves.
  • the vibrator 22 has a large acoustic impedance as compared with the living body, and the ultrasonic wave is reflected as it is.
  • a material having an acoustic impedance intermediate between the vibrator 22 and the living body is inserted and reflected.
  • Is a member that minimizes the The acoustic lens 24 has a role of focusing the ultrasonic beam, and silicone rubber is often used.
  • the medical ultrasonic probe is a medical ultrasonic diagnostic device that transmits ultrasonic waves to a living body such as a human body and receives reflected ultrasonic waves and displays them as images or blood flow information in medical applications.
  • the part that transmits and receives ultrasonic waves is a probe.
  • the resonance vibration frequency is a low frequency band of 2 to 100 MHz, and the vicinity of the skin (for example, depth 0 to 10 mm) Image diagnosis is made possible.
  • the niobium / tantalate alkali-based alignment film of the present invention has a large film thickness and can generate high-power ultrasonic waves, for example, a machine for inserting an endoscope into a constriction portion in a blood vessel It can be used as a scanning device, and it can also be used as an ultrasonic medical device that uses a high power (amplitude of 1 m / s or higher at a resonance frequency of 2 to 100 MHz) high amplitude ultrasonic waves to break thrombi in blood vessels. .
  • An ultrasonic transmitter is an electroacoustic transducer for transmission that converts an electrical signal into acoustic vibration and emits a sound wave to a medium. In many cases, it is also used as a transducer for receiving waves, and also has the function of converting acoustic vibration into an electrical signal.
  • the ultrasonic sensor emits ultrasonic waves and then receives ultrasonic waves reflected back from the object, detects an object, measures the time of returning wrinkles, and measures the distance to the object
  • the sensor that does this is an ultrasonic sensor.
  • a signal voltage is applied to a vibrator (piezoelectric element), and an ultrasonic wave at a resonant vibration frequency of the vibrator is radiated from the speaker (transmitter) into the air.
  • the wave of the ultrasonic wave from the air is received by the microphone (receiver), and the transducer generates an electric output.
  • a transmitter and a receiver are collectively called an ultrasonic transducer (electro-acoustic transducer).
  • the niobium / tantalate alkali-based alignment film of the present invention has a high output (1 to 3 m as a vibration velocity in a frequency band of several tens of kHz) as compared to a niobium / tantalate alkali-based alignment film manufactured by a conventional hydrothermal synthesis method.
  • Such an ultrasonic sensor has high output and can be advantageously used for obstacle detection and distance measurement in a car.
  • the pyroelectric element 31 is formed by sandwiching the ferroelectric substance 32 between the electrodes 33.
  • the heat source 34 that changes with time acts on the pyroelectric element 31
  • a voltage that fluctuates in the ferroelectric 32 is generated according to the temperature change, and power generation is performed.
  • the niobium / tantalate based alkali oriented film of the present invention has higher piezoelectric properties as compared to the niobium / tantalate based alkali oriented film produced by the conventional hydrothermal synthesis method, a lead-free piezoelectric element is used. It is promising as a pyroelectric generator.
  • a vibration power generation device is a power generation device which converts vibration of a vibrator into electric power and takes it out by applying mechanical external force and vibration to the vibrator (piezoelectric element).
  • the niobium / tantalate alkali-based alignment film of the present invention has a high output (1.7 ⁇ W ⁇ G ⁇ at a resonance frequency of 200 Hz or less), as compared to a niobium / tantalate alkali-based alignment film manufactured by a conventional hydrothermal synthesis method. Since the output power density of 2 mm- 3 ) and the output close to that of PZT, it is promising as a vibration power generator using a lead-free piezoelectric element.
  • the actuator is a device that displaces the piezoelectric body itself by applying a voltage to the piezoelectric element (inverse piezoelectric effect) to generate a mechanical force. Since the niobium / tantalate based alkali oriented film of the present invention has higher piezoelectric properties as compared to the niobium / tantalate based alkali oriented film produced by the conventional hydrothermal synthesis method, a lead-free piezoelectric element is used. It is promising as an actuator.
  • Amorphous niobium oxide (a-Nb 2 O 5 ) was prepared by the following procedure. A mixture of niobium oxide Nb 2 O 5 (reagent obtained from Kanto Chemical Co., crystalline substance: 10 g) and potassium carbonate K 2 CO 3 (52 g) in a platinum crucible is heated at 950 ° C. for 1 hour for melting. The white cake obtained by allowing to cool was dissolved in distilled water (500 mL).
  • FIG. 5 shows X-ray diffraction charts of the obtained amorphous niobium oxide and crystalline niobium oxide.
  • a (K, Na) NbO 3 film (KNN film) was produced by a hydrothermal synthesis method as follows.
  • the sealed autoclave is heated to 240 ° C. for 6 hours to carry out a hydrothermal synthesis reaction, and then the taken out substrate is washed with deionized water several times and dried at 150 ° C. to give a film thickness of about 11 ⁇ m (K, Na ) NbO 3 (KNN film) was obtained.
  • An X-ray diffraction chart of the KNN film is shown in FIG. 6, and it is confirmed that a (K, Na) NbO 3 film having a perovskite structure is obtained and it is an epitaxial film.
  • FIG. 6 when the film thickness of the KNN film having a short reaction time is 2 ⁇ m (FIG. 6 (c) and (d)), and when the film thickness is almost maximum 10 ⁇ m (FIG. 6 (a) and (b) 1 shows an X-ray diffraction chart of.
  • the film thickness of about 11 ⁇ m of the KNN film is the maximum film thickness when the reaction time is changed under the conditions of Example 1.
  • the relationship between the reaction time and the obtained film thickness is shown by a graph in FIG. 7 (a).
  • the film thickness increases with an increase in reaction time up to about 6 hours, but when the maximum film thickness of about 11 ⁇ m is reached thereafter, the film thickness does not increase even if the reaction time increases.
  • FIGS. 8 (c) and (d) and FIGS. 9 (c) and (d) show SEM photographs of a plane and a longitudinal cross section of the obtained KNN film.
  • the plan views of FIGS. 8 (c) and 8 (d) are plan photographs when the film thickness is different between 2 ⁇ m and 10 ⁇ m, but it is recognized that the crystal grain size increases as the film thickness increases.
  • amorphous niobium oxide (non-hydrate; a-Nb 2 O obtained by calcining at 200 ° C. the amorphous niobium oxide (hydrate) produced by the above method to remove hydration water. 5 ) After confirming that it was non-hydrated by X-ray diffraction, a KNN film was prepared in the same procedure as above, but the results are the same as in the case of the hydrate, and the difference in the results is I was not able to admit. In the following examples, amorphous niobium oxide (hydrate) was used, but is simply described as amorphous niobium oxide.
  • Example 2 6 mol / L
  • the KNN film of Example 2 was produced in the same manner as in Example 1, except that the concentration of potassium hydroxide and sodium hydroxide in the hydrothermal synthesis of the KNN film was changed from 7 mol / L to 6 mol / L.
  • the reaction time for obtaining the maximum film thickness was 16 hours.
  • FIG. 7A also shows the relationship between the reaction time and the film thickness of the KNN film obtained in Example 2 as a graph.
  • the deposition rate of the film thickness of the KNN film of Example 2 was slower than that of Example 1, but the maximum film thickness reached about 17 ⁇ m at a reaction time of about 16 hours, and did not increase further.
  • the film forming time is 3 times longer and the film thickness is 3 times or more in the case of the amorphous material as compared with the case of the crystalline material. ing.
  • the amount of the niobium raw material for obtaining the same film thickness is 1/3 or less than that of crystalline in amorphous.
  • Example 3 Amount of raw material, precipitation efficiency
  • the amorphous niobium source was reduced from 0.25 g to 0.10 g and 0.05 g to deposit the KNN film as well.
  • the film thickness of each of the obtained KNN films was about 17 ⁇ m. Therefore, the use of an amorphous material can increase the use efficiency of the niobium material as compared to a crystalline material.
  • the deposition efficiency of the KNN film is calculated in the film forming to the dimension of 15 ⁇ 15 mm of the substrate under the same conditions, and when the raw materials are 0.25 g of crystalline material, 0.25 g of amorphous material and 0.05 g of amorphous material, 1.38% and 4.04%, respectively. It was 20.2%. The deposition efficiency can be improved about 22 times with respect to the crystalline raw material.
  • the reaction time was the time until the maximum film thickness was confirmed.
  • KNN films were all (K, Na) NbO 3 films having a perovskite structure, as in Example 1.
  • FIG. 11 is a graph showing the maximum film thicknesses of the KNN films obtained in Example 1 and Examples 4 to 7, corresponding to the ratio of [KOH] / ([KOH] + [NaOH]) in the raw materials.
  • the corresponding result of the below-mentioned comparative example when crystalline niobium oxide is used as the raw material is also shown in FIG. 11, all [KOH] / ([KOH] / ([KOH]) are compared in the example as compared with the corresponding comparative example. It can be observed that the maximum film thickness is increased at the ratio of [+ NaOH].
  • the [KOH] / ([KOH] + [NaOH]) ratio is about 0.7 to 1.0, in particular 0.75 to 1.0, the maximum film thickness is also compared to the increase in film thickness relative to the conventional example. It is big.
  • Example 8 deposited seven times
  • the obtained KNN film was 0.13 mm.
  • the film thickness of the obtained KNN film was less than 50 ⁇ m.
  • FIG. (A) is an amorphous niobium raw material
  • (b) is a KNN film obtained from a crystalline niobium raw material.
  • the obtained KNN film was a (K, Na) NbO 3 film having a perovskite structure similar to that of the KNN films of Examples 1 and 2.
  • the maximum film thickness of the obtained KNN film was about 5.5 ⁇ m in both Comparative Examples 1 and 2, and there was almost no difference.
  • FIGS. 13 (a) and (b) show the charts of FIGS. 7 (a) and 7 (b) under the same conditions as in Example 1 and Comparative Example 1 except that the raw material is crystalline or amorphous. Comparison (FIG. 13 (a)) and comparison between Example 2 and Comparative Example 2 (FIG. 13 (b)) are shown. It can be seen from FIGS. 13 (a) and 13 (b) that the maximum film thickness is significantly increased by changing the raw material from crystalline to amorphous under the same synthesis conditions.
  • the obtained KNN films were all (K, Na) NbO 3 films having a perovskite structure, as in Comparative Example 1.
  • a graph corresponding to the ratio of ⁇ K / (K + Na) in the KNN film of FIG. 10 to the ratio of [KOH] / ([KOH] + [NaOH]) in the raw material, and the maximum in the KNN film of FIG.
  • the graphs corresponding to the film thickness and the ratio of [KOH] / ([KOH] + [NaOH]) in the raw materials correspond to those of Examples 1, 2 and 4 to 7, and the results of Comparative Examples 1 to 2 are also shown. Show.
  • the maximum film thickness is increased by changing the raw material from crystalline to amorphous as compared with the comparative example in all the raw material compositions.
  • Example 9 and Comparative Example 7 Preparation of Piezoelectric Element, Piezoelectric Property
  • a KNN film obtained by depositing a KNN film having a perovskite structure on an SrTiO 3 substrate on which SrRuO 3 is formed and annealing at 600 ° C. for 10 minutes using a tubular furnace Platinum electrodes were deposited thereon by sputtering, and the piezoelectric elements of Example 9 and Comparative Example 7 were produced, in which the KNN film was sandwiched between the upper and lower electrodes.
  • the film thicknesses of the KNN films in the piezoelectric elements of Example 9 and Comparative Example 7 were 2.0 ⁇ m and 2.4 ⁇ m, respectively, so as to make the film thickness of the comparison object equal.
  • Example 10 Correlation between K / Na ratio and piezoelectric (power generation) characteristics
  • Example 10 Correlation between K / Na ratio and piezoelectric (power generation) characteristics
  • a KNN film having a perovskite structure was deposited on an SrTiO 3 substrate on which SrRuO 3 was formed by changing the ratio of potassium hydroxide and sodium hydroxide.
  • the power generation characteristics of the obtained KNN film after deposition (as depo.) And the film after heat treatment at 600 ° C. are shown in FIG.
  • Example 11 and Comparative Example 8 Piezoelectric Properties Piezoelectric elements of Example 11 and Comparative Example 8 were produced in the same manner as in Example 9 and Comparative Example 7. However, the film thicknesses of the KNN films in the piezoelectric elements of Example 11 and Comparative Example 8 were 10 ⁇ m and 5 ⁇ m, respectively.
  • Example 11 and Comparative Example 8 The voltage polarization hysteresis curve and the electric field induced strain were measured for each piezoelectric element of Example 11 and Comparative Example 8 in the same manner as in Example 9 and Comparative Example 7, and the results are shown in FIGS. 18 (a) to (e) and FIG. 19 (a) to (e). Even when the film thickness changes (increases), it is shown that the piezoelectric characteristics of the piezoelectric element of the example are equivalent to the piezoelectric characteristics of the comparative example.
  • Example 12 annealing temperature
  • Example 12 annealing temperature
  • the KNN film in the piezoelectric element of Example 12 was one that was not annealed after hydrothermal synthesis, and the annealing temperatures were 500 ° C., 600 ° C., 700 ° C., and 750 ° C., respectively.
  • the results of measuring the piezoelectric characteristics of these piezoelectric elements are shown in FIG.
  • Example 13 Thickness Before and After Annealing Treatment
  • SrRuO 3 SrRuO 3 // SrTiO 3
  • the KNN membrane was obtained.
  • the thickness of this KNN film was measured before and after the annealing treatment, and was about 8 to 10 ⁇ m in the non-annealing treatment, but a film thickness of about 12 ⁇ m was obtained after the annealing treatment.
  • Example 14 Low temperature film forming KNN film
  • a KNN film was obtained by changing the film formation temperature of 240 ° C. to 200 ° C. and 150 ° C., respectively.
  • an epitaxial KNN film of the perovskite structure was confirmed as in the case of 240 ° C.
  • the KNN film could be formed using an amorphous raw material at a low temperature of 150 ° C.
  • FIG. 21 shows the film thickness of the KNN film obtained at the above temperature, in contrast to the case where crystalline niobium oxide is used as a raw material. When an amorphous material is used, the film thickness of the KNN film is larger than that of a crystalline material at any film forming temperature.
  • Example 15 and Comparative Example 9 7 mol / L Piezoelectric Properties
  • a piezoelectric element of Example 15 was produced in the same manner as Example 9. However, the KNN film was produced by the same method as in Example 2 and Comparative Example 2.
  • the piezoelectric characteristics of the piezoelectric element having the same film thickness of the KNN film in Example 15 and Comparative Example 9 were evaluated by the method described in Example 9, but no substantial difference in the characteristics was observed between the two.
  • Example 16 and Comparative Example 10 KNT Film
  • a (K, Na) TaO 3 (KNT film) of Example 16 was produced in the same manner as Example 1, except that tantalum oxide was used instead of niobium oxide. That is, the preparation of the amorphous Ta 2 O 5 and the preparation of the KNT film using the amorphous Ta 2 O 5 were the same as in Example 1.
  • Amorphous tantalum oxide (a-Ta 2 O 5 ) was prepared by the following procedure.
  • a mixture of tantalum oxide Ta 2 O 5 (reagent obtained from Kanto Chemical Co., crystalline substance: 10 g) and potassium carbonate K 2 CO 3 (156 g) in a platinum crucible is heated at 950 ° C. for 1 hour for melting.
  • the white cake obtained by allowing to cool was dissolved in distilled water (500 mL).
  • the solution was filtered to remove solids, and then an acidic aqueous solution of nitric acid HNO 3 (200 mL) dissolved in deionized water H 2 O (200 mL) was added to precipitate a white powder.
  • the precipitate was filtered off, washed with deionized water and dried at 50 ° C. It was amorphous tantalum oxide which was obtained and was hydrated (a-Ta 2 O 5 ⁇ n H 2 O). The obtained amorphous tantalum oxide (hydrate) is calcined at 200 ° C. to remove water of hydration, thereby obtaining amorphous tantalum oxide (non-hydrate; a-Ta 2 O 5 ). The It was confirmed by X-ray diffraction that it was non-hydrate. 22 (c) and (d) show X-ray diffraction charts and SEM photographs of the obtained amorphous tantalum oxide, and FIGS. 22 (a) and (b) show X-rays of the corresponding crystalline tantalum oxide. The diffraction chart and the SEM photograph are shown.
  • Example 16 using the prepared amorphous tantalum oxide, the same procedure as in Example 1 is carried out in the same procedure as in Example 1 (alkali solution concentration 7 mol /, using 0.416 g as the number of moles of amorphous niobium oxide 0.25 g in Example 1).
  • L, K: Na 9: 1, hydrothermal condition: 240 ° C., 6 h), (K, Na) TaO 3 film (KNT film) of Example 16 was produced.
  • the ⁇ K / (K + Na) ratio of the KNT film of this Example 16 was 0.480, and the maximum film thickness of the KNT film was about 600 nm.
  • a (K, Na) TaO 3 film (KNT film) of Comparative Example 10 was produced in the same manner as described above except that commercially available crystalline tantalum oxide was used instead of amorphous tantalum oxide.
  • the ⁇ K / (K + Na) ratio of the KNT film of Comparative Example 10 was 0.570, and the maximum film thickness of the KNT film was about 100 nm.
  • Example 17 KTaO 3 substrate
  • the KNN film was formed in the same manner as in Example 1 except that LaAlO 3 , SrTiO 3 , and KTaO 3 were used as the substrate, and the preparation amount of the raw material a-Nb 2 O 5 was 0.25 g.
  • the substrate was LaAlO 3 or SrTiO 3
  • the KNN film could be formed at last, but when the substrate was KTaO 3 , a KNN film having a thickness of about 7 ⁇ m close to that of Example 1 could be formed.
  • film thickness by about 4 times the good epitaxial film of the KNN layer when the raw material charged amounts from 0.25g to 1 g (4-fold) was obtained.
  • Example 18 and Comparative Example 11 Inconel Substrate
  • Example 1 and Example 1 using a metal substrate having a buffer layer (SrRuO 3 / LaNiO 3 ) on which a 50 nm LaNiO 3 film and a 50 nm SrRuO 3 film are deposited by sputtering on the surface of a commercially available Inconel (registered trademark) metal substrate.
  • a buffer layer SrRuO 3 / LaNiO 3
  • a 50 nm LaNiO 3 film and a 50 nm SrRuO 3 film are deposited by sputtering on the surface of a commercially available Inconel (registered trademark) metal substrate.
  • KNN films of Example 18 and Comparative Example 11 were produced.
  • Example 18 and Comparative Example 11 had film thicknesses of 8.5 ⁇ m and 4.6 ⁇ m, respectively.
  • An X-ray diffraction chart of the KNN films obtained in Example 18 and Comparative Example 11 is shown in FIG. In Example 18, the film thickness is clearly increased as compared with Comparative Example 11, but the crystallinity is the same as in Comparative Example 11.
  • the KNN film is a single phase with a nearly perfect ⁇ 100 ⁇ orientation although a very slight ⁇ 110 ⁇ peak is observed. It is based on ⁇ 100 ⁇ self-orientation of LaNiO 3 film.
  • the deposition of the above-mentioned KNN film was repeated four times to produce a KNN film having a film thickness of about 30 ⁇ m.
  • the orientation of this film was evaluated by the half width (FWHM), it was confirmed that the half width (FWHM) decreased from 23 ° to 14 ° as the thickness increased, and the degree of orientation was improved ( Degree of orientation 99.5%).
  • FIG. 23 (b) shows X-ray diffraction charts of the KNN films obtained in Example 1 and Comparative Example 1.
  • the crystallinity of the KNN films prepared on the metal substrates obtained in Example 18 and Comparative Example 11 is the same as the KNN film on the SrRuO 3 // SrTiO 3 substrate obtained in Example 1 and Comparative Example 1 (The difference between the peaks in FIG. 23 (a) and FIG. 23 (b) is based on the difference in the substrate).
  • the piezoelectric constant was improved by the Ta substitution.
  • Example 19 ⁇ 111 ⁇ orientation on Pt substrate
  • the KNN film of Example 19 was produced.
  • the X-ray diffraction result of the obtained KNN film is shown in FIG. It is observed that the KNN film is ⁇ 111 ⁇ oriented. It is a result that the Pt film has ⁇ 111 ⁇ self-orientation, but it has been separately confirmed that the Pt film and SrRuO 3 are ⁇ 111 ⁇ oriented.
  • Example 20 KNNT membrane
  • KOH: NaOH 9: 1, Nb constant
  • Nb Nb constant
  • the (K, Na) (Nb, Ta) O 3 film (hereinafter also referred to as a KNNT film) was manufactured by continuously changing the composition ratio of / Ta to 0 to 1.0.
  • the obtained KNNT film is an epitaxial oriented crystal film.
  • the Nb / (Nb + Ta) ratio and the K / (K + Na) ratio of the film are shown in Figure 25.
  • the Nb / (Nb + Ta) ratio varies continuously from 0.68 to 1.0, K / (K +)
  • the Na) ratio changes continuously from 0.83 to 0.92.
  • Example 21 KNLN film
  • (100) La: SrTiO 3 as a substrate, (a-Nb 2 O 5 ) as a powder raw material, and potassium hydroxide, sodium hydroxide and lithium hydroxide as an alkali, 240 A (K, Na, Li) NbO 3 film (hereinafter also referred to as a KNLN film) was produced at ° C., and it was confirmed that an epitaxially oriented crystal film was obtained.
  • the obtained KNLN film was analyzed by X-ray diffraction analysis while changing continuously, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10.
  • the KNLN film is an epitaxial film at all compositions, but when A is 0.05 or more, heterophase peaks consisting of K, Na, Li, Nb, and O were observed.
  • Example 22 KNLNT membrane
  • potassium hydroxide as alkali, sodium hydroxide and lithium hydroxide
  • feed composition ratio [KOH] / ([KOH] + [NaOH]) K, Na, Li) (Nb, Ta) O 3 film
  • Also referred to as KNLNT film Also referred to as KNLNT film
  • the piezoelectric characteristic d 33 was 121 pm / V.
  • Example 23 self polarization
  • the KNN film of Example 23 was formed in the same manner as in Example 1.
  • a piezoelectric element (film thickness 10 ⁇ m) was produced in the same manner as in Example 11 using the obtained KNN film, and the piezoelectric characteristics were evaluated.
  • As the piezoelectric characteristics measurement of the PE hysteresis curve, and the piezoelectric constant e31 , f with respect to the polarization processing electric field were evaluated. In the latter case, a pulse voltage at a measurement frequency of 1 kHz and a measurement voltage of 5 Vp-p was applied as polarization treatment to measure e 31, f .
  • FIG. 27 shows a PE hysteresis curve measured for a piezoelectric element manufactured using a KNN film of as depo. And a KNN film heat-treated at 600 ° C. and e 31, f with respect to a polarization-treated electric field.
  • the KNN film of as depo. Has a large PE hysteresis curve shifted to the negative electric field side (upper drawing in FIG.
  • FIG. 28 shows ferroelectric characteristics e 31, f measured on a piezoelectric element manufactured using the KNN film of as depo. And the KNN film heat-treated at 600 ° C.
  • A is a 2.8 ⁇ m thick as depo.
  • B is a 2.5 ⁇ m thick 600 ° C. heat-treated KNN film,
  • (c) is a comparison of the characteristics of (a) and (b),
  • (d) Is the value of the ferroelectric property.
  • FIG. 30 shows AFM (d 33 ) measured for a piezoelectric element manufactured using the KNN film as as depo. And the KNN film heat-treated at 600 ° C. The heat treatment (annealing) improves the piezoelectric characteristics of the KNN film.
  • the open squares ( ⁇ ) are the values of AFM (d 33 ) reported in the literature for (K 0.5 Na 0.5 ) NbO 3 , and the KNN film obtained in Example 23 is as in the case of as depo.
  • the KNN film also has a value comparable to the previously reported value, and the heat treatment is superior to the previously reported value.
  • the KNN film heat-treated at 600 ° C. has no shift in the PE hysteresis curve (FIG. 27 lower left) and from e 31, f depending on polarization voltage (FIG. 27 lower). Right), it is confirmed that there is no self-polarization and that the piezoelectric characteristics require polarization treatment.
  • the upper graph in FIG. 31 shows the change in shift amount of the PE hysteresis curve when the heat treatment temperature is changed. As the heat treatment temperature increases from the as depo. KNN film, the shift amount decreases.
  • the lower graph in FIG. 31 shows the relationship between the amount of water in the film calculated from the above-mentioned OH release amount and the shift amount of the PE hysteresis curve. It can be seen that the shift amount of the PE hysteresis curve is correlated with the amount of water in the membrane.
  • Example 24 water / alcohol mixed solvent
  • the absorption intensity pattern when infrared absorption analysis (FTIR) is performed is shown in FIG. It shows in FIG. 32 (a) including the case of 240 degreeC.
  • the absorption intensity is an arbitrary unit, and only the absorption pattern has meaning.
  • the KNN film deposited at 180 ° C. OH - hints lot, OH - KNN film amount was deposited at 200 ° C. of, it has become less in the order of KNN film deposited at 240 ° C. I understand.
  • Example 2 In the same manner as in Example 1, that is, the heating temperature is 240 ° C., but the water solvent in the autoclave is replaced with a water / alcohol mixed solvent (mixing weight ratio 8.0 / 1.6) to deposit a KNN film. did.
  • the water content of the KNN powder produced in the water solvent in Example 1 and the KNN films obtained in Example 1 and Example 24 was evaluated by heating the sample and degassing mass spectrum (TDS). The results are shown in FIG. 32 (b). According to FIG. 32 (b), the water content at the peak (near 400 to 500 ° C.) from which OH incorporated in the crystal is released is 2.8 times smaller than that of the KNN powder in the KNN film.
  • the KNN film obtained with the water / alcohol mixed solvent is reduced to one fifth or less compared to the KNN film obtained with the water solvent. Therefore, it is confirmed that the water content in the KNN film is greatly reduced and the water content in the KNN film can be controlled by changing the composition of the solvent by using the water / alcohol mixed solvent.
  • Example 25 Fatigue Property
  • one end of a piezoelectric element manufactured by holding both surfaces of a KNN film heat-treated as depo., 300 ° C. and 600 ° C. with an electrode is fixed to form a cantilever, and a voltage of 10 V is applied to the piezoelectric element.
  • An alternating voltage with a frequency of 1 kHz was applied to repeatedly drive the cantilever (piezoelectric element) to evaluate fatigue characteristics. In any case, no change was observed in the piezoelectricity even after 10,000,000 cycles.
  • the piezoelectric element of the KNN film heat-treated at 300 ° C. and 600 ° C. was heat-treated at 250 ° C., but no characteristic deterioration and no depolarization were observed.
  • Example 26 Polysulfone foil substrate
  • a substrate LaNiO 3 / Pt / Ti / polysulfone
  • a LaNiO 3 film 100 nm thick
  • a flexible polysulfone foil 500 ⁇ m thick
  • a 10 ⁇ m thick KNbO 3 film was formed at a film forming temperature of 150 ° C. to obtain a KNbO 3 film having a single phase of perovskite structure.
  • a substrate on which a LaNiO 3 film (100 nm thickness) was deposited (LaNiO 3 / Pt / Ti / polysulfone)
  • a KNbO 3 film was formed to a thickness of 10 ⁇ m in the same manner as described above, and a Pt electrode was deposited thereon as a top electrode to fabricate a piezoelectric element model.
  • the obtained piezoelectric element model was able to be bent to a radius of curvature of 10 mm, and there was no macro peeling or crack in the KNbO 3 film.
  • piezoelectric element model an electric field-electric field induced strain (SE) curve caused by the piezoelectric property was observed, and the piezoelectric property was confirmed on the organic substrate, which confirmed that the element was a piezoelectric element.
  • FIG. 33 shows the observed change in power generation characteristics and the change in output power (dotted line) calculated from the basic characteristics of the piezoelectric element, and it was found that they coincide very well. In addition, the maximum output power was about 3.6 ⁇ W.
  • the output power density of the power generation element is 1.7 ⁇ W / G 2 / mm 3 , compared to the output power density (0.5 ⁇ W / G 2 / mm 3 or less) in the frequency band of 200 Hz or less conventionally reported for KNN films. Too big.
  • Example 27 U-shaped, wound substrate
  • a KNN film was produced in the same manner as in Example 1 using a substrate prepared by bending this metal foil into a U shape having a curvature radius of about 5.3 mm and embedding the end of the metal foil in a Teflon groove. The film thickness was about 14 ⁇ m.
  • Example 1 using the same metal foil (SrRuO 3 // metal foil) as described above, using a substrate bent to the shape of a spiral spring (two turns and a half turns) having a maximum diameter of about 0.8 cm, Example 1 and A KNN film was produced in the same manner.
  • the film thickness was about 12 ⁇ m.
  • the KNN film is an orientation film of a perovskite structure in which crystals with ⁇ 100 ⁇ and ⁇ 110 ⁇ orientation are mixed, but uniaxially oriented, and the SrRuO 3 film is ⁇ 100 ⁇ orientation.
  • the piezoelectric characteristics of the KNN films formed on these curved substrates are good as in the case where the substrate is flat, in any of the residual polarization and coercive electric field in the PE hysteresis curve, the IV characteristics and the leakage current. showed that.
  • Example 28 Microwave heating
  • the inside of the autoclave was heated to 240 ° C. by an electric heating element, but in Example 28, as shown in FIGS. 34 (a) to (c), the autoclave was replaced with microwave heating, Of the aqueous solution 42 contained in an alkali-resistant, pressure-resistant reaction vessel (Teflon / PEEK double vessel) 41 arranged in a possible reactor ("flexiWAVE", Milestone General®) 40 Then, while observing the temperature inside the container with an optical fiber, heat to a set temperature of 220 ° C., under the same conditions as Example 1. The film was formed on the substrate 43.
  • Teflon / PEEK double vessel arranged in a possible reactor
  • composition, crystallinity, orientation, and piezoelectric properties of the KNN film obtained by microwave heating were similar to those of the KNN film obtained by normal heating.
  • the film forming time can be significantly shortened compared to the case of normal heating, and for example, a KNN film having a film thickness requiring several hours can be formed in a short time of 1 hour or less.
  • Reaction vessel 2 Water (alkaline aqueous solution) 3: Niobium / tantalum-based oxide 4: Substrate 5: Mounting tool 10: Piezoelectric element 11: Substrate 12: Lower electrode 13: Niobium / alkali tantalate film 14: Upper electrode 15: Buffer layer 20: Ultrasonic probe 21: Backing material 22: vibrator (piezoelectric element) 23: Acoustic matching unit 24: Acoustic lens 30: Pyroelectric generator 31: Pyroelectric element 32: Ferroelectric 33: Electrode 34: Heat source

Abstract

The present invention provides a highly productive method for producing alkali niobate/tantalate alignment films, the method using hydrothermal synthesis and enabling the production of thicker films. The present invention also provides a piezoelectric body that uses this alignment film; and a functional device. A substrate is immersed in a water-containing solvent containing an alkali hydroxide and an amorphous niobium/tantalum oxide in a reactor, and heat and pressure is applied thereto, to deposit an alkali niobate/tantalate film having a perovskite-type crystal structure on the substrate. The niobium/tantalum oxide is a simple substance, solid solution, or mixture of niobium oxide and tantalum oxide, as represented by the average compositional formula (Nb1-xTax)2O5 (in the formula, 0 ≤ x ≤ 1), wherein these may be hydrates. The alkali niobate/tantalate film is a crystal containing alkali niobate/tantalate represented by the formula A(Nb1-xTax)O3 (in the formula, A is one or two or more alkali metals wherein any proportions may be used for the two or more alkali metals, and 0 ≤ x ≤ 1).

Description

圧電体膜の製造方法Method of manufacturing piezoelectric film
　本発明は、圧電体膜の製造方法、とりわけニオブ／タンタル酸アルカリ系の圧電体膜の水熱合成法による製造方法に関する。 The present invention relates to a method for producing a piezoelectric film, and more particularly to a method for producing a niobium / tantalate piezoelectric film by a hydrothermal synthesis method.
　圧電体はアクチュエータ素子、圧力センサ、超音波振動子などに広く利用されるほか、最近では振動発電デバイスへの応用にも注目が集まっている。現在使用されている圧電体としてはチタン酸ジルコン酸鉛（ＰＺＴ）系が主流であるが、環境負荷の観点から非鉛系の圧電体が模索されており、様々の非鉛系圧電体のうち、ペロブスカイト構造を有するニオブ／タンタル酸アルカリ系圧電体は、優れた圧電特性、機械結合性及び高いキュリー温度を有していることから、上記応用の有力な候補である。 Piezoelectric materials are widely used for actuator elements, pressure sensors, ultrasonic transducers and the like, and recently, application to vibration power generation devices has also attracted attention. Although lead zirconate titanate (PZT) is the mainstream as the piezoelectric material currently used, lead-free piezoelectric materials are being sought from the viewpoint of environmental load, and among various lead-free piezoelectric materials An alkali niobium / tantalate piezoelectric material having a perovskite structure is a strong candidate for the above application because it has excellent piezoelectric properties, mechanical bondability and high Curie temperature.
　また、従来の圧電体膜は、主に化学気相堆積法、スパッタリング法などの気相プロセスや、ゾルゲル法などの液相プロセスによって製膜されているが、いずれも５００℃以上１０００℃近くまでの高温製膜あるいはプロセス温度（ゾルゲル法では非結晶相を結晶化するプロセス）が必要である。そのため、ニオブ／タンタル酸アルカリ系圧電体では、蒸気圧の高いＫやＮａが揮発するなどのため、組成ずれを生じるという問題がある。これに対して、水熱合成法を用いるとニオブ／タンタル酸アルカリ系圧電体を３００℃以下の低いプロセス温度で製膜でき、ＫやＮａの蒸発はほとんど起きず、定比組成の膜を安定して得られる利点がある（特許文献１、非特許文献１）。 In addition, conventional piezoelectric films are mainly formed by vapor phase processes such as chemical vapor deposition and sputtering, and liquid phase processes such as sol-gel method, but all of them are from 500 ° C. to nearly 1000 ° C. High temperature film formation or process temperature (in sol-gel method, a process of crystallizing non-crystalline phase) is required. Therefore, in the niobium / tantalate alkali type piezoelectric material, there is a problem that composition deviation occurs because K and Na having high vapor pressure volatilize. On the other hand, when using the hydrothermal synthesis method, it is possible to form a niobium / tantalate alkali type piezoelectric material at a low process temperature of 300 ° C. or less, almost no evaporation of K or Na occurs, and a film having a constant ratio composition is stabilized. There is an advantage that can be obtained (Patent Document 1, Non-Patent Document 1).
特開2012-106902号公報JP 2012-106902 A
　従来の水熱合成法によるニオブ／タンタル酸アルカリ系圧電体膜は、密閉容器（オートクレーブ）内で作製されるが、一回のバッチ処理で製膜できる膜厚は数μｍ程度が限界であり、生産性が劣るので、圧電体膜の厚膜化に問題があった。また、従来の水熱合成法による圧電膜は配向性が低いという問題もあった。 Conventional niobium / alkali tantalate piezoelectric films are manufactured in a closed vessel (autoclave), but the film thickness that can be formed in a single batch process is limited to about several μm, Since the productivity is inferior, there is a problem in increasing the thickness of the piezoelectric film. In addition, there is also a problem that the piezoelectric film by the conventional hydrothermal synthesis method has low orientation.
　そこで、本発明は、上記の利点を有する低温製膜できる水熱合成法を用いる方法において、ニオブ／タンタル酸アルカリ系圧電体膜の厚膜化を可能にするニオブ／タンタル酸アルカリ系圧電体膜の製造方法を提供すること、並びに厚膜のニオブ／タンタル酸アルカリ系圧電又は焦電体膜及びそれを利用した圧電又は焦電素子及び機能性装置を提供することを目的とする。 Therefore, the present invention is a method of using a hydrothermal synthesis method capable of low-temperature film formation having the above-mentioned advantages, wherein the niobium / tantalate alkali type piezoelectric film enables thickening of the niobium / tantalate type piezoelectric film. It is an object of the present invention to provide a method of manufacturing the above, and to provide a thick film niobium / tantalate alkali based piezoelectric or pyroelectric film and a piezoelectric or pyroelectric element and a functional device using the same.
　本発明は、上記目的を達成するために鋭意努力した結果、反応容器内において、水酸化アルカリと、非晶質ニオブ／タンタル系酸化物とを含む水含有溶媒中に、基体を浸漬し、加熱及び加圧して、基体上にペロブスカイト系の結晶構造を有するニオブ／タンタル酸アルカリ系膜を堆積することで、上記目的を達成できることを見出して、完成されたものである。以下に本発明の好ましい態様の例を限定の意図なく記載する。これらの態様を任意に組み合わせることができることは明らかである。特に、請求の範囲に記載した態様の組合せは好ましい。 As a result of earnest efforts to achieve the above object, the present invention immerses and heats a substrate in a water-containing solvent containing alkali hydroxide and amorphous niobium / tantalum oxide in a reaction vessel. Then, under pressure, a niobium / tantalate alkali-based film having a perovskite crystal structure is deposited on a substrate to complete the above-described object. In the following, examples of preferred embodiments of the present invention will be described without intention of limitation. It is obvious that these aspects can be combined arbitrarily. In particular, a combination of the embodiments described in the claims is preferred.
　本発明の第一の側面によれば、反応容器内において、水酸化アルカリと、非晶質ニオブ／タンタル系酸化物とを含む水含有溶媒中に、基体を浸漬し、加熱及び加圧して、前記基体上にペロブスカイト系の結晶構造を有するニオブ／タンタル酸アルカリ系膜を堆積すること、前記ニオブ／タンタル系酸化物は、平均組成式（Ｎｂ１－ｘＴａｘ）２Ｏ５（式中、０≦ｘ≦１である。）で表される酸化ニオブ、酸化タンタルの単体、固溶体またはそれらの混合物であり、それらは水和物でもよく、前記ニオブ／タンタル酸アルカリ系膜は、式Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３（式中、Ａはアルカリ金属の１種または２種以上であり、２種以上のアルカリ金属の割合は任意であり、０≦ｘ≦１である。）で表されるニオブ／タンタル酸アルカリを含む結晶であることを特徴とする、ニオブ／タンタル酸アルカリ系膜の製造方法が提供される。 According to the first aspect of the present invention, the substrate is immersed, heated and pressurized in a water-containing solvent containing alkali hydroxide and amorphous niobium / tantalum oxide in a reaction vessel, Depositing a niobium / tantalate alkali-based film having a perovskite crystal structure on the substrate, wherein the niobium / tantalum-based oxide has an average compositional formula (Nb 1-x Ta x ) 2 O 5 (wherein Niobium oxide represented by 0 ≦ x ≦ 1), a single body of tantalum oxide, a solid solution or a mixture thereof, which may be a hydrate, the niobium / tantalate alkali based film has a formula A Nb 1-x Ta x ) O 3 (wherein, A is one or more alkali metals, and the ratio of two or more alkali metals is arbitrary, and 0 ≦ x ≦ 1). Niobium / tantalate alkali represented Characterized in that it is a crystal comprising manufacturing method of a niobium / tantalum alkali-based film is provided.
　上記のニオブ／タンタル酸アルカリ系膜の製造方法によれば、従来より厚膜のニオブ／タンタル酸アルカリ系配向膜の商業的な製造が可能にされる。また、以下に開示されるようにニオブ／タンタル酸アルカリ系配向膜の配向性を高めることも可能である。本発明の第二の側面によれば、６０μm以上、好ましくは７０μｍ以上（前記式中のＡ＝Ｋの場合、さらにはＡの９６モル％以上がカリウムである場合は、１１０μｍ以上、好ましくは１４０μｍ以上）からｍｍオーダーまでの膜厚を有するニオブ／タンタル酸アルカリ系配向膜及びそれを利用した新規な圧電又は焦電素子及び機能性装置が提供される。本発明は、ニオブ／タンタル酸アルカリ系配向膜の厚膜化におけるブレイクスルーを成すものである。 According to the above-mentioned method of producing a niobium / tantalate alkali based film, commercial production of a thick film of a niobium / tantalate based alkali oriented film can be made. In addition, as disclosed below, it is also possible to enhance the orientation of the niobium / tantalate alkali orientation film. According to the second aspect of the present invention, it is 60 μm or more, preferably 70 μm or more (when A = K in the above formula, furthermore, when 96 mol% or more of A is potassium, 110 μm or more, preferably 140 μm An alkali niobium / tantalate based alignment film having a film thickness from the above to mm order and a novel piezoelectric or pyroelectric element and functional device using the same are provided. The present invention constitutes a breakthrough in thickening of a niobium / tantalate alkali type alignment film.
　以下に本発明の第一の側面（以下では、単に本発明ともいう。）の代表的な実施態様あるいは好ましい実施態様のいくつかを例示すると、本発明のニオブ／タンタル酸アルカリ系膜の製造方法は、バッチ処理を繰り返してもよいが、１回のバッチ処理で堆積されるニオブ／タンタル酸アルカリ系膜の膜厚は、１μｍ以上、３μｍ以上、１０μｍ以上、１５μｍ以上、さらに２０μｍ以上であることができる。反応装置を大型化するなどの工夫をすれば、この膜厚はさらに厚くすることが可能である。 A method of producing a niobium / tantalate alkali based film of the present invention will be exemplified below by exemplifying some of the representative embodiments or preferred embodiments of the first aspect of the present invention (hereinafter also referred to simply as the present invention). The batch process may be repeated, but the film thickness of the niobium / tantalate alkali type film deposited in one batch process is 1 μm or more, 3 μm or more, 10 μm or more, 15 μm or more, and further 20 μm or more. Can. This film thickness can be further increased by increasing the size of the reaction apparatus.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、ニオブ／タンタル酸アルカリ系膜を堆積し、得られるニオブ／タンタル酸アルカリ系膜の膜厚が３μｍ以上、１０μｍ以上、２０μｍ以上、さらにそれ以上であることができる。特に、本発明の製造方法で得られるニオブ／タンタル酸アルカリ系膜は、好ましくは６０μm以上、７０μｍ以上、１００μｍ以上、１４０μｍ以上、１５０μｍ以上、２００μｍ以上、３００μｍ以上であることができ、さらには１ｍｍ以上あるいは２ｍｍ以上のｍｍオーダーであってよい。ニオブ／タンタル酸アルカリ系膜の膜厚の上限は用途及び経済性によって決めればよいが、例えば、数ｍｍ以下、１ｍｍ以下、５００μｍ以下、４００μｍ以下、３００μｍ以下でもよい。１つの好ましい態様において、得られるニオブ／タンタル酸アルカリ系膜の膜厚が６０μｍ以上であり、前記式Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３中のＡ＝Ｋの場合、さらにＡの９６モル％以上がカリウムである場合は１１０μｍ以上であることが好ましい。別の１つの好ましい態様において、得られるニオブ／タンタル酸アルカリ系膜の膜厚が７０μｍ以上であり、前記式Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３中のＡ＝Ｋの場合、さらにＡの９６モル％以上がカリウムである場合は１４０μｍ以上であることが好ましい。 In the method for producing a niobium / tantalate alkali type film of the present invention, the niobium / tantalate alkali type film is deposited, and the film thickness of the obtained niobium / tantalate alkali type film is 3 μm or more, 10 μm or more, 20 μm or more, It can be more than. In particular, the niobium / tantalate alkali type film obtained by the manufacturing method of the present invention can preferably have a size of 60 μm or more, 70 μm or more, 100 μm or more, 140 μm or more, 150 μm or more, 200 μm or more, 300 μm or more, and further 1 mm. It may be of the order of mm above or 2 mm or more. The upper limit of the film thickness of the niobium / tantalate alkali type film may be determined depending on the application and economy, but may be several mm or less, 1 mm or less, 500 μm or less, 400 μm or less, 300 μm or less, for example. In one preferred embodiment, when the film thickness of the obtained niobium / tantalate alkali-based film is 60 μm or more, and A = K in the above-mentioned formula A (Nb 1-x Ta x ) O 3 , further 96 moles of A When% or more is potassium, it is preferable that it is 110 micrometers or more. In another preferred embodiment, when the film thickness of the resulting niobium / tantalate alkali type film is 70 μm or more and A = K in the above-mentioned formula A (Nb 1-x Ta x ) O 3 , the value of A is further When 96 mol% or more is potassium, it is preferable that it is 140 micrometers or more.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、基体は平面及び／又は曲面を含む表面を有してよい。 In the method for producing a niobium / tantalate alkali based film of the present invention, the substrate may have a surface including a flat surface and / or a curved surface.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、基体上に堆積するニオブ／タンタル酸アルカリ系膜の量が、消費されるニオブ／タンタル系酸化物の１モルを基準として４ミリモル以上、又は消費されるニオブ／タンタル系酸化物の０．５質量％以上であることができる。さらには４．０質量％以上、２０質量％以上であってよい。 In the method of producing a niobium / tantalate alkali based film according to the present invention, the amount of the niobium / tantalate based alkali film deposited on the substrate is 4 mmol or more based on 1 mol of the niobium / tantalum based oxide consumed, Or it can be 0.5 mass% or more of the niobium / tantalum-based oxide consumed. Furthermore, it may be 4.0% by mass or more and 20% by mass or more.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、水酸化アルカリと非晶質ニオブ／タンタル系酸化物とのモル比は、例えば、１：１．０×１０－４～１：１．０×１０５、さらには１：１．０×１０－２～１：１．０×１０４であってよい。 In the method for producing a niobium / tantalate alkali based film of the present invention, the molar ratio of the alkali hydroxide to the amorphous niobium / tantalum based oxide is, for example, 1: 1.0 × 10 −4 to 1: 1. It may be 0 × 10 5 or even 1: 1.0 × 10 −2 to 1: 1.0 × 10 4 .
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、水酸化アルカリが、水酸化カリウム及び／又は水酸化ナトリウム及び／又は水酸化リチウム、特に水酸化カリウム及び／又は水酸化ナトリウムであってよい。 In the method for producing a niobium / tantalate alkali based film of the present invention, the alkali hydroxide may be potassium hydroxide and / or sodium hydroxide and / or lithium hydroxide, in particular potassium hydroxide and / or sodium hydroxide. .
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、原料に水酸化カリウム及び水酸化ナトリウムを含む場合、水酸化カリウムと水酸化ナトリウムとの合計に対する水酸化カリウムのモル比（[KOH]/([KOH]+[NaOH])）が、０．０～１．０、さらには０．６～１．０あるいは０．７５～１．０であってよい。 In the method for producing a niobium / tantalate alkali based film of the present invention, when potassium hydroxide and sodium hydroxide are contained in the raw material, the molar ratio of potassium hydroxide to the total of potassium hydroxide and sodium hydroxide ([KOH] / ([KOH] + [NaOH])) may be 0.0 to 1.0, further 0.6 to 1.0 or 0.75 to 1.0.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、水酸化カリウムと水酸化ナトリウムと水酸化リチウムとの合計に対する水酸化リチウムのモル比（[LiOH]/([KOH]+[NaOH]+[LiOH]）が、０～０．１であってよい。 In the method for producing a niobium / tantalate alkali based film of the present invention, the molar ratio of lithium hydroxide to the total of potassium hydroxide, sodium hydroxide and lithium hydroxide ([LiOH] / ([KOH] + [NaOH] + [LiOH]) may be from 0 to 0.1.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、水含有溶媒あるいは水中の水酸化アルカリの濃度は、例えば、０．１～３０モル／Ｌ、さらには０．１～２０モル／Ｌであってよい。 In the method for producing a niobium / tantalate alkali based film according to the present invention, the concentration of the water-containing solvent or the alkali hydroxide in the water is, for example, 0.1 to 30 mol / L, and further 0.1 to 20 mol / L. May be there.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、基体がペロブスカイト系の結晶構造を有してよい。 In the method of producing an alkali niobium / tantalate film according to the present invention, the substrate may have a perovskite crystal structure.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、基体が、半導体、金属、プラスチック、セラミックスから選ばれる材料からなり、表面にペロブスカイト系の結晶構造のバッファ層を有する基体であってよい。 In the method of producing an alkali niobium / tantalate film according to the present invention, the substrate may be made of a material selected from semiconductors, metals, plastics and ceramics, and the substrate may have a buffer layer of a perovskite crystal structure.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、基体が導電性基体であってよい。 In the method for producing a niobium / tantalate alkali based film of the present invention, the substrate may be a conductive substrate.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、ニオブ／タンタル酸アルカリ系膜は、ＣａＯ、ＣｕＯ、ＭｎＯ２、Ｓｂ２Ｏ３、ＢａＯ、ＺｒＯ２及びＴｉＯ2から選ばれる酸化物をさらに含むことができる。これらの酸化物はニオブ／タンタル酸アルカリに固溶できる酸化物であり、ニオブ／タンタル酸アルカリ系膜において固溶体であってよいが、混合物をなしていてよい。 In the method for producing a niobium / tantalate alkali type film of the present invention, the niobium / tantalate alkali type film further comprises an oxide selected from CaO, CuO, MnO 2 , Sb 2 O 3 , BaO, ZrO 2 and TiO 2. Can be included. These oxides are oxides that can be solid-solved in an alkali of niobium / tantalate, and may be a solid solution in the niobium / tantalate alkali film, but may be a mixture.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、反応容器が密封容器であり、反応容器内の温度を５０～３００℃の温度に加熱してよい。 In the method for producing an alkali niobium / tantalate film according to the present invention, the reaction vessel may be a sealed vessel, and the temperature in the reaction vessel may be heated to a temperature of 50 to 300.degree.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、反応容器が密封容器であり、反応容器内をマイクロ波を用いて加熱してよい。 In the method for producing a niobium / tantalate alkali based film of the present invention, the reaction vessel may be a sealed vessel, and the inside of the reaction vessel may be heated using a microwave.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、ニオブ／タンタル酸アルカリ系膜が一軸配向又はエピタキシャル配向した結晶を含むことができる。 In the method for producing a niobium / tantalate alkali type film of the present invention, the niobium / tantalate alkali type film can contain crystals uniaxially or epitaxially oriented.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、ニオブ／タンタル酸アルカリ系膜が自己分極（分極処理なしで分極方向が揃っている）していることができる。 In the method for producing a niobium / tantalate alkali type film of the present invention, the niobium / tantalate alkali type film can be self-polarized (the polarization directions are aligned without polarization treatment).
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、ニオブ／タンタル酸アルカリ系膜を、水中から取り出した後、１００～７５０℃の温度でアニールすることができる。 In the method for producing a niobium / tantalate alkali type film of the present invention, the niobium / tantalate alkali type film can be annealed at a temperature of 100 to 750 ° C. after being taken out of water.
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法において、ニオブ／タンタル酸アルカリ系膜が圧電体膜であることができる。 In the method for producing a niobium / tantalate alkali type film of the present invention, the niobium / tantalate alkali type film can be a piezoelectric film.
　本発明の第二の側面では、上記の製造方法で製造される一軸配向又はエピタキシャル配向したニオブ／タンタル酸アルカリ系膜であってよい。 In the second aspect of the present invention, the film may be a uniaxially or epitaxially oriented niobium / tantalate alkali based film produced by the above-mentioned production method.
　また、本発明の第二側面では、Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３（式中、Ａはアルカリ金属の１種または２種以上であり、２種以上のアルカリ金属の割合は任意であり、０≦ｘ≦１である。）で表され、一軸配向又はエピタキシャル配向した結晶を含むニオブ／タンタル酸アルカリ系膜であって、前記ニオブ／タンタル酸アルカリ系膜が、６０μm以上、好ましくは７０μm以上（ただし、Ａ＝Ｋの場合、さらにはＡの９６モル％以上がカリウムである場合は、１１０μｍ以上、好ましくは１４０μｍ以上）の厚さを有するか及び／又は曲面を含む基体上に形成されていることを特徴とするニオブ／タンタル酸アルカリ系膜であってよい。 In the second aspect of the present invention, A (Nb 1-x Ta x ) O 3 (wherein A is one or two or more alkali metals, and the ratio of two or more alkali metals is arbitrary. And a niobium / tantalate alkali type film containing crystals uniaxially or epitaxially oriented, wherein the niobium / tantalate alkali type film is 60 μm or more, preferably 70 μm or more (however, when A = K, furthermore, when 96 mol% or more of A is potassium, it is 110 μm or more, preferably 140 μm or more) and / or formed on a substrate including a curved surface It may be a niobium / tantalate alkali based film characterized in that
　本発明の第二の側面（以下、単に本発明ともいう。）のニオブ／タンタル酸アルカリ系膜において、ニオブ／タンタル酸アルカリ系膜が自己分極（分極処理なしで分極方向が揃っている）していることができる。 In the niobium / tantalate alkali type film of the second aspect of the present invention (hereinafter, also simply referred to as the present invention), the niobium / tantalate alkali type film is self-polarized (the polarization directions are aligned without polarization treatment). Can be.
　本発明のニオブ／タンタル酸アルカリ系膜において、ニオブ／タンタル酸アルカリ系膜がペロブスカイト系の結晶構造を有する基体上に形成されていることができる。 In the niobium / tantalate alkali type film of the present invention, the niobium / tantalate alkali type film can be formed on a substrate having a perovskite crystal structure.
　本発明のニオブ／タンタル酸アルカリ系膜において、基体がニオブ／タンタル酸アルカリ系膜と接する導電性表面を有することができる。 In the niobium / tantalate alkali type film of the present invention, the substrate can have a conductive surface in contact with the niobium / tantalate alkali type film.
　本発明のニオブ／タンタル酸アルカリ系膜において、基体が半導体、金属、プラスチック、セラミックスから選ばれる材料を含み、その材料とニオブ／タンタル酸アルカリ系膜との間にペロブスカイト構造のバッファ層を有する基体であることができる。 In the niobium / tantalate alkali type film of the present invention, the base includes a material selected from semiconductors, metals, plastics, and ceramics, and a base having a buffer layer of a perovskite structure between the material and the niobium / tantalate alkali type film. Can be.
　また、本発明の第二側面では、圧電特性を利用する機能性装置であって、圧電素子が上記のニオブ／タンタル酸アルカリ系膜と電極とを含む圧電素子を含み、機能性装置が、医療用超音波プローブ、超音波トランスミッタ、超音波センサ、焦電発電装置、振動発電装置、アクチュエータから選ばれることを特徴とする機能性装置であってよい。 Further, according to the second aspect of the present invention, there is provided a functional device utilizing piezoelectric characteristics, wherein the piezoelectric device includes a piezoelectric device including the above-mentioned niobium / tantalate alkali type film and an electrode, and the functional device is a medical device. The functional device may be selected from an ultrasonic probe, an ultrasonic transmitter, an ultrasonic sensor, a pyroelectric generator, a vibration generator, and an actuator.
　本発明の機能性装置は、２～１００ＭＨｚの超音波を発信又は受信できる超音波プローブ用トランスデューサを含むことができる。 The functional device of the present invention can include a transducer for an ultrasonic probe capable of transmitting or receiving ultrasonic waves of 2 to 100 MHz.
　本発明の機能性装置は、超音波プローブ用トランスデューサを用いて、皮膚の表面下深度２０ｍｍ以内の領域を画像診断することができる超音波造影装置であることができる。 The functional device of the present invention can be an ultrasonic imaging device capable of diagnostic imaging of an area within a depth of 20 mm below the surface of the skin using a transducer for an ultrasonic probe.
　本発明の機能性装置は、超音波プローブ用トランスデューサを用いて、人体の組織に対して医療的処置を行うことができる医療用装置であることができる。 The functional device of the present invention can be a medical device capable of performing medical treatment on human tissue using an ultrasonic probe transducer.
　本発明の機能性装置は、２００Ｈｚ以下の共振周波数において１μＷ・Ｇ－２・ｍｍ－３以上の出力電力密度を有する発電装置であることができる。 The functional device of the present invention can be a power generator having an output power density of 1 μW · G −2 · mm −3 or more at a resonant frequency of 200 Hz or less.
　本発明の第一の側面及び第二の側面において、上記の各態様は任意に組み合わせられることが理解されるべきである（請求の範囲の記載が参照される）。 In the first and second aspects of the present invention, it should be understood that the above-described aspects may be combined arbitrarily (see the claims).
　本発明のニオブ／タンタル酸アルカリ系膜の製造方法によれば、水熱合成法を用いて、従来得られていたニオブ／タンタル酸アルカリ系膜と同等の結晶性及び圧電特性を有するニオブ／タンタル酸アルカリ系膜を製膜し、従来の出発原料から製膜できる膜厚と比べて、同様の製造条件において、得られる膜厚を増加させ、析出効率を向上することができる。また、得られるニオブ／タンタル酸アルカリ系膜の配向性を向上させることもできる。
　また、本発明によれば、従来提供されていない膜厚のニオブ／タンタル酸アルカリ系配向膜が提供される。さらに、従来と比べて低周波数、高出力の圧電又は焦電素子など、その圧電又は焦電特性を利用して新しい用途（例えば、人体の皮膚表面近傍の画像診断などの医療用途）のための機能性装置が提供される。 According to the method for producing a niobium / tantalate alkali based film of the present invention, a niobium / tantalum having the same crystallinity and piezoelectric properties as conventionally obtained niobium / tantalate alkali based films using a hydrothermal synthesis method The film thickness obtained can be increased and the deposition efficiency can be improved under the same manufacturing conditions as compared with the film thickness that can be formed from an acid alkali film and formed from conventional starting materials. In addition, the orientation of the obtained niobium / tantalate alkali type film can be improved.
Further, according to the present invention, an alkali niobium / tantalate based alignment film having a film thickness not provided conventionally is provided. Furthermore, for new applications (for example, medical applications such as diagnostic imaging in the vicinity of the skin surface of the human body) utilizing its piezoelectric or pyroelectric properties, such as piezoelectric or pyroelectric elements having lower frequency and higher output than conventional ones. A functional device is provided.
図１は、本発明のニオブ／タンタル酸アルカリ系膜の製造方法に用いる反応装置の例の模式断面図である。FIG. 1 is a schematic cross-sectional view of an example of a reaction apparatus used in the method for producing a niobium / tantalate alkali based film of the present invention. 図２は、模式的な圧電体素子１０を示す横断面図である。FIG. 2 is a cross-sectional view showing a schematic piezoelectric element 10. 図３は、超音波プローブ１の例を模式的に示す。FIG. 3 schematically shows an example of the ultrasonic probe 1. 図４は、焦電発電装置１０の例を模式的に示す。FIG. 4 schematically shows an example of the pyroelectric power generation system 10. 図５（ａ）（ｂ）は、実施例及び比較例で用いた原料の非晶質Nb2O5及び結晶Nb2O5のＸ線回折チャートである。FIGS. 5 (a) and 5 (b) are X-ray diffraction charts of amorphous Nb 2 O 5 and crystalline Nb 2 O 5 used as raw materials in Examples and Comparative Examples. 図６は、実施例１及び比較例１で得られたKNN膜のＸ線回折チャートである。（ａ）及び（ｂ）は実施例１及び比較例１それぞれの膜厚10μｍ及び5μｍのKNN膜、（ｃ）及び（ｄ）は実施例及び比較例で同じ膜厚２μｍのKNN膜についてのＸ線回折チャートである。FIG. 6 is an X-ray diffraction chart of the KNN films obtained in Example 1 and Comparative Example 1. (A) and (b) show 10 nm and 5 μm thick KNN films of Example 1 and Comparative Example 1 respectively, and (c) and (d) show X of the same 2 nm thick KNN film as Example and Comparative example. It is a line diffraction chart. 図７（ａ）（ｂ）は、実施例１～２及び比較例１～２で得られたKNN膜の膜厚と反応時間との関係を示すグラフである。FIGS. 7A and 7B are graphs showing the relationship between the film thickness of the KNN films obtained in Examples 1 and 2 and Comparative Examples 1 and 2 and the reaction time. 図８は、実施例１及び比較例１で得られたKNN膜の微細構造を観察したSEM写真である。（ａ）及び（ｂ）は比較例１で得られた膜厚２μｍ及び５μｍのKNN膜、（ｃ）及び（ｄ）は実施例１で得られた膜厚２μｍ及び10μｍのKNN膜である。FIG. 8 is a SEM photograph of the microstructures of the KNN films obtained in Example 1 and Comparative Example 1. (A) and (b) are KNN films of 2 μm and 5 μm thickness obtained in Comparative Example 1, and (c) and (d) are KNN films of 2 μm and 10 μm thickness obtained in Example 1. 図９は、実施例１及び比較例１で得られたKNN膜の微細構造（平面）及び膜厚（横断面）を観察したSEM写真である。（ａ）及び（ｂ）は比較例１で得られた膜厚５μｍのKNN膜、（ｃ）及び（ｄ）は実施例１で得られた膜厚10μｍのKNN膜であり、（a）及び（ｃ）は微細構造（平面）、（ｂ）及び（ｄ）は膜厚（横断面）を観察している。FIG. 9 is a SEM photograph obtained by observing the fine structure (plane) and the film thickness (cross section) of the KNN films obtained in Example 1 and Comparative Example 1. (A) and (b) are KNN films with a film thickness of 5 μm obtained in Comparative Example 1, (c) and (d) are KNN films with a film thickness of 10 μm obtained in Example 1, (a) and (b) In (c), the microstructure (plane) is observed, and in (b) and (d), the film thickness (cross section) is observed. 図１０は、実施例及び比較例で得られたKNN膜における原料のアルカリ比とKNN膜のアルカル比との対応関係を示すグラフである。FIG. 10 is a graph showing the correspondence between the alkali ratio of the raw material in the KNN film obtained in the example and the comparative example and the alcal ratio of the KNN film. 図１１は、実施例及び比較例で得られたKNN膜における原料のアルカリ比とKNN膜の膜厚との対応関係を示すグラフである。FIG. 11 is a graph showing the correspondence between the alkali ratio of the raw material in the KNN film obtained in the example and the comparative example and the film thickness of the KNN film. 図１２は、実施例８で得られたKNN膜のSEM断面写真を示す。FIG. 12 shows a SEM cross-sectional photograph of the KNN film obtained in Example 8. 図１３は、実施例１～２及び比較例１～２で得られたKNN膜の膜厚と反応時間との関係を示す別のグラフである。（ａ）は、アルカリ濃度7mol/Lの実施例１及び比較例１で得られたKNN膜、（ｂ）は、アルカリ濃度6mol/Lの実施例２及び比較例２で得られたKNN膜である。FIG. 13 is another graph showing the relationship between the film thickness of the KNN films obtained in Examples 1 and 2 and Comparative Examples 1 and 2 and the reaction time. (A) shows the KNN films obtained in Example 1 and Comparative Example 1 at an alkali concentration of 7 mol / L, and (b) shows the KNN films obtained in Example 2 and Comparative Example 2 at an alkali concentration of 6 mol / L. is there. 図１４は、実施例及び比較例の圧電素子の比誘電率及び誘電損失を示すグラフである。FIG. 14 is a graph showing the relative dielectric constants and dielectric losses of the piezoelectric elements of the example and the comparative example. 図１５は、実施例及び比較例の圧電素子の誘電分極ヒステリシス曲線を示すグラフである。FIG. 15 is a graph showing dielectric polarization hysteresis curves of the piezoelectric elements of the example and the comparative example. 図１６は、実施例及び比較例の圧電素子の電界誘起歪を示すグラフである。FIG. 16 is a graph showing the electric field induced strain of the piezoelectric element of the example and the comparative example. 図１７は、KNN膜の堆積後(as depo.)膜と600℃熱処理膜について発電特性とx=K/(K+Na)比との関係を示す。FIG. 17 shows the relationship between the power generation characteristics and the x = K / (K + Na) ratio for the film after deposition (as depo.) Of the KNN film and the heat-treated film at 600 ° C. 図１８は、実施例及び比較例の圧電素子におけるアニール温度と誘電分極ヒステリシス曲線との関係を示すグラフである。（ａ）は堆積後、（ｂ）～（ｅ）はアニール温度が異なる。FIG. 18 is a graph showing the relationship between the annealing temperature and the dielectric polarization hysteresis curve in the piezoelectric elements of the example and the comparative example. After deposition, (b) to (e) have different annealing temperatures. 図１９は、実施例及び比較例の圧電素子におけるアニール温度と電界誘起歪特性との関係を示すグラフである。（ａ）は堆積後、（ｂ）～（ｅ）はアニール温度が異なる。FIG. 19 is a graph showing the relationship between the annealing temperature and the electric field induced strain characteristic in the piezoelectric elements of the example and the comparative example. After deposition, (b) to (e) have different annealing temperatures. 図２０（ａ）（ｂ）は、それぞれ比較例及び実施例の圧電素子におけるアニール温度と比誘電率及び誘電損失との関係を示すグラフである。FIGS. 20 (a) and 20 (b) are graphs showing the relationship between the annealing temperature and the relative dielectric constant and the dielectric loss in the piezoelectric element of the comparative example and the example, respectively. 図２１は、実施例１４で得られたKNN膜の膜厚を結晶質酸化ニオブを用いた場合と比較して示す。FIG. 21 shows the thickness of the KNN film obtained in Example 14 in comparison with the case of using crystalline niobium oxide. 図２２（ａ）（ｂ）は、結晶質酸化タンタルのＸ線回折チャート及びSEM写真、図２２（ｃ）（ｄ）は、実施例１６で得られた非晶質酸化タンタルのＸ線回折チャート及びSEM写真を示す。22 (a) and 22 (b) are X-ray diffraction charts and SEM photographs of crystalline tantalum oxide, and FIGS. 22 (c) and 22 (d) are X-ray diffraction charts of amorphous tantalum oxide obtained in Example 16. And a SEM photograph. 図２３（ａ）は、実施例１８及び比較例１１で得られたKNN膜のＸ線回析チャートを示し、図２３（ｂ）は、実施例１及び比較例１で得られたKNN膜のＸ線回析チャートを示す。FIG. 23 (a) shows X-ray diffraction charts of the KNN films obtained in Example 18 and Comparative Example 11, and FIG. 23 (b) shows the KNN films obtained in Example 1 and Comparative Example 1. The X-ray diffraction chart is shown. 図２４は、実施例１９で得られたKNN膜のX線回析結果を示す。FIG. 24 shows the results of X-ray diffraction of the KNN film obtained in Example 19. 図２５は、実施例２０で得られたKNNT配向膜のNb/(Nb+Ta)比及びK/(K+Na)比を示す。FIG. 25 shows the Nb / (Nb + Ta) ratio and the K / (K + Na) ratio of the KNNT alignment film obtained in Example 20. 図２６は、実施例２２で得られたKNLNT膜の圧電特性を示す。FIG. 26 shows the piezoelectric characteristics of the KNLNT film obtained in Example 22. 図２７は、as depo.のKNN膜と600℃で熱処理したKNN膜を用いた圧電素子のP-Eヒステリシス曲線と、電界に対するe31,fを示す。FIG. 27 shows PE hysteresis curves of piezoelectric elements using a KNN film of as depo. And a KNN film heat-treated at 600 ° C., and e 31, f with respect to an electric field. 図２８は、as depo.のKNN膜と600℃で熱処理したKNN膜を用いた圧電素子の分極処理電界に対するe31,fを示す。FIG. 28 shows the e 31, f with respect to the polarization treatment electric field of the piezoelectric element using the KNN film of as depo. And the KNN film heat-treated at 600 ° C. 図２９は、KNN膜のe31,fの膜厚との関係を示す。FIG. 29 shows the relationship between the film thickness of e 31 and f of the KNN film. 図３０は、as depo.のKNN膜と600℃で熱処理したKNN膜を用いた圧電素子のAFM(ｄ33)を示す。FIG. 30 shows AFM (d 33 ) of a piezoelectric element using a KNN film of as depo. And a KNN film heat-treated at 600 ° C. 図３１の上図は、熱処理温度を変えたときのP-Eヒステリシス曲線のシフト量の変化を示す。as depo.のKNN膜から熱処理温度が上昇するに従い、シフト量が減少している。図３１の下図は、膜中の水の量とP-Eヒステリシス曲線のシフト量との関係を示す。The upper part of FIG. 31 shows the change of the shift amount of the PE hysteresis curve when the heat treatment temperature is changed. As the heat treatment temperature increases from the as depo. KNN film, the shift amount decreases. The lower part of FIG. 31 shows the relationship between the amount of water in the membrane and the shift amount of the PE hysteresis curve. 図３２は、格子内OH-の量と（ａ）製膜温度及び（ｂ）水含有溶媒との関係を示す。FIG. 32 shows the relationship between the amount of OH − in the lattice, (a) the film-forming temperature and (b) the water-containing solvent. 図３４は、実施例２６で観測された発電特性の変化と、圧電素子の基礎特性から計算される出力電力の変化（破線）を示す。FIG. 34 shows the change in the power generation characteristics observed in Example 26, and the change in output power (broken line) calculated from the basic characteristics of the piezoelectric element. 図３４は、マイクロ波加熱可能な反応装置を模式的に示す。FIG. 34 schematically shows a microwave-heatable reactor.
　（ニオブ／タンタル酸アルカリ系膜の製造方法）
　本発明の第一の側面は、反応容器内において、水酸化アルカリと、非晶質ニオブ／タンタル系酸化物とを含む水含有溶媒中に、基体を浸漬し、加熱及び加圧して、基体上にペロブスカイト系の結晶構造を有するニオブ／タンタル酸アルカリ系膜を堆積すること、前記ニオブ／タンタル系酸化物は、平均組成式（Ｎｂ１－ｘＴａｘ）２Ｏ５（式中、０≦ｘ≦１である。）で表される酸化ニオブ、酸化タンタルの単体、固溶体またはそれらの混合物であり、それらは水和物でもよく、前記ニオブ／タンタル酸アルカリ系膜は、Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３（式中、Ａはアルカリ金属の１種または２種以上であり、２種以上のアルカリ金属の割合は任意であり、０≦ｘ≦１である。）で表されるニオブ／タンタル酸アルカリを含む結晶であることを特徴とするニオブ／タンタル酸アルカリ系膜の製造方法にある。 (Production method of niobium / tantalate alkali type film)
According to a first aspect of the present invention, a substrate is immersed in a water-containing solvent containing an alkali hydroxide and an amorphous niobium / tantalum oxide in a reaction vessel, heated and pressed, on the substrate. Depositing a niobium / tantalate alkali-based film having a perovskite crystal structure, the niobium / tantalum-based oxide has an average composition formula (Nb 1-x Ta x ) 2 O 5 (wherein 0 ≦ x Niobium oxide represented by 、 1), a single body of tantalum oxide, a solid solution or a mixture thereof, which may be a hydrate, and the niobium / tantalate alkali based film is A (Nb 1 -x Niobium represented by Ta x ) O 3 (wherein, A represents one or more alkali metals, and the ratio of two or more alkali metals is arbitrary, and 0 ≦ x ≦ 1). / With crystals containing alkali metal tantalate In the production method of a niobium / tantalum alkali-based film, characterized in Rukoto.
　図１に、本発明のニオブ／タンタル酸アルカリ系膜の製造方法に用いる反応装置の例の断面を模式的に示す。図１において、密閉式の反応容器１内には水含有溶媒、ここでは水２が収容され、水２の中には水酸化ナトリウム、水酸化カリウムなどの水酸化アルカリが溶解されているとともに、非晶質ニオブ／タンタル系酸化物３がこの例では粉末として添加されている。また、反応容器１には上方から基体４が懸下されて、水（アルカリ水溶液）２に浸漬されている。 FIG. 1 schematically shows a cross section of an example of a reaction apparatus used in the method for producing a niobium / tantalate alkali based film of the present invention. In FIG. 1, a water-containing solvent, here, water 2 is contained in a closed reaction vessel 1, and in the water 2, an alkali hydroxide such as sodium hydroxide or potassium hydroxide is dissolved. Amorphous niobium / tantalum oxide 3 is added as a powder in this example. Further, the base 4 is suspended from above in the reaction vessel 1 and immersed in water (alkaline aqueous solution) 2.
　図１に示す反応装置において、密閉式の反応容器１を加熱すると、反応容器１の内部は加熱されると加圧状態になり、非晶質ニオブ／タンタル系酸化物のアルカリ水溶液２への溶解度が増加して、次第にアルカリ水溶液２に溶解するとともに、不均一反応により、基体４の表面にニオブ／タンタル酸アルカリの不均一核が生成し、さらにその上へのニオブ／タンタル酸アルカリの堆積が進んで基体４の表面にニオブ／タンタル酸アルカリ系膜が形成される。 In the reaction apparatus shown in FIG. 1, when the closed reaction vessel 1 is heated, the inside of the reaction vessel 1 is heated and becomes pressurized, and the solubility of the amorphous niobium / tantalum oxide in the alkaline aqueous solution 2 The solution is gradually dissolved in the aqueous alkaline solution 2 and the heterogeneous reaction causes the formation of heterogeneous nuclei of niobium / alkali tantalate on the surface of the substrate 4 and further the deposition of the alkali of niobium / tanalolate thereon. Then, a niobium / tantalate alkali type film is formed on the surface of the substrate 4.
　本発明において、反応容器は、水含有溶媒と、その水含有溶媒中に水酸化アルカリと非晶質ニオブ／タンタル系酸化物とを含み、反応容器内部を加熱及び加圧できる密閉式の容器であるが、オートクレーブと呼ばれる容器であることができる。反応容器は、また、容器内の水含有溶媒中に１又は複数の基体を浸漬できる構造を有するが、基体の保持方法は限定されず、例えば、容器の蓋に設置された取付具５に取り付けられる構造であることができる。水含有溶媒中に浸漬される基体４の方向などは縦、横など適宜設定することができる。 In the present invention, the reaction vessel is a closed vessel that contains a water-containing solvent, an alkali hydroxide and an amorphous niobium / tantalum oxide in the water-containing solvent, and can heat and pressurize the inside of the reaction vessel. It can be a container called an autoclave. The reaction container also has a structure capable of immersing one or more substrates in the water-containing solvent in the container, but the method of holding the substrates is not limited, and for example, attached to the fixture 5 installed on the lid of the container Can be a structure. The direction, etc., of the substrate 4 to be immersed in the water-containing solvent can be set as appropriate, such as vertical or horizontal.
　本発明で用いる水含有溶媒は、水を含む溶媒であり、水のほか、水と有機溶媒との混合溶媒であってよいが、特にイオン交換水が好ましい。水と混合して用いる有機溶媒としては、アルコール、ケトン、カルボン酸,エーテルなど水と溶解性あるいは混和性のある有機溶媒が好ましい。溶媒中の水含有量を少なくすることで、水熱合成において生成物中の最も懸念される不純物である格子内ＯＨイオンの量を低減することができる。また、水含有溶媒を用い、溶媒中の水の濃度を変えることで、生成するニオブ／タンタル酸アルカリ系膜に取り込まれる水（OHイオン)の量を変えることができ、ニオブ／タンタル酸アルカリ系膜の自己分極の程度を制御できる。なお、取り込まれる水（ＯＨ－）の量は、製膜温度を高くして、低減すること、制御することができる。 The water-containing solvent used in the present invention is a solvent containing water, and may be a mixed solvent of water and an organic solvent in addition to water, but ion-exchanged water is particularly preferable. As an organic solvent to be used by mixing with water, an organic solvent which is soluble or miscible with water, such as alcohol, ketone, carboxylic acid, ether or the like is preferable. By reducing the water content in the solvent, it is possible to reduce the amount of intra-lattice OH ions, which are the most concerned impurities in the product in hydrothermal synthesis. In addition, by changing the concentration of water in the solvent using a water-containing solvent, it is possible to change the amount of water (OH ion) incorporated into the niobium / tantalate alkali type film to be produced. The degree of self polarization of the membrane can be controlled. The amount of water (OH − ) to be taken in can be controlled by increasing the film forming temperature and reducing it.
　本発明で用いる水酸化アルカリとしては、水酸化リチウム、水酸化ナトリウム、水酸化カリウム、水酸化ルビジウム、水酸化セシウム、水酸化フランシウムのいずれでもよいが、水酸化ナトリウム、水酸化カリウム、水酸化リチウムのいずれか１種以上、特に水酸化ナトリウムと水酸化カリウムの混合物、及び水酸化ナトリウムと水酸化カリウムと水酸化リチウムの混合物が好ましい。水酸化アルカリとして水酸化カリウムと水酸化ナトリウムの両方を含むと、圧電特性の向上、絶縁性の向上、析出速度の向上で好ましい。 The alkali hydroxide used in the present invention may be any of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide and francium hydroxide, but sodium hydroxide, potassium hydroxide and lithium hydroxide And mixtures of sodium hydroxide and potassium hydroxide, and mixtures of sodium hydroxide, potassium hydroxide and lithium hydroxide. It is preferable to include both potassium hydroxide and sodium hydroxide as the alkali hydroxide in view of the improvement of the piezoelectric characteristics, the improvement of the insulating property, and the improvement of the deposition rate.
　水酸化ナトリウム及び／又は水酸化カリウム及び／又は水酸化リチウムを用いる場合、水酸化ナトリウムと水酸化カリウムの合計に対する水酸化カリウムのモル比（[KOH]/([KOH]+[NaOH])）は、０．０～１．０の全範囲であることができる。図１０に示されるように、この原料のアルカリモル比と生成物のアルカリモル比とは、正比例関係ではなく、特定の範囲で生成物のアルカリモル比が急激に増加する特異な比例関係を示すが、原料のアルカリモル比の全範囲において生成物のアルカリモル比が単調増加する関係にある。しかし、図１１に示されるように、原料の上記アルカリモル比の０．０～１．０の全範囲において、本発明による膜厚の増加を観察することができた。 When using sodium hydroxide and / or potassium hydroxide and / or lithium hydroxide, the molar ratio of potassium hydroxide to the total of sodium hydroxide and potassium hydroxide ([KOH] / ([KOH] + [NaOH])) Can range from 0.0 to 1.0. As shown in FIG. 10, the alkali molar ratio of the raw material and the alkali molar ratio of the product are not in direct proportion, but show a unique proportion relationship in which the alkali molar ratio of the product sharply increases in a specific range. However, in the whole range of the alkali molar ratio of the raw material, the alkali molar ratio of the product is in a relation of monotonously increasing. However, as shown in FIG. 11, an increase in film thickness according to the present invention could be observed in the entire range of 0.0 to 1.0 of the above-mentioned alkali molar ratio of the raw material.
　原料の水酸化ナトリウムと水酸化カリウムのモル比（[KOH]/([KOH]+[NaOH]))は、０．６～１．０の範囲、さらには０．７５～１．０の範囲であることは好ましい。これらの好ましい範囲において、ニオブ／タンタル酸アルカリ系膜の製膜厚さが特に大きいことが可能である（図１０参照）。また、原料の上記アルカリモル比が、例えば、０．０～１．０の範囲、さらには０．６～１．０、特に０．７５～０．９５の範囲であると、薄膜をセンサ・アクチュエータの用途に用いる上で好ましい。水酸化ナトリウムと水酸化カリウムと水酸化リチウムの混合物においても、水酸化ナトリウムと水酸化カリウムのモル比（[KOH]/([KOH]+[NaOH]))は、０．６～１．０の範囲、さらには０．７５～１．０の範囲であることが好ましい。 The molar ratio of sodium hydroxide to potassium hydroxide ([KOH] / ([KOH] + [NaOH])) of the raw material is in the range of 0.6 to 1.0, and further in the range of 0.75 to 1.0 Is preferred. Within these preferable ranges, the film thickness of the niobium / tantalate alkali type film can be particularly large (see FIG. 10). In addition, when the above-mentioned alkali molar ratio of the raw material is, for example, in the range of 0.0 to 1.0, and further in the range of 0.6 to 1.0, and particularly 0.75 to 0.95, It is preferable to use for the application of an actuator. Also in the mixture of sodium hydroxide, potassium hydroxide and lithium hydroxide, the molar ratio ([KOH] / ([KOH] + [NaOH])) of sodium hydroxide and potassium hydroxide is 0.6 to 1.0. It is more preferable that the range is from 0.75 to 1.0.
　水酸化ナトリウム及び／又は水酸化カリウム及び／又は水酸化リチウムを用いる場合、水酸化ナトリウムと水酸化カリウムと水酸化リチウムの合計に対する水酸化リチウムのモル比（[LiOH]/([KOH]+[NaOH]+[LiOH])）は、例えば０～０．５、さらには０～０．１、０～０．０５、０～０．０３であってよい。 When using sodium hydroxide and / or potassium hydroxide and / or lithium hydroxide, the molar ratio of lithium hydroxide to the total of sodium hydroxide, potassium hydroxide and lithium hydroxide ([LiOH] / ([KOH] + [[KOH] + [[ NaOH] + [LiOH]) may be, for example, 0 to 0.5, further 0 to 0.1, 0 to 0.05, 0 to 0.03.
　本発明で用いる水中の水酸化アルカリの濃度は、０．１～３０モル／Ｌ、０．１～２０モル／Ｌ、１～１０モル／Ｌ、特に３～８モル／Ｌであってよく、これらの範囲の上限値及び下限値は独立して組み合わせてもよい。水酸化アルカリの濃度がこれらの範囲内であると、ニオブ／タンタル系酸化物との反応性が高くなり、ニオブ／タンタル酸アルカリ系膜の核生成及び堆積速度が高く、また膜厚も大きくできると考えられる。 The concentration of alkali hydroxide in water used in the present invention may be 0.1 to 30 mol / L, 0.1 to 20 mol / L, 1 to 10 mol / L, particularly 3 to 8 mol / L. The upper limit value and the lower limit value of these ranges may be combined independently. When the concentration of the alkali hydroxide is within these ranges, the reactivity with the niobium / tantalum oxide becomes high, the nucleation and deposition rate of the niobium / tantalate alkali type film can be high, and the film thickness can be increased. it is conceivable that.
　本発明において、水酸化アルカリは反応（加熱・加圧）時に反応容器内の水（以下の記載では、水は水含有溶媒であってもよい。）に溶解していればよく、反応容器に注入する水に予め溶解させてもよいし、反応容器に収容されている水に添加して溶解させてもよいし、その組合せでもよい。 In the present invention, the alkali hydroxide may be dissolved in water in the reaction vessel (in the following description, water may be a water-containing solvent) at the time of reaction (heating / pressurization). It may be previously dissolved in the water to be injected, may be added to the water contained in the reaction vessel to be dissolved, or a combination thereof.
　本発明の第一の側面で用いる非晶質ニオブ／タンタル系酸化物は、平均組成式が（Ｎｂ１－ｘＴａｘ）２Ｏ５（式中、０≦ｘ≦１である。）で表される酸化物の単体、固溶体またはそれらの混合物をいうが、これらは水和物でもよい。 The amorphous niobium / tantalum-based oxide used in the first aspect of the present invention has an average composition formula of (Nb 1-x Ta x ) 2 O 5 (wherein 0 ≦ x ≦ 1). Oxides, solid solutions or mixtures thereof, which may be hydrates.
　本発明の第一の側面で用いるニオブ／タンタル系酸化物は、結晶質ではなく、非晶質であることを特徴とする。本発明では、従来の結晶質のニオブ／タンタル系酸化物ではなく、非晶質ニオブ／タンタル系酸化物を用いると、理由は不明であるが、驚くべきことに、結晶質を用いた場合と比べて、その他は同じ条件において基体上に堆積できるニオブ／タンタル酸アルカリ系膜の膜厚及び析出効率が、顕著に向上することを見出した（実施例参照）。ただし、本発明の製造方法において、非晶質ニオブ／タンタル系酸化物とともに結晶質ニオブ／タンタル系酸化物を用いることは必要ではないが、排除されない。 The niobium / tantalum-based oxide used in the first aspect of the present invention is characterized in that it is not crystalline but is amorphous. In the present invention, when the amorphous niobium / tantalum-based oxide is used instead of the conventional crystalline niobium / tantalum-based oxide, the reason is unclear, but, surprisingly, the case where the crystalline is used and In comparison, the inventors have found that the film thickness and the deposition efficiency of the niobium / tantalate alkali type film which can be deposited on the substrate under the same conditions as the others are significantly improved (see Examples). However, in the production method of the present invention, it is not necessary to use the crystalline niobium / tantalum oxide together with the amorphous niobium / tantalum oxide, but it is not excluded.
　ニオブ／タンタル系酸化物が非晶質であることは、Ｘ線回析によりニオブ／タンタル系酸化物の特性ピークが認められないことによって確認される。ニオブ／タンタル系酸化物の特性ピークが認められないとは、粉末Ｘ線回折測定結果より明確なピークが存在せずにハローが存在することをいう(図５参照）。 The amorphous nature of the niobium / tantalum-based oxide is confirmed by the fact that the characteristic peak of the niobium / tantalum-based oxide is not recognized by X-ray diffraction. The absence of a characteristic peak of the niobium / tantalum-based oxide means that a halo is present without a clear peak from the result of powder X-ray diffraction measurement (see FIG. 5).
　非晶質ニオブ／タンタル系酸化物は、例えば、N. Kumada et al., “Hydrothermal synthesis of NaNbO3--morphology change by starting compounds--, Journal of the Chemical Society of Japan 119(6)483-485 2011に記載されている製造方法によって製造できる。すなわち、非晶質ニオブ／タンタル系酸化物は、容器内で酸化ニオブ／タンタルに炭酸カリウムなどのアルカリを加え加熱して溶融させる。それらを冷却させた後、得られる（白色）粉末または塊を純水に溶かす。溶解しないものをろ紙で取り除き、ろ液にHNO3などの酸の水溶液を加え、（白色）粉末を沈殿させる。これらの沈殿した粉末をろ過し、蒸留水で洗浄した後、乾燥させる。この方法で合成した非晶質ニオブ／タンタル系酸化物は水和物であるが、乾燥機を用いて例えば200℃、24時間放置すると、得られた粉末は非水和物になる（Ｘ線回析による確認のほか、熱重量分析との減量と一致も確認される）。 Amorphous niobium / tantalum-based oxides are described, for example, in N. Kumada et al., “Hydrothermal synthesis of NaNbO 3 --morphology change by starting compounds--, Journal of the Chemical Society of Japan 119 (6) 483-485. It can be manufactured by the manufacturing method described in 2011. That is, an amorphous niobium / tantalum-based oxide is heated and melted by adding alkali such as potassium carbonate to niobium oxide / tantalum in a container and cooling them. After that, the resulting (white) powder or lump is dissolved in pure water, the undissolved one is removed with filter paper, and an aqueous solution of acid such as HNO 3 is added to the filtrate to precipitate the (white) powder. The powder is filtered, washed with distilled water, and dried.The amorphous niobium / tantalum oxide synthesized by this method is a hydrate, but when it is allowed to stand at 200 ° C. for 24 hours using a drier, for example. , The obtained powder is non-hydrated (In addition to confirmation by X-ray diffraction, the same loss as thermogravimetric analysis is also confirmed).
　非晶質ニオブ／タンタル系酸化物の固溶体を作製する場合、原料として用いる結晶質のニオブ／タンタル系酸化物は、融解させるので、固溶体である必要はなく、酸化ニオブと酸化タンタルの混合物でよい。 When preparing a solid solution of amorphous niobium / tantalum oxide, the crystalline niobium / tantalum oxide used as a raw material is melted, so it is not necessary to be a solid solution, and a mixture of niobium oxide and tantalum oxide may be used. .
　また、反応容器内に添加する非晶質ニオブ／タンタル系酸化物は、ニオブ／タンタル酸アルカリ系膜の意図する組成を実現するための平均組成を満たす限り、固溶体と混合物とで相違はない。原料組成の制御という観点からは酸化ニオブと酸化タンタルとの混合物は好ましく用いられる。 In addition, the amorphous niobium / tantalum-based oxide added to the inside of the reaction vessel has no difference between the solid solution and the mixture as long as the average composition for realizing the intended composition of the niobium / tantalate alkali type film is satisfied. From the viewpoint of controlling the raw material composition, a mixture of niobium oxide and tantalum oxide is preferably used.
　本発明において非晶質ニオブ／タンタル系酸化物の添加量は、水酸化アルカリと非晶質ニオブ／タンタル系酸化物とのモル比が、１：１．０×１０－４～１：１．０×１０５、さらには１：１．０×１０－２～１：１．０×１０４となる量であってよい。非晶質ニオブ／タンタル系酸化物の添加量が、この範囲の下限値より多い量であると溶液中に溶解したニオブ／タンタルが一定量存在できるので好ましく、この範囲の上限値より少ない量であると、溶解したニオブ／タンタルが均一核生成を起こさずに溶液中に存在するので好ましい。上記のモル比は、１：１.０×１０-3～１：１.0×１０５、さらには１：１.0×１０２～１：1.0×10５であってよい。 In the present invention, the addition amount of the amorphous niobium / tantalum oxide is such that the molar ratio of alkali hydroxide to the amorphous niobium / tantalum oxide is 1: 1.0 × 10 −4 to 1: 1. The amount may be 0 × 10 5 or even 1: 1.0 × 10 −2 to 1: 1.0 × 10 4 . If the addition amount of the amorphous niobium / tantalum oxide is larger than the lower limit value of this range, it is preferable because a certain amount of niobium / tantalum dissolved in the solution can be present, and the amount is smaller than the upper limit value of this range It is preferred that the dissolved niobium / tantalum be present in solution without homogeneous nucleation. The above molar ratio may be 1: 1.0 × 10 −3 to 1: 1.0 × 10 5 or even 1: 1.0 × 10 2 to 1: 1.0 × 10 5 .
　非晶質ニオブ／タンタル系酸化物は、粉末状であると、加熱及び加圧時のアルカリ水溶液への溶解性（アルカリ水溶液との反応性）が高いので好ましいが、塊状などその他の形状であってもよい。 Amorphous niobium / tantalum-based oxides are preferable because they are powdery, because they have high solubility (reactivity with alkaline aqueous solution) in alkaline aqueous solution when heated and pressurized, but they are other shapes such as bulk. May be
　非晶質ニオブ／タンタル系酸化物は、反応容器内に予め入れておき、その反応容器に水（又はアルカリ水溶液）を添加してもよいし、あるいは反応容器に水（又はアルカリ水溶液）を入れておき、それに非晶質ニオブ／タンタル系酸化物を添加してもよい。 The amorphous niobium / tantalum oxide may be previously contained in a reaction container, and water (or aqueous alkali solution) may be added to the reaction container, or water (or aqueous alkali solution) may be charged in the reaction container. Alternatively, an amorphous niobium / tantalum oxide may be added thereto.
　本発明の製造方法では、得られる膜は、式Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３（式中、Ａはアルカリ金属の１種または２種以上であり、２種以上のアルカリ金属の割合は任意であり、０≦ｘ≦１である。）で表されるニオブ／タンタル酸アルカリを含む結晶であるが、ＣａＯ、ＣｕＯ、ＭｎＯ２、Ｓｂ２Ｏ３、ＢａＯ、ＺｒＯ２、ＴｉＯ2等の酸化物を含むことができ、それによって圧電特性などの特性を改良することができる。これらの酸化物は、アルカリ水溶液中に添加することで、水熱合成後にニオブ／タンタル酸アルカリ系膜中に主に固溶体及び／又は混合物として取り込まれる。複合酸化物を形成していてもよい。これらの酸化物の添加量は、ニオブ／タンタル酸アルカリ系膜の特性を改良する量であれば、特に限定されず、酸化物の種類にもよるが、ニオブ／タンタル酸アルカリ系膜を基準にして、３０重量％以下でよく、例えば、１～２０重量％、１～１０重量％は好ましいが、２重量％以上あるいは０．０１～１重量％が好ましいときもある。これらの酸化物の添加量は、上記式で表されるニオブ／タンタル酸アルカリに固溶することが知られている量であることは好ましい。しかし、添加量が固溶限界内であっても、全部が固溶せず、混合物になってもよい。 In the production method of the present invention, the obtained film has the formula A (Nb 1-x Ta x ) O 3 (wherein A is one or two or more alkali metals, and the ratio of two or more alkali metals) Is a crystal containing an alkali of niobium / tantalate represented by 0 ≦ x ≦ 1), but CaO, CuO, MnO 2 , Sb 2 O 3 , BaO, ZrO 2 , TiO 2 etc. And oxides of the same can be included, thereby improving properties such as piezoelectric properties. These oxides are mainly incorporated as a solid solution and / or a mixture in the niobium / tantalate alkali type membrane after the hydrothermal synthesis by being added to the aqueous alkali solution. A composite oxide may be formed. The addition amount of these oxides is not particularly limited as long as it is an amount to improve the properties of the niobium / tantalate alkali based film, and although it depends on the kind of the oxide, it is based on the niobium / tantalate alkali based film. It may be 30 wt% or less, for example, 1 to 20 wt%, preferably 1 to 10 wt%, but sometimes 2 wt% or more or 0.01 to 1 wt%. The addition amount of these oxides is preferably an amount known to be dissolved in the niobium / tantalate alkali represented by the above formula. However, even if the addition amount is within the solid solution limit, all may not form a solid solution and may be a mixture.
　本発明の製造方法において、ニオブ／タンタル酸アルカリ系膜を堆積させる基体は、限定されないが、ペロブスカイト系の結晶構造を有する基体であることが好ましい。基体がペロブスカイト系の結晶構造を有すると、ニオブ／タンタル酸アルカリと結晶構造が同じであるので、ニオブ／タンタル酸アルカリ系膜が堆積しやすく、さらには一次配向膜やエピタキシャル膜を形成することもできるので好ましい。 In the manufacturing method of the present invention, the substrate on which the niobium / tantalate alkali based film is deposited is not limited, but is preferably a substrate having a perovskite crystal structure. If the substrate has a perovskite crystal structure, the crystal structure is the same as that of an alkali of niobium / tantalate, and therefore, it is easy to deposit a niobium / tantalate alkali film, and furthermore, it is possible to form a primary alignment film or an epitaxial film. It is preferable because it can be done.
　好ましく用いられるペロブスカイト系の結晶構造を有する基体としては、ペロブスカイト型酸化物を挙げることができ、ペロブスカイト型酸化物は、ＡＢＯ３（式中、ＡはＬｉ, Ｎａ, Ｋ, Ｒｂ, Ｍｇ, Ｃａ, Ｓｒ, Ｂａ, Ｐｂ, Ｂｉ, Ｌａ, Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ, Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕ, Ｙなどから選ばれ、Ｂは、Ｍｇ,Ｓｃ，Ｔｉ,Ｖ，Ｃｒ，Ｍｎ，Ｆｅ, Ｃｏ, Ｎｉ, Ｃｕ，Ｚｎ，Ｚｒ, Ｎｂ, Ｍｏ, Ｒｕ, Ｉｎ, Ｓｎ, Ｈｆ, Ｔａ, Ｗ, Ｉｒ, Ｐｂ, Ｂｉなどから選ばれる。Ａ，Ｂは複数であることができ、酸化物は固溶体を含む。）で表される酸化物であり、たとえば、ＢａＴｉＯ３, ＰｂＴｉＯ３, ＫＮｂＯ３、ＰｂＶＯ３などが挙げられる。 As a substrate having a perovskite crystal structure which is preferably used, a perovskite type oxide can be mentioned, and the perovskite type oxide is ABO 3 (wherein, A is Li, Na, K, Rb, Mg, Ca, It is selected from Sr, Ba, Pb, Bi, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, etc., and B is Mg, Sc, Ti And V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, In, Sn, Hf, Ta, W, Ir, Pb, Bi, etc. A and B are plural. And the oxide is an oxide represented by the solid solution), and examples thereof include BaTiO 3 , PbTiO 3 , KNbO 3 , PbVO 3 and the like.
　また、その他のペロブスカイト系の結晶構造を有する基体としては、Ｃｕ３Ａｕ構造、ＲｅＯ３構造、Ｋ２ＮｉＦ４構造、Ｓｒ３Ｔｉ２Ｏ７構造およびＳｒ４Ｔｉ３Ｏ１０構造、Ｂｉ４Ｔｉ３Ｏ１２構造、タングステンブロンズ構造を持つもの、あるいはＮａＣｌ構造、ダイヤモンド構造、閃亜鉛鉱構造、ＺｎＳ構造、高温型クリストバル石構造、ＣａＦ２構造、Ｃ-希土構造、Ｙ２Ｏ３構造を持つ基体などがある。 As other substrates having a perovskite crystal structure, Cu 3 Au structure, ReO 3 structure, K 2 NiF 4 structure, Sr 3 Ti 2 O 7 structure and Sr 4 Ti 3 O 10 structure, Bi 4 Ti 3 A substrate having an O 12 structure, a tungsten bronze structure, or a NaCl structure, a diamond structure, a zinc blende structure, a ZnS structure, a high temperature type cristobalite structure, a CaF 2 structure, a C-rare earth structure, a Y 2 O 3 structure and so on.
　さらに、本発明において用いる基体の結晶格子定数が生成すべきニオブ／タンタル酸アルカリ系膜の結晶格子定数と同じか近似するものであれば、格子整合性が高いので、好ましい。結晶格子定数がニオブ／タンタル酸アルカリの結晶格子定数との差は、１０％以下、さらには５％以下であることが好ましい。ニオブ酸アルカリの結晶格子定数は０．３８８～０．４０５ｎｍ程度、タンタル酸アルカリの結晶格子定数は０．３９５～０．４０５ｎｍ程度であるので、基体の結晶格子定数がそれぞれ０．３５０～０．４０５ｎｍ程度あるいは０．３８０～０．４５０ｎｍ程度、さらには０．３７０～０．４０５ｎｍ程度あるいは０．３８０～０．４２５ｎｍ程度である基体は好ましい。基体と、膜との格子整合性が高いと、一次配向膜、さらにはエピタキシャル膜を形成することができるので好ましい。また、基体と、膜との格子整合性が高いと、堆積できる膜厚が増加し、製膜速度を向上させる利点もある。 Furthermore, if the crystal lattice constant of the substrate used in the present invention is the same as or similar to the crystal lattice constant of the niobium / tantalate alkali based film to be produced, it is preferable because the lattice matching is high. The difference between the crystal lattice constant and the crystal lattice constant of niobium / alkali tantalate is preferably 10% or less, more preferably 5% or less. The crystal lattice constant of alkali niobate is about 0.388 to 0.405 nm, and the crystal lattice constant of alkali tantalate is about 0.395 to 0.405 nm. A substrate having a thickness of about 405 nm or about 0.380 to 0.450 nm, and further about 0.370 to 0.405 nm or about 0.380 to 0.425 nm is preferred. It is preferable that the lattice matching between the substrate and the film is high, because a primary alignment film and further an epitaxial film can be formed. In addition, when the lattice matching between the substrate and the film is high, the film thickness that can be deposited is increased, and there is also an advantage of improving the film forming speed.
　本発明において用いる基体は、導電性を示すものが好ましい。基体が導電性を示すと、ニオブ／タンタル酸アルカリ系膜が堆積しやすくなる。特に導電性を示すペロブスカイト系の結晶構造を有する基体が好ましく、例えば、Ｎｂ：ＳｒＴｉＯ３、Ｌａ：ＳｒＴｉＯ３などがある。本発明では、ニオブ／タンタル系酸化物を原料とすることで、ニオブ／タンタル酸アルカリ系膜の膜厚を顕著に増大できるが、さらに導電性を示すペロブスカイト系の結晶構造を有する基体（又はバッファ層）を用いることで製膜速度をより向上させることができるので、ニオブ／タンタル酸アルカリ系膜の厚膜化がより現実的なものにされる効果がある。 The substrate used in the present invention preferably exhibits conductivity. When the substrate exhibits conductivity, the niobium / tantalate alkali based film tends to be deposited. In particular, a substrate having a perovskite crystal structure exhibiting conductivity is preferable, and examples thereof include Nb: SrTiO 3 , La: SrTiO 3, and the like. In the present invention, by using a niobium / tantalum-based oxide as a raw material, the film thickness of the niobium / tantalate alkali-based film can be remarkably increased, but a substrate (or a buffer having a perovskite crystal structure showing conductivity) By using the layer), the film forming rate can be further improved, so that there is an effect that the thickening of the niobium / tantalate alkali type film can be made more realistic.
　また、導電性を示すものでなくても、格子定数や化学種が膜のそれに近いＫＴａＯ３などのペロブスカイト系の結晶構造を有する基体（又はバッファ層）を用いることで、ニオブ／タンタル酸アルカリ系膜の膜厚を増大でき、さらに製膜速度をより向上させることができる。格子定数や化学種が膜の格子定数や化学種に近い材料としては、例えば、ＫＴａＯ３などがある。基体をＫＴａＯ３にすると、同じペロブスカイト系の結晶構造を有するＬａＡｌＯ３,ＳｒＴｉＯ３などと比べて得られる膜厚が増大する。格子定数や化学種が膜の格子定数や化学種に近い基体と導電性を示す基体（バッファ層）を好ましく組み合わせることができる。 Furthermore, even if it does not exhibit conductivity, it is possible to use an alkali niobium / tantalate based system by using a substrate (or buffer layer) having a perovskite crystal structure such as KTaO 3 whose lattice constant or chemical species is close to that of the film. The film thickness of the film can be increased, and the film forming speed can be further improved. As a material having a lattice constant or chemical species close to that of the film, for example, there is KTaO 3 or the like. When the substrate is KTaO 3 , the film thickness obtained is increased compared to LaAlO 3 , SrTiO 3 or the like having the same perovskite crystal structure. It is possible to preferably combine a substrate (buffer layer) in which the lattice constant or chemical species is close to that of the film and the substrate exhibiting conductivity.
　本発明において用いる基体は、ペロブスカイト系の結晶構造を有する基体のほか、他のセラミックス、金属、プラスチックなどからなる基体でもよい。これらの基体を用いる場合には、基体表面にペロブスカイト系の結晶構造を有し、さらには導電性を有するバッファ層を含むことが好ましい。そのようなバッファ層としては、ＳｒＲｕＯ３、ＢａＳｒＲｕＯ３、ＬａＮｉＯ３、Ｌａ２ＮｉＯ５、ＬａＳｒＣｏＯ３などを挙げることができる。 The substrate used in the present invention may be a substrate made of other ceramics, metals, plastics or the like in addition to a substrate having a perovskite crystal structure. When these substrates are used, it is preferable to include a buffer layer having a perovskite crystal structure on the surface of the substrate and further having conductivity. As such a buffer layer, SrRuO 3 , BaSrRuO 3 , LaNiO 3 , La 2 NiO 5 , LaSrCoO 3 and the like can be mentioned.
　反応容器内の水（又はアルカリ水溶液）中に基体を浸漬させることは、上記したように、適当な保持手段を用いて行うことができる。本発明は水熱合成法であるので、膜を堆積させる基体の表面は水（又はアルカリ水溶液）中に浸漬させる必要がある。膜を堆積させたくない基体の表面は保護膜やマスク剤で覆ってもよい。 Immersion of the substrate in water (or aqueous alkali solution) in the reaction vessel can be carried out using an appropriate holding means as described above. Since the present invention is a hydrothermal synthesis method, the surface of the substrate on which the film is deposited needs to be immersed in water (or an aqueous alkaline solution). The surface of the substrate on which the film is not desired to be deposited may be covered with a protective film or a masking agent.
　また、基体表面をニオブ／タンタル酸アルカリが堆積しやすい領域と、堆積しにくい領域とで組合せれば、ニオブ／タンタル酸アルカリ系膜の選択成長が可能である。また、本発明では、水熱合成法であるから、基体の表面が平坦でなく、曲面であっても、ニオブ／タンタル酸アルカリ系膜を堆積させることが可能である。本発明では、基体の表面が平坦面のみならず曲面であっても、一軸配向又はエピタキシャル配向したニオブ／タンタル酸アルカリ系膜を堆積することができる。 In addition, if the substrate surface is combined with a region in which the niobium / tantalate is likely to be deposited and a region in which it is difficult to be deposited, selective growth of the niobium / tantalate alkali type film is possible. Further, in the present invention, since the hydrothermal synthesis method is used, it is possible to deposit a niobium / tantalate alkali type film even if the surface of the substrate is not flat and is a curved surface. In the present invention, a uniaxially oriented or epitaxially oriented alkali niobium / tantalate based film can be deposited even if the surface of the substrate is not only a flat surface but also a curved surface.
　反応容器内に、順番にかかわりなく、水（上記のように水含有溶媒であってよい。）と、その水中に溶解された水酸化アルカリと、水中に添加された非晶質ニオブ／タンタル系酸化物と、水中に浸漬された基体とを準備してから、反応容器を密封したのち、容器内を加熱することで、反応容器内は加圧されて、基体上にニオブ／タンタル酸アルカリ系膜が析出、堆積する。 Water (which may be a water-containing solvent as described above), alkali hydroxide dissolved in the water, and amorphous niobium / tantalum system added to the water, regardless of order in the reaction vessel After preparing the oxide and the substrate immersed in water, the reaction container is sealed, and then the inside of the reaction container is pressurized by heating the inside of the container, and the niobium / tantalate alkali system is formed on the substrate. The film is deposited and deposited.
　水酸化アルカリとニオブ／タンタル系酸化物との反応は、下記の反応式：
　２ＡＯＨ＋（Ｎｂ，Ｔａ）２Ｏ５⇒２Ａ（Ｎｂ，Ｔａ）Ｏ３＋Ｈ２Ｏ
（式中、Ａはアルカリ金属であり、１種または２種以上であることができる。）
で表される反応である。 The reaction of alkali hydroxide with niobium / tantalum oxide is represented by the following reaction formula:
2AOH + (Nb, Ta) 2 O 5 2 2A (Nb, Ta) O 3 + H 2 O
(In the formula, A is an alkali metal and can be one or more kinds.)
It is a reaction represented by
　ＡＮｂＯ３とＡＴａＯ３は、相互に全固溶体を形成することができるし、その類似する結晶構造と元素特性から圧電体特性においても両者は同様の特性を有することが知られている。そのため本発明の水熱合成反応においてＮｂとＴａは相互に置換可能な元素であり、同様に作用するものと考えられる。 It is known that ANbO 3 and ATaO 3 can mutually form a total solid solution, and from their similar crystal structure and elemental characteristics, both have similar characteristics in terms of piezoelectric characteristics. Therefore, Nb and Ta are mutually substitutable elements in the hydrothermal synthesis reaction of the present invention, and are considered to act similarly.
　Ａ（Ｎｂ，Ｔａ）Ｏ３は、基体表面に生成（堆積）するほか、反応容器内の水（アルカル水溶液）中に粉末としても生成する。実際には、殆どは（アルカル水溶液）中で粉末として生成し、基体表面に堆積する量は限られている。 A (Nb, Ta) O 3 is formed (deposited) on the surface of the substrate, and is also formed as a powder in water (alkali aqueous solution) in the reaction vessel. In practice, most of them are produced as powder in (alkali aqueous solution) and the amount deposited on the substrate surface is limited.
　本発明によれば、非晶質ニオブ／タンタル系酸化物を原料として用いると、意外なことに、結晶質ニオブ／タンタル系酸化物を用いる場合と比べて、堆積できる膜厚が顕著に増大し、析出効率も向上することが見出された。これは、従来技術における重要課題であったニオブ／タンタル酸アルカリ系配向膜の厚膜化におけるブレイクスルーを成すものであり、厚い膜厚のニオブ／タンタル酸アルカリ系配向膜を含む圧電又は焦電素子の実用化を現実的なものとする。 According to the present invention, when amorphous niobium / tantalum oxide is used as a raw material, surprisingly, the film thickness which can be deposited is remarkably increased as compared with the case of using crystalline niobium / tantalum oxide. It has been found that the deposition efficiency is also improved. This is a breakthrough in thickening of a niobium / tantalate alkali-based alignment film, which is an important issue in the prior art, and is a piezoelectric or pyroelectric including a thick niobium / tantalate alkali-based alignment film. The practical application of the element is made realistic.
　また、従来、結晶質のニオブ／タンタル系酸化物を原料として用いると、バッチ処理において基体上に堆積する膜の膜厚は数μｍ程度が限界であったが、本発明によって非晶質ニオブ／タンタル系酸化物を原料として用いると、意外なことに、基体上に堆積する膜の膜厚は明らかに増大した。本発明の製造方法によれば、１０μｍ以上、１２μｍ以上、１５μｍ以上、１７μｍ以上、さらには２０μｍ以上も可能である。この製膜できる膜厚の顕著な向上は、析出効率の向上との相乗効果で、膜厚が厚いニオブ／タンタル酸アルカリ系膜を含む圧電又は焦電素子及び機能性装置の実用化をさらに現実的なものにする。 Also, conventionally, when crystalline niobium / tantalum oxide is used as a raw material, the film thickness of the film deposited on the substrate in batch processing has been limited to about several μm, but according to the present invention amorphous niobium / Unexpectedly, the film thickness of the film deposited on the substrate is obviously increased when the tantalum-based oxide is used as a raw material. According to the manufacturing method of the present invention, 10 μm or more, 12 μm or more, 15 μm or more, 17 μm or more, or even 20 μm or more is possible. The remarkable improvement of the film thickness that can be formed into a film is a synergistic effect with the improvement of the deposition efficiency, and the practical realization of the piezoelectric or pyroelectric element and the functional device including the niobium / tantalate alkali type film having a large film thickness is further realized. Make it
　本発明の製造方法において、基体上に堆積する、消費されるニオブ／タンタル系酸化物の１モルを基準として４ミリモル以上、又は消費されるニオブ／タンタル系酸化物の０．５質量％以上であることができる。さらに、１０ミリモル以上又は１．２５質量％以上であることもできる。さらに、１００ミリモル質量％以上又は２０質量％以上であることもできる。 In the manufacturing method of the present invention, 4 mmol or more, or 0.5 mass% or more of the consumed niobium / tantalum oxide based on 1 mol of consumed niobium / tantalum oxide deposited on the substrate Can be. Furthermore, it may be 10 mmol or more or 1.25 mass% or more. Furthermore, it can be 100 millimole mass% or more or 20 mass% or more.
　基体上に堆積せず、粉末になったＡ（Ｎｂ，Ｔａ）Ｏ３は、例えば、ニオブ／タンタル系酸化物に再生するなど、再利用してもよい。 Powdered A (Nb, Ta) O 3, which is not deposited on the substrate, may be reused, for example, by being regenerated to a niobium / tantalum-based oxide.
　基体上に堆積するニオブ／タンタル酸アルカリ系膜は、一次配向膜、さらにはエピタキシャル膜であることができる。ある結晶基体の上に他の結晶膜が成長する場合に、結晶膜と結晶基体とで結晶の一つの結晶軸がほぼ合致して成長していることを一次配向膜、結晶の二つの結晶軸がほぼ合致して成長していることをエピタキシャル膜という。結晶粒ごとにエピタキシャル成長した”ローカルエピタキシャル成長“させた一軸配向膜や、エピタキシャル成長した結晶粒が実質的な大きさを有する単結晶のエピタキシャル膜も形成可能である。 The niobium / tantalate alkali based film deposited on the substrate can be a primary alignment film or an epitaxial film. When another crystal film is grown on a certain crystal base, it is observed that one crystal axis of the crystal grows almost in agreement with each other between the crystal film and the crystal base as two crystal axes of the primary alignment film and the crystal. It is called an epitaxial film that the growth is almost in agreement. It is also possible to form a "local epitaxial growth" uniaxially oriented film epitaxially grown for each crystal grain, or a single crystal epitaxial film in which the epitaxially grown crystal grains have a substantial size.
　反応の加熱温度は、限定するわけではないが、３００℃以下の低温であることができる。下限は室温（約３０℃）以上でよいが、一般的には５０～３００℃、さらには１００～２５０℃の範囲が好ましい。このように水熱合成法によれば、反応温度がニオブ／タンタル酸アルカリのキュリー温度より低くできるので、製膜後の冷却時に膜にクラックが入るなどの欠点がなく、より厚い良質の膜を得ることができる。 The heating temperature of the reaction can be, but is not limited to, a low temperature of 300 ° C. or less. The lower limit may be room temperature (about 30 ° C.) or higher, but generally, the range of 50 to 300 ° C., preferably 100 to 250 ° C. is preferable. Thus, according to the hydrothermal synthesis method, since the reaction temperature can be lower than the Curie temperature of the niobium / tantalate alkali, there is no defect that the film is cracked at the cooling after film formation, and a thicker high quality film can be obtained. You can get it.
　製膜温度を高くすると、水熱合成において生成物中の最も懸念される不純物である格子内ＯＨイオンの量を低減することができ、また、製膜温度によって格子内ＯＨ－の量を制御すること、圧電特性を調整することができる。 Higher deposition temperatures, the amount of the most concern The grating within OH ions as impurities in the product in the hydrothermal synthesis can be reduced, also, interstitial OH by deposition temperature - controlling the amount of The piezoelectric characteristics can be adjusted.
　本発明の製造方法によれば、製膜温度はニオブ／タンタル酸アルカリのキュリー温度より低いが、自己分極して、分極処理なしでも優れた圧電特性を示すニオブ／タンタル酸アルカリ系配向膜を得ることができる。 According to the manufacturing method of the present invention, although the film forming temperature is lower than the Curie temperature of the niobium / tantalate alkali, the niobium / tantalate alkali-based alignment film exhibiting self-polarization and excellent piezoelectric characteristics without polarization treatment is obtained. be able to.
　反応容器内の加熱は、オートクレーブによるほか、マイクロ波を照射して行ってもよい。マイクロ波加熱によれば、通常の加熱の時と比べて、顕著に製膜速度が向上する。例えば、反応装置として、マイクロ波加熱可能な反応装置（例えば、"flexiWAVE", Milestone General（登録商標））内に、耐アルカリ性、耐圧性の反応容器（テフロン／PEEKの二重容器)を設置して、反応容器内に入れた水にマイクロ波を照射し、光ファイバで容器内の温度を観測しながら、設定温度に加熱してよい。 The heating in the reaction vessel may be performed by microwave irradiation as well as by an autoclave. According to the microwave heating, the film forming speed is remarkably improved as compared with the normal heating. For example, as a reactor, an alkali-resistant pressure-resistant reaction container (Teflon / PEEK double container) is installed in a microwave-heatable reactor (for example, "flexiWAVE", Milestone General (registered trademark)). The water contained in the reaction vessel may be irradiated with microwaves and heated to the set temperature while observing the temperature in the vessel with an optical fiber.
　反応時の圧力は、密閉式反応容器を加熱することで、反応容器内部の圧力が上昇する圧力でよい。通常、５．０×１０４～３．５×１０６Ｐａ程度と考えられるが、限定されるものではない。 The pressure at the time of reaction may be a pressure at which the pressure inside the reaction vessel rises by heating the closed reaction vessel. Usually, it is considered to be about 5.0 × 10 4 to 3.5 × 10 6 Pa, but is not limited.
　このように、反応容器内の水中に水酸化アルカリと非晶質ニオブ／タンタル系酸化物と基体が存在する状態で、反応容器内を加熱すると、密閉式の反応容器内の圧力が上昇し、ニオブ／タンタル系酸化物が溶解して、不均一反応で基体表面にニオブ／タンタル酸アルカリ系膜が堆積する。 Thus, when the interior of the reaction vessel is heated in the presence of the alkali hydroxide and the amorphous niobium / tantalum oxide and the base in water in the reaction vessel, the pressure in the closed reaction vessel rises. The niobium / tantalum-based oxide dissolves and a niobium / tantalate alkali-based film is deposited on the surface of the substrate in an inhomogeneous reaction.
　反応時間は、原料が反応できる時間であればよく、限定されない。製造設備や原料組成にもよるが、一回のバッチ処理において、例えば、１～７２時間程度、さらに１．５～３６時間程度、特に１．５～２４時間程度でよい。本発明の製造方法における反応時間は、本発明を限定するわけではないが、最終膜厚が従来の結晶質原料を用いる場合より顕著に厚くなり、最終膜厚になるまでの時間は従来と比べて長くなる傾向がある。本発明の製造方法における製膜速度は、従来の結晶質ニオブ／タンタル系酸化物を用いる場合の製膜速度と同等であってよく、本発明は製膜速度によって限定されない。 The reaction time is not limited as long as the raw materials can react. Depending on the production equipment and the composition of the raw material, it may be, for example, about 1 to 72 hours, further about 1.5 to 36 hours, and particularly about 1.5 to 24 hours in one batch process. The reaction time in the production method of the present invention is not necessarily limited to the present invention, but the final film thickness is significantly thicker than in the case of using a conventional crystalline raw material, and the time until the final film thickness is Tend to be longer. The deposition rate in the production method of the present invention may be equal to the deposition rate in the case of using a conventional crystalline niobium / tantalum-based oxide, and the present invention is not limited by the deposition rate.
　本発明の製造方法によって作製されるニオブ／タンタル酸アルカリ系膜は、ペロブスカイト系の結晶構造を有し、一軸配向又はエピタキシャル配向しており、圧電体特性を示す。本発明によって作製されるニオブ／タンタル酸アルカリ系膜の圧電体特性は、従来の結晶質のニオブ／タンタル系酸化物を用いる水熱合成法で得られる膜の圧電体特性と比べて、相違がなく、同等であることが確認されている（実施例、図１４～１６などが参照される）。 The niobium / tantalate alkali-based film produced by the production method of the present invention has a perovskite-based crystal structure, is uniaxially oriented or epitaxially oriented, and exhibits piezoelectric characteristics. The piezoelectric characteristics of the niobium / tantalate alkali-based film produced according to the present invention are different from those of the film obtained by the hydrothermal synthesis method using the conventional crystalline niobium / tantalum-based oxide. It is confirmed that they are equivalent (refer to the example, FIGS. 14 to 16, etc.).
　本発明の製造方法によって作製されるニオブ／タンタル酸アルカリ系膜は、式Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３で表されるニオブ／タンタル酸アルカリの一軸配向又はエピタキシャル配向している配向膜であるが、ニオブ／タンタル酸アルカリの結晶は好ましく単一結晶であることができるが、異相を含んでもよい。 Niobium / tantalate alkaline film formed by the manufacturing method of the present invention has the formula A (Nb 1-x Ta x ) uniaxially oriented niobium / tantalum alkaline represented by O 3 or epitaxial orientation to that oriented film However, although the niobium / alkali tantalate crystals can preferably be single crystals, they may also contain heterophases.
　本発明の製造方法によれば、一回のバッチ処理で得られるニオブ／タンタル酸アルカリ系膜は、従来の結晶質のニオブ／タンタル系酸化物を用いた場合には膜厚は数μｍ程度が上限であったが、例えば１０μｍ以上、１２μｍ以上、１５μｍ以上も可能であり、さらには２０μｍ以上も可能であると考えられる。一回のバッチ処理が終了後にバッチ処理を複数回繰り返せば、より厚い膜厚のニオブ／タンタル酸アルカリ系膜を、膜質及び圧電体特性を損なうことなく得ることが可能であり、またそれによって圧電体特性に関しては膜厚が厚い分だけ向上も可能である。複数のバッチ処理により膜厚を、３０～６０μｍ、特に６０μm以上、７０μｍ以上、さらには１００μｍ以上、１５０μｍ以上、２００μｍ以上、１ｍｍ以上あるいは２ｍｍ以上のミリメートルオーダーにしてもよい。膜厚の上限は求める素子又は装置の特性に応じて決めればよいが、例えば、３ｍｍ以下、１ｍｍ以下、５００μｍ以下、３００μｍ以下などであってもよい。ニオブ／タンタル酸アルカリ系配向膜の膜厚を上記のように大きくでき、また結晶性に優れていると、従来の圧電又は焦電素子では実現できなかった圧電又は焦電特性を好ましく実現できる。 According to the manufacturing method of the present invention, the niobium / tantalate alkali-based film obtained by one batch processing has a film thickness of about several μm when using the conventional crystalline niobium / tantalum-based oxide. Although the upper limit is used, it is considered that, for example, 10 μm or more, 12 μm or more, 15 μm or more is possible, and further 20 μm or more is also possible. By repeating the batch process several times after the completion of one batch process, it is possible to obtain a thicker niobium / tantalate based film without impairing the film quality and the piezoelectric characteristics, and thereby piezoelectricity. With regard to the body characteristics, it is also possible to improve by the increase of the film thickness. The film thickness may be in the order of millimeters of 30 to 60 μm, particularly 60 μm or more, 70 μm or more, and further 100 μm or more, 150 μm or more, 200 μm or more, 1 mm or more, or 2 mm or more by batch processing. The upper limit of the film thickness may be determined according to the characteristics of the element or device to be obtained, but may be, for example, 3 mm or less, 1 mm or less, 500 μm or less, 300 μm or less, or the like. When the film thickness of the niobium / tantalate alkali type alignment film can be increased as described above and the crystallinity is excellent, the piezoelectric or pyroelectric characteristics which can not be realized by the conventional piezoelectric or pyroelectric element can be preferably realized.
　本発明の製造方法によって製膜したニオブ／タンタル酸アルカリ系配向膜は、配向性に優れ、しかも自己分極（分極処理なしでも分極方向が揃っている）していることができる。自己分極しているので、ポーリング分極処理なしでも、圧電素子として使用できる。なお、ニオブ／タンタル酸アルカリ系配向膜の配向性は堆積基体を選択することでも向上させることができる。 The niobium / tantalate alkali-based alignment film formed by the manufacturing method of the present invention is excellent in the orientation and can be self-polarized (the polarization direction is uniform even without the polarization treatment). Since it is self-polarizing, it can be used as a piezoelectric element without the poling treatment. The orientation of the niobium / tantalate alkali orientation film can also be improved by selecting the deposition substrate.
　得られたニオブ／タンタル酸アルカリ系膜は、ポストアニールすることができ、ポストアニールによれば結晶膜質が向上する。ポストアニールの温度は、例えば、１００～９００℃、１００～７５０℃、特に５００～７５０℃でよい。 The obtained niobium / tantalate alkali type film can be post-annealed, and the quality of crystalline film is improved by the post-annealing. The temperature of the post annealing may be, for example, 100 to 900 ° C., 100 to 750 ° C., in particular 500 to 750 ° C.
　高温でポストアニールして結晶膜質を向上させたニオブ／タンタル酸アルカリ系配向膜は、自己分極が消失するので、圧電又は焦電素子として使用するために分極処理を行ってよい。 The niobium / tantalate alkali type alignment film which has been post-annealed at high temperature to improve the crystal quality loses self-polarization, and thus may be subjected to polarization processing for use as a piezoelectric or pyroelectric element.
　本発明の第一の側面の製造方法によれば、一軸配向又はエピタキシャル配向した結晶を含むニオブ／タンタル酸アルカリ系膜及びこれを用いた圧電又は焦電素子や機能性装置が提供される。 According to the manufacturing method of the first aspect of the present invention, a niobium / tantalate alkali-based film containing a uniaxially or epitaxially oriented crystal and a piezoelectric or pyroelectric element or functional device using the same are provided.
　本発明によって得られるニオブ／タンタル酸アルカリ系膜は、各種の圧電素子などに応用される。代表的には、図２の圧電体素子１０の例に示すように、基体１１は下部電極１２を有し、その上にニオブ／タンタル酸アルカリ系膜１３、さらに上部電極１４を有するが、基体１１と下部電極１２との間には必要に応じてバッファ層１５を有してもよい。 The niobium / tantalate alkali type film obtained by the present invention is applied to various piezoelectric elements and the like. Typically, as shown in the example of the piezoelectric element 10 of FIG. 2, the base 11 has the lower electrode 12 and the niobium / tantalate alkali type film 13 and the upper electrode 14 thereon. A buffer layer 15 may be provided between the lower electrode 11 and the lower electrode 12 as needed.
　本発明の製造方法によって得られるニオブ／タンタル酸アルカリ系膜は、圧電体膜として、圧電アクチュエータ素子、圧力センサ、超音波振動子、振動発電デバイスなどに広く適用される。 The niobium / tantalate alkali type film obtained by the manufacturing method of the present invention is widely applied as a piezoelectric film to a piezoelectric actuator element, a pressure sensor, an ultrasonic vibrator, a vibration power generation device and the like.
　（配向膜、圧電素子、機能性装置）
　本発明の第二の側面によれば、式Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３（式中、Ａはアルカリ金属の１種または２種以上であり、２種以上のアルカリ金属の割合は任意であり、０≦ｘ≦１である。）で表され、一軸配向又はエピタキシャル配向した結晶を含むニオブ／タンタル酸アルカリ系膜であって、前記ニオブ／タンタル酸アルカリ系膜が、６０μm以上、好ましくは７０μm以上（ただし、式中のＡの９６モル％以上、特に１００％がＫの場合は１４０μm以上）の厚さを有するか及び／又は曲面を含む基体上に形成されていることを特徴とするニオブ／タンタル酸アルカリ系膜が提供される。 (Alignment film, piezoelectric element, functional device)
According to the second aspect of the present invention, the formula A (Nb 1-x Ta x ) O 3 (wherein A is one or two or more alkali metals, and the ratio of two or more alkali metals is And a niobium / tantalate alkali type film containing crystals uniaxially or epitaxially oriented, wherein the niobium / tantalate alkali type film is 60 μm or more. Preferably, it is formed on a substrate having a thickness of 70 μm or more (however, 96 mol% or more of A in the formula, particularly 140 μm or more when 100% is K) and / or including a curved surface An alkali niobium / tantalate based film is provided.
　本発明の第二の側面（以下、単に本発明ともいう。）において、ニオブ／タンタル酸アルカリ系膜の組成Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３及びその成分は、第一の側面で説明したと同様であってよい。 In the second aspect of the present invention (hereinafter, also simply referred to as the present invention), the composition A (Nb 1-x Ta x ) O 3 of the niobium / tantalate alkali type film and the components thereof are described in the first aspect. It may be the same as
　アルカリＡは、カリウム、ナトリウム、リチウム、ルビジウム、セシウム、フランシウム、バリウムから選ばれる１種又は２種以上であってよいが、カリウムとナトリウムの２種、又はカリウムとナトリウムとリチウムの３種であるか、これらを含むことが好ましい。カリウムまたはナトリウム単独と比較して、アルカリＡの含有種が２種、３種と増えることで圧電特性が向上することから、用途に合った圧電特性の設計が可能である。 The alkali A may be one or more selected from potassium, sodium, lithium, rubidium, cesium, francium and barium, but it is two types of potassium and sodium or three types of potassium and sodium and lithium. It is preferable to include these. Since the piezoelectric characteristics are improved by the increase in the content of alkali A contained to two or three as compared with potassium or sodium alone, the piezoelectric characteristics can be designed according to the application.
　アルカリがカリウムとナトリウムの２種を含む場合、x=K/(K+Na)は0～1であってよいが、特に0.4～0.6、さらには0.8～0.9あることが好ましい。 When the alkali contains two species of potassium and sodium, x = K / (K + Na) may be from 0 to 1, particularly preferably from 0.4 to 0.6, and more preferably from 0.8 to 0.9.
　アルカリがリチウムを含む場合、ｙ=Li/(K＋Na＋Li)が0～0.1、特に0～0.05であることが好ましい。 When the alkali contains lithium, y = Li / (K + Na + Li) is preferably 0 to 0.1, particularly 0 to 0.05.
　ニオブ／タンタル（Ｎｂ,Ｔａ）は、ニオブ又はタンタルの単独であるか、ニオブとタンタルの両方を含んでよい。ニオブ単独であることは好ましいが、ニオブとタンタルの両方を含み、０≦ｘ≦０．５、特に０．２≦ｘ≦０．３であってよい。ニオブとともにタンタルを含むことで圧電特性が向上することから、両方含んでいることが好ましい。 The niobium / tantalum (Nb, Ta) may be niobium or tantalum alone or may include both niobium and tantalum. Although niobium alone is preferred, it may contain both niobium and tantalum, and 0 ≦ x ≦ 0.5, in particular 0.2 ≦ x ≦ 0.3. It is preferable that both are included, since the piezoelectric properties are improved by including tantalum together with niobium.
　本発明の第二の側面のニオブ／タンタル酸アルカリ系膜は、一軸配向又はエピタキシャル配向した結晶を含む配向膜であり、６０μm以上、好ましくは７０μm以上（ただし、上記式中のＡ＝Ｋの場合、さらにはＡの９６モル％以上がカリウムである場合は、１１０μｍ以上、好ましくは１４０μｍ以上）の厚さを有するか及び／又は曲面を含む基体上に形成されていることを特徴とする。 The niobium / tantalate alkali type film according to the second aspect of the present invention is an oriented film containing crystals uniaxially or epitaxially oriented, and is 60 μm or more, preferably 70 μm or more (provided that A = K in the above formula) Furthermore, when 96 mol% or more of A is potassium, it is characterized in that it is formed on a substrate having a thickness of 110 μm or more, preferably 140 μm or more and / or including a curved surface.
　ある結晶基体の上に他の結晶膜が成長する場合に、結晶膜と結晶基体とで結晶の一つの結晶軸がほぼ合致して成長していることを一次配向膜、結晶の二つの結晶軸がほぼ合致して成長していることをエピタキシャル膜という。結晶粒ごとにエピタキシャル成長した”ローカルエピタキシャル成長“の一軸配向膜や、エピタキシャル成長した結晶粒が実質的な大きさを有する単結晶のエピタキシャル膜も形成可能である。基体上に成長した一軸配向又はエピタキシャル配向膜は、成長のために用いた基体から分離して一軸配向又はエピタキシャル配向膜単体とし、また分離した一軸配向又はエピタキシャル配向膜に他の膜や基体を接合したものであってもよい。ニオブ／タンタル酸アルカリ系膜が一軸配向膜又はエピタキシャル配向膜であることにより、優れた圧電特性を有することができる。 When another crystal film is grown on a certain crystal base, it is observed that one crystal axis of the crystal grows almost in agreement with each other between the crystal film and the crystal base as two crystal axes of the primary alignment film and the crystal. It is called an epitaxial film that the growth is almost in agreement. It is also possible to form a uniaxially oriented film "local epitaxial growth" epitaxially grown for each crystal grain, or an epitaxial film of a single crystal in which the epitaxially grown crystal grain has a substantial size. The uniaxially oriented or epitaxially oriented film grown on the substrate is separated from the substrate used for growth to form a uniaxially oriented or epitaxially oriented film alone, and another film or substrate is joined to the separated uniaxially oriented or epitaxially oriented film. It may be When the niobium / tantalate alkali type film is a uniaxial alignment film or an epitaxial alignment film, it can have excellent piezoelectric properties.
　本発明の第二の側面で提供されるニオブ／タンタル酸アルカリ系配向膜は、６０μm以上、好ましくは７０μm以上（ただし、上記式中のＡ＝Ｋの場合、さらにはＡの９６モル％以上がカリウムである場合は、１１０μｍ以上、好ましくは１４０μｍ以上）の厚さを有するか及び／又は曲面を含む基体上に形成されていることにより、従来にない圧電又は焦電素子及びそれを応用した機能性装置が提供されるものであり、非鉛系圧電又は焦電体の厚膜化においてブレイクスルーをなすものである。従来、非鉛系圧電体では、ニオブ／タンタル酸アルカリ系配向膜が注目されているが、ＣＶＤやスパッタなどの気相法、ゾルゲル法では、いずれも５００℃以上の高温成膜又はプロセス温度が必要であり、蒸気圧の高いＫやＮａが揮発して組成ずれが生ずるという問題がある。３００℃以下の温度で製膜できる水熱合成法では、従来、製膜速度が低いために、６０μm以上、好ましくは７０μm以上（上記式中のＡ＝Ｋの場合、さらにはＡの９６モル％以上がカリウムである場合は、１１０μｍ以上、好ましくは１４０μｍ以上）の厚膜化がされていなかった。本発明の第二の側面によって提供される膜厚６０μm以上、好ましくは７０μm以上（上記式中のＡ＝Ｋの場合、さらにはＡの９６モル％以上がカリウムである場合は、１１０μｍ以上、好ましくは１４０μｍ以上）のニオブ／タンタル酸アルカリ系配向膜は、上記の厚い膜厚と良好な配向性を有することで、従来にない２～１００Ｈｚの低周波の共振振動数を有することができ、また高い出力を有することができるので、従来のニオブ／タンタル酸アルカリ系配向膜を用いる圧電素子では実現できなかった新しい用途（機能性装置）を実現することができる。 The niobium / tantalate alkali-based alignment film provided in the second aspect of the present invention has a thickness of 60 μm or more, preferably 70 μm or more (however, when A = K in the above formula, 96 mol% or more of A is In the case of potassium, it has a thickness of 110 μm or more, preferably 140 μm or more) and / or is formed on a substrate including a curved surface, so that it is an unconventional piezoelectric or pyroelectric element and the function to which it is applied A sexing device is provided which makes a breakthrough in the thickening of lead-free piezoelectric or pyroelectric materials. Conventionally, in lead-free piezoelectric materials, niobium / tantalate alkali-based alignment films have attracted attention, but in vapor phase methods such as CVD and sputtering, and in sol-gel methods, high-temperature film formation or process temperatures of 500 ° C. or higher It is necessary, and there is a problem that K and Na with high vapor pressure volatilize to cause compositional deviation. In the hydrothermal synthesis method capable of forming a film at a temperature of 300 ° C. or less, the film forming speed is conventionally 60 μm or more, preferably 70 μm or more (in the above formula, A = K, further 96 mol% of A). When the above is potassium, the thickening of 110 μm or more, preferably 140 μm or more is not performed. The film thickness provided by the second aspect of the present invention is 60 μm or more, preferably 70 μm or more (when A = K in the above formula, furthermore, when 96 mol% or more of A is potassium, 110 μm or more, preferably (Almost 140 μm or more) can have an unprecedented low frequency resonance frequency of 2 to 100 Hz by having the above-mentioned thick film thickness and good orientation. Since it can have a high output, it is possible to realize a new application (functional device) which could not be realized by a piezoelectric element using a conventional niobium / tantalate alkali-based alignment film.
　また、ニオブ／タンタル酸アルカリ系配向膜が曲面を含む基体上に形成されていることによっても、従来のニオブ／タンタル酸アルカリ系配向膜を用いる圧電素子では実現できなかった、新しい用途（機能性装置）を実現することができる。 In addition, even if the niobium / tantalate alkali-based alignment film is formed on a substrate including a curved surface, a new application (functionality can not be realized with a piezoelectric element using a conventional niobium / tantalate alkali-based alignment film. Device) can be realized.
　このように、本発明の第二の側面により新しく提供される機能性装置としては、例えば、医療用超音波プローブ、超音波トランスミッタ、超音波センサ、焦電発電装置、振動発電装置、アクチュエータがある。これらの機能性装置は、膜厚６０μm以上、好ましくは７０μm以上（上記式中のＡ＝Ｋの場合、さらにはＡの９６モル％以上がカリウムである場合は、１１０μｍ以上、好ましくは１４０μｍ以上）又は曲面を有することにより、特に低周波の共振振動数あるいは高い圧電パワーを特徴とする従来にない機能性装置である。 Thus, functional devices newly provided by the second aspect of the present invention include, for example, medical ultrasonic probes, ultrasonic transmitters, ultrasonic sensors, pyroelectric generators, vibration generators, and actuators. . These functional devices have a film thickness of 60 μm or more, preferably 70 μm or more (when A = K in the above formula, furthermore, when 96 mol% or more of A is potassium, 110 μm or more, preferably 140 μm or more) Or by having a curved surface, it is an unconventional functional device characterized in particular by a low frequency resonance frequency or high piezoelectric power.
　超音波プローブは、超音波を送信し、反射してきた超音波を受信して画像や血流情報として表示する超音波検査装置における超音波の送受信を行う部品である。本発明のニオブ／タンタル酸アルカリ系配向膜は、従来のニオブ／タンタル酸アルカリ系配向膜と比べて膜厚が大きいので、１～１００ＭＨｚ、さらに２～１００ＭＨｚの低い周波帯の超音波を送受信できる特徴がある。 The ultrasonic probe is a component that transmits and receives ultrasonic waves, receives ultrasonic waves that are reflected, and displays the images and blood flow information as ultrasonic waves in an ultrasonic inspection apparatus. The niobium / tantalate alkali oriented film of the present invention can transmit and receive ultrasonic waves in a low frequency band of 1 to 100 MHz and further 2 to 100 MHz since the film thickness is larger than that of a conventional niobium / tantalate alkali oriented film. There is a feature.
　図３に模式的に超音波プローブ２０の例を示すが、超音波プローブ２０は、バッキング材２１、振動子（圧電素子）２２、音響整合器２３、音響レンズ２４を含む。バッキング材２１は、振動子の背面に設置されていて、後方への超音波の伝搬を吸収、余分な振動を抑制して超音波のパルス幅を短くする役目がある。振動子２２は、超音波の送受信を行う部品である。音響整合器２３は、振動子２２は生体と比べて音響インピーダンスが大きく、そのままでは超音波が反射してしまうため、振動子２２と生体の中間的な音響インピーダンスをもつ物質を間に入れて反射を最小限に抑える部材である。音響レンズ２４は、超音波ビームを集束させる役割があり、シリコンゴムが多く使われている。 Although an example of the ultrasonic probe 20 is schematically shown in FIG. 3, the ultrasonic probe 20 includes a backing material 21, a vibrator (piezoelectric element) 22, an acoustic matching unit 23, and an acoustic lens 24. The backing material 21 is disposed on the back surface of the vibrator, and serves to absorb the propagation of ultrasonic waves to the rear, suppress extra vibration, and shorten the pulse width of the ultrasonic waves. The transducer 22 is a component that transmits and receives ultrasonic waves. In the acoustic matching unit 23, the vibrator 22 has a large acoustic impedance as compared with the living body, and the ultrasonic wave is reflected as it is. Therefore, a material having an acoustic impedance intermediate between the vibrator 22 and the living body is inserted and reflected. Is a member that minimizes the The acoustic lens 24 has a role of focusing the ultrasonic beam, and silicone rubber is often used.
　医療用超音波プローブは、医療用途において、人体などの生体に、超音波を送信し、反射してきた超音波を受信して画像や血流情報として表示するのが医療用超音波診断装置であり、超音波の送受信を行う部分がプローブである。 The medical ultrasonic probe is a medical ultrasonic diagnostic device that transmits ultrasonic waves to a living body such as a human body and receives reflected ultrasonic waves and displays them as images or blood flow information in medical applications. The part that transmits and receives ultrasonic waves is a probe.
　従来の医療用超音波プローブは、腹部、心臓、血管、眼球など身体の深部の画像診断に用いられているが、皮膚がんの診断には使えない。本発明のニオブ／タンタル酸アルカリ系配向膜を、プローブ２０の振動子（圧電素子）２２に用いることで、共振振動周波数を２～１００ＭＨｚの低い周波数帯として、皮膚近傍（例えば、深度０～１０ｍｍ）の画像診断が可能にされる。 Conventional medical ultrasound probes are used for diagnostic imaging of deep parts of the body such as the abdomen, heart, blood vessels, and eyes, but can not be used for diagnosis of skin cancer. By using the niobium / tantalate alkali type alignment film of the present invention for the vibrator (piezoelectric element) 22 of the probe 20, the resonance vibration frequency is a low frequency band of 2 to 100 MHz, and the vicinity of the skin (for example, depth 0 to 10 mm) Image diagnosis is made possible.
　また、本発明のニオブ／タンタル酸アルカリ系配向膜は、膜厚が厚いので高出力の超音波を発生することができるので、例えば、内視鏡を血管内の狭窄部に挿通するための機械走査装置として利用でき、また高出力（２～１００ＭＨｚの共振周波数において振動速度１ｍ／ｓ以上の高振幅）の超音波を照射して血管内の血栓を破砕する超音波医療装置などにも利用できる。 In addition, since the niobium / tantalate alkali-based alignment film of the present invention has a large film thickness and can generate high-power ultrasonic waves, for example, a machine for inserting an endoscope into a constriction portion in a blood vessel It can be used as a scanning device, and it can also be used as an ultrasonic medical device that uses a high power (amplitude of 1 m / s or higher at a resonance frequency of 2 to 100 MHz) high amplitude ultrasonic waves to break thrombi in blood vessels. .
　超音波トランスミッタとは、電気信号を音響振動に変換し媒体に音波を放射する送波用電気音響変換器。多くの場合，受波用の変換器としても用いられ，音響振動を電気信号に変換する機能も有する。 An ultrasonic transmitter is an electroacoustic transducer for transmission that converts an electrical signal into acoustic vibration and emits a sound wave to a medium. In many cases, it is also used as a transducer for receiving waves, and also has the function of converting acoustic vibration into an electrical signal.
　超音波センサは、超音波を発射してから物体に反射して戻ってくる超音波を受信して、目的物を検知したり、戻ってくる迄の時間を測定して目的物までの距離測定をするセンサが超音波センサである。発信器としては、振動子（圧電素子）に信号電圧を加え、振動子の共振振動周波数の超音波をスピーカ（送波器）から空中に放射する。受信器としては、空中からの超音波の波動をマイクロホン（受波器）で受信して振動子が電気出力を発生させる。送波器と受波器を合わせて超音波トランジューサ（電気音響変換素子）という。電気音響変換素子は原理的には一つの素子が送波器にも受波器にも働くが、送波と受波では空気の振動振幅も大幅に異なり、しかもインピーダンスを変えたほうが効率がよいので、別個のトランジューサを利用するのが通常である。マイクロコンピュータを用いて、発信器と受信器を制御し、検知、距離測定を行う。本発明のニオブ／タンタル酸アルカリ系配向膜は、従来の水熱合成法によって製造されたニオブ／タンタル酸アルカリ系配向膜と比べて、高出力（数１０ｋＨｚの周波数帯において振動速度として１～３ｍ／ｓが見込まれる）であり、ＰＺＴより遙かに高い高振幅出力であるので、非鉛系圧電素子を用いた超音波センサとして有望である。このような超音波センサは、高出力であるので、自動車における障害物の検知、距離測定に有利に利用できる。 The ultrasonic sensor emits ultrasonic waves and then receives ultrasonic waves reflected back from the object, detects an object, measures the time of returning wrinkles, and measures the distance to the object The sensor that does this is an ultrasonic sensor. As a transmitter, a signal voltage is applied to a vibrator (piezoelectric element), and an ultrasonic wave at a resonant vibration frequency of the vibrator is radiated from the speaker (transmitter) into the air. As a receiver, the wave of the ultrasonic wave from the air is received by the microphone (receiver), and the transducer generates an electric output. A transmitter and a receiver are collectively called an ultrasonic transducer (electro-acoustic transducer). In principle, one element acts as both a transmitter and a receiver in the electroacoustic transducer, but the vibration amplitude of air is also significantly different between transmission and reception, and it is more efficient to change the impedance. So it is normal to use a separate transducer. A microcomputer is used to control the transmitter and receiver to perform detection and distance measurement. The niobium / tantalate alkali-based alignment film of the present invention has a high output (1 to 3 m as a vibration velocity in a frequency band of several tens of kHz) as compared to a niobium / tantalate alkali-based alignment film manufactured by a conventional hydrothermal synthesis method. / S is expected, and it has high amplitude output much higher than that of PZT, so it is promising as an ultrasonic sensor using a lead-free piezoelectric element. Such an ultrasonic sensor has high output and can be advantageously used for obstacle detection and distance measurement in a car.
　焦電発電装置とは、図４に模式的に示す焦電発電装置３０の例を参照すると、焦電素子３１は強誘電体３２を電極３３の間に挟持してなる。この焦電素子３１に時間変化する熱源３４が作用すると、温度変化に対応して強誘電体３２に変動する電圧が発生して発電が行われる。本発明のニオブ／タンタル酸アルカリ系配向膜は、従来の水熱合成法によって製造されたニオブ／タンタル酸アルカリ系配向膜と比べて、高い圧電特性を有することから、非鉛系圧電素子を用いた焦電発電装置として有望である。 Referring to the example of the pyroelectric power generation device 30 schematically shown in FIG. 4 as the pyroelectric power generation device, the pyroelectric element 31 is formed by sandwiching the ferroelectric substance 32 between the electrodes 33. When the heat source 34 that changes with time acts on the pyroelectric element 31, a voltage that fluctuates in the ferroelectric 32 is generated according to the temperature change, and power generation is performed. Since the niobium / tantalate based alkali oriented film of the present invention has higher piezoelectric properties as compared to the niobium / tantalate based alkali oriented film produced by the conventional hydrothermal synthesis method, a lead-free piezoelectric element is used. It is promising as a pyroelectric generator.
　振動発電装置とは、振動子（圧電素子）に機械的な外力、振動が加わることにより、振動子の振動を電力に変換して取り出す発電装置である。本発明のニオブ／タンタル酸アルカリ系配向膜は、従来の水熱合成法によって製造されたニオブ／タンタル酸アルカリ系配向膜と比べて、高出力（２００Ｈｚ以下の共振周波数において１．７μＷ・Ｇ－２ｍｍ－３の出力電力密度）であり、ＰＺＴにより近い出力であるので、非鉛系圧電素子を用いた振動発電装置として有望である。 A vibration power generation device is a power generation device which converts vibration of a vibrator into electric power and takes it out by applying mechanical external force and vibration to the vibrator (piezoelectric element). The niobium / tantalate alkali-based alignment film of the present invention has a high output (1.7 μW · G − at a resonance frequency of 200 Hz or less), as compared to a niobium / tantalate alkali-based alignment film manufactured by a conventional hydrothermal synthesis method. Since the output power density of 2 mm- 3 ) and the output close to that of PZT, it is promising as a vibration power generator using a lead-free piezoelectric element.
　アクチュエータとは、圧電素子に電圧を印加することにより圧電体自身を変位させ（逆圧電効果）、機械的な力を発生させる装置である。本発明のニオブ／タンタル酸アルカリ系配向膜は、従来の水熱合成法によって製造されたニオブ／タンタル酸アルカリ系配向膜と比べて、高い圧電特性を有することから、非鉛系圧電素子を用いたアクチュエータとして有望である。 The actuator is a device that displaces the piezoelectric body itself by applying a voltage to the piezoelectric element (inverse piezoelectric effect) to generate a mechanical force. Since the niobium / tantalate based alkali oriented film of the present invention has higher piezoelectric properties as compared to the niobium / tantalate based alkali oriented film produced by the conventional hydrothermal synthesis method, a lead-free piezoelectric element is used. It is promising as an actuator.
　以下に実施例を用いて本発明を説明するが、本発明はこれらの実施例に限定されるものではない。 EXAMPLES The present invention will be described using examples below, but the present invention is not limited to these examples.
　（実施例１：ａ-Nb2O5の作成、７mol/L）
　非晶質の酸化ニオブ（ａ-Nb2O5）を次の手順で調製した。白金るつぼ中の酸化ニオブNb2O5（関東化学株式会社から入手の試薬、結晶質：10g）と炭酸カリウムK2CO3(52g)の混合物を950℃に１時間加熱して融解させてから放冷して得られた白色ケーキを蒸留水（500ｍL）溶解させた。溶液をろ過して固形物を除去後に、硝酸HNO3(200ｍL)を脱イオン水H２O(200mL)に溶解した酸性水溶液を添加して、白色粉末を沈殿させた。沈殿物を濾別し、脱イオン水で洗浄し、50℃で乾燥した。得られたのは非晶質の酸化ニオブであり、水和していた（a-Nb2O5・nH2O）。図５に、得られた非晶質の酸化ニオブと、結晶質の酸化ニオブのX線回折チャートを示す。 (Example 1: Creating a-Nb 2 O 5, 7mol / L)
Amorphous niobium oxide (a-Nb 2 O 5 ) was prepared by the following procedure. A mixture of niobium oxide Nb 2 O 5 (reagent obtained from Kanto Chemical Co., crystalline substance: 10 g) and potassium carbonate K 2 CO 3 (52 g) in a platinum crucible is heated at 950 ° C. for 1 hour for melting. The white cake obtained by allowing to cool was dissolved in distilled water (500 mL). The solution was filtered to remove solids, and then an acidic aqueous solution of nitric acid HNO 3 (200 mL) dissolved in deionized water H 2 O (200 mL) was added to precipitate a white powder. The precipitate was filtered off, washed with deionized water and dried at 50 ° C. An amorphous niobium oxide was obtained and was hydrated (a-Nb 2 O 5 .nH 2 O). FIG. 5 shows X-ray diffraction charts of the obtained amorphous niobium oxide and crystalline niobium oxide.
　次に、調製した非晶質の酸化ニオブを用いて、下記のようにして水熱合成法で(K,Na)NbO３膜(KNN膜)を作製した。 Next, using the prepared amorphous niobium oxide, a (K, Na) NbO 3 film (KNN film) was produced by a hydrothermal synthesis method as follows.
　図１に示すような内部をテフロンコートした（登録商標）オートクレーブ（内容積70ｍＬ）に、脱イオン水を用いて用意した水酸化カリウム７mol/L、水酸化ナトリウム７mol/LをK:Na＝9:1の比で混合したアルカリ水溶液20mLと、作製した非晶質酸化ニオブ（a-Nb2O5）0.25gとを入れ、さらに蓋に懸垂された長さ7.5mm、幅5mm、厚み0.5mmのSrRuO3//SrTiO3基板（SrRuO3の厚さ50nm）がアルカリ水溶液に浸漬するようにして、オートクレーブの蓋を閉じ、オートクレーブを密閉した。 In an autoclave (internal volume 70 mL) internally coated with Teflon as shown in FIG. 1, potassium hydroxide 7 mol / L prepared using deionized water, sodium hydroxide 7 mol / L, K: Na = 9 20 mL of an aqueous alkaline solution mixed in a ratio of 1: 1 and 0.25 g of the prepared amorphous niobium oxide (a-Nb 2 O 5 ), and further suspended on a lid: length 7.5 mm, width 5 mm, thickness 0.5 mm The lid of the autoclave was closed and the autoclave was sealed in such a manner that the SrRuO 3 // SrTiO 3 substrate (SrRuO 3 thickness 50 nm) was immersed in the aqueous alkali solution.
　密閉したオートクレーブを240℃に6時間加熱して水熱合成反応を行った後、取り出した基板を脱イオン水で複数回洗浄し、150℃で乾燥して、膜厚約11μmの(K,Na)NbO3(KNN膜)を得た。 The sealed autoclave is heated to 240 ° C. for 6 hours to carry out a hydrothermal synthesis reaction, and then the taken out substrate is washed with deionized water several times and dried at 150 ° C. to give a film thickness of about 11 μm (K, Na ) NbO 3 (KNN film) was obtained.
　得られたKNN膜についてpanalytical社製Axios advanceで分析すると、K/(K+Na)=0.88であった。図６にKNN膜のＸ線回析チャートを示すが、ペロブスカイト構造の(K,Na)NbO３膜が得られていること、エピタキシャル膜であることが確認される。ただし、図６では、反応時間が短いKNN膜の膜厚が2μｍのときと（図６（ｃ）（ｄ））、膜厚がほぼ最大膜厚10μｍのとき（図６（ａ）（ｂ））のＸ線回析チャートを示す。なお、図６では、後記の比較例１の対応するKNN膜の膜厚が2μｍと最大膜厚5μｍのときのＸ線回析チャートも示しているが、得られるKNN膜の結晶に原料が非結晶か結晶かによって相違は認められない。 The obtained KNN film was analyzed by panalytical Axios advance and found to be K / (K + Na) = 0.88. An X-ray diffraction chart of the KNN film is shown in FIG. 6, and it is confirmed that a (K, Na) NbO 3 film having a perovskite structure is obtained and it is an epitaxial film. However, in FIG. 6, when the film thickness of the KNN film having a short reaction time is 2 μm (FIG. 6 (c) and (d)), and when the film thickness is almost maximum 10 μm (FIG. 6 (a) and (b) 1 shows an X-ray diffraction chart of. Although FIG. 6 also shows an X-ray diffraction chart when the film thickness of the corresponding KNN film of Comparative Example 1 described later is 2 μm and the maximum film thickness is 5 μm, no raw material is used for the crystals of the obtained KNN film. There is no difference between crystals and crystals.
　KNN膜の上記膜厚約11μmは、実施例１の条件において、反応時間を変えたときの最大膜厚である。図７（ａ）に反応時間と得られる膜厚との関係をグラフで示す。反応時間が６時間程度までは反応時間の増加とともに膜厚が増大しているが、その後約11μｍの最大膜厚に到達すると、その後は反応時間が増加しても膜厚は増加しなかった。 The film thickness of about 11 μm of the KNN film is the maximum film thickness when the reaction time is changed under the conditions of Example 1. The relationship between the reaction time and the obtained film thickness is shown by a graph in FIG. 7 (a). The film thickness increases with an increase in reaction time up to about 6 hours, but when the maximum film thickness of about 11 μm is reached thereafter, the film thickness does not increase even if the reaction time increases.
　図８（ｃ）（ｄ）及び図９（ｃ）（ｄ）に得られたKNN膜の平面及び縦断面のＳＥＭ写真を示す。図８（ｃ）（ｄ）の平面図は、膜厚が2μｍと10μｍで異なるときの平面写真であるが、膜厚の増加とともに結晶粒径が増大していることが認められる。 FIGS. 8 (c) and (d) and FIGS. 9 (c) and (d) show SEM photographs of a plane and a longitudinal cross section of the obtained KNN film. The plan views of FIGS. 8 (c) and 8 (d) are plan photographs when the film thickness is different between 2 μm and 10 μm, but it is recognized that the crystal grain size increases as the film thickness increases.
　また、上記の方法で製造した非晶質の酸化ニオブ（水和物）を200℃で仮焼して水和水を除去した非晶質の酸化ニオブ（非水和物；a-Nb2O5）について、Ｘ線回折で非水和物であることを確認した上で、上記と同様の手順でKNN膜を作製したが、結果は水和物の場合と同様であり、結果に相違は認められなかった。以下の実施例では、非晶質の酸化ニオブ（水和物）を用いたが、単に非晶質の酸化ニオブと記載する。 In addition, amorphous niobium oxide (non-hydrate; a-Nb 2 O obtained by calcining at 200 ° C. the amorphous niobium oxide (hydrate) produced by the above method to remove hydration water. 5 ) After confirming that it was non-hydrated by X-ray diffraction, a KNN film was prepared in the same procedure as above, but the results are the same as in the case of the hydrate, and the difference in the results is I was not able to admit. In the following examples, amorphous niobium oxide (hydrate) was used, but is simply described as amorphous niobium oxide.
　（実施例２：６mol/L）
　実施例１と同様にして、ただし、KNN膜の水熱合成における水酸化カリウム、水酸化ナトリウムの濃度を７mol/Lから６mol/Lに変更して、実施例２のKNN膜を作製した。最大膜厚が得られる反応時間は16時間であった。 (Example 2: 6 mol / L)
The KNN film of Example 2 was produced in the same manner as in Example 1, except that the concentration of potassium hydroxide and sodium hydroxide in the hydrothermal synthesis of the KNN film was changed from 7 mol / L to 6 mol / L. The reaction time for obtaining the maximum film thickness was 16 hours.
　得られたKNN膜は、実施例１と同様の組成を有するペロブスカイト構造の(K,Na)NbO３膜（K/(K+Na)=0.88）であり、最大膜厚は約17μｍであった。 The obtained KNN film was a (K, Na) NbO 3 film (K / (K + Na) = 0.88) of the perovskite structure having the same composition as in Example 1, and the maximum film thickness was about 17 μm. .
　図７（ａ）に、実施例２で得られたKNN膜についても、反応時間と膜厚との関係をグラフで示す。実施例２のKNN膜は実施例1と比べて膜厚の堆積速度は遅かったが、最大膜厚は反応時間約16時間で約17μｍに達し、それ以上は増大しなかった。 FIG. 7A also shows the relationship between the reaction time and the film thickness of the KNN film obtained in Example 2 as a graph. The deposition rate of the film thickness of the KNN film of Example 2 was slower than that of Example 1, but the maximum film thickness reached about 17 μm at a reaction time of about 16 hours, and did not increase further.
　図７（ａ）を参照すると、各アルカリ濃度６mol/Lにおいて、非晶質原料の場合に結晶質原料の場合と比べて、製膜時間が３倍長くなり、膜厚が３倍以上になっている。同じ膜厚を得るためのニオブ原料の量は、非晶質において結晶質より１／３以下である。 Referring to FIG. 7A, at each alkali concentration of 6 mol / L, the film forming time is 3 times longer and the film thickness is 3 times or more in the case of the amorphous material as compared with the case of the crystalline material. ing. The amount of the niobium raw material for obtaining the same film thickness is 1/3 or less than that of crystalline in amorphous.
　（実施例３：原料の量、析出効率）
　実施例２において、非晶質ニオブ原料を0.25gから0.10g及び0.05gに減らして同様にKNN膜を堆積した。得られたKNN膜の膜厚はいずれも約17μｍであった。したがって、非晶質原料を用いると、結晶質原料と比べてニオブ原料の使用効率を高くすることができる。 (Example 3: Amount of raw material, precipitation efficiency)
In Example 2, the amorphous niobium source was reduced from 0.25 g to 0.10 g and 0.05 g to deposit the KNN film as well. The film thickness of each of the obtained KNN films was about 17 μm. Therefore, the use of an amorphous material can increase the use efficiency of the niobium material as compared to a crystalline material.
　同一条件での基板の寸法15x15mmへの製膜においてKNN膜の堆積効率を計算すると、原料が結晶質0.25g、非晶質0.25g、非晶質0.05gのとき、それぞれ1.38％、4.04％、20.2％であった。析出効率は、結晶質原料に対して約２２倍に向上できている。 The deposition efficiency of the KNN film is calculated in the film forming to the dimension of 15 × 15 mm of the substrate under the same conditions, and when the raw materials are 0.25 g of crystalline material, 0.25 g of amorphous material and 0.05 g of amorphous material, 1.38% and 4.04%, respectively. It was 20.2%. The deposition efficiency can be improved about 22 times with respect to the crystalline raw material.
　（実施例４～７：χ=K/(K+Na)比）
　実施例１と同様にして、ただし、KNN膜の水熱合成におけるオートクレーブ内の水酸化カリウム７mol/L、水酸化ナトリウム７mol/Lとの混合比K:Naを、1：0、7：3、8：2、10：0として、χ=K/(K+Na)比が異なるKNN膜を作製した。反応時間は最大膜厚が確認されるまでの時間とした。 (Examples 4 to 7: χ = K / (K + Na) ratio)
In the same manner as in Example 1, however, the mixing ratio K: Na of 7 mol / L potassium hydroxide and 7 mol / L sodium hydroxide in the autoclave in the hydrothermal synthesis of the KNN membrane, 1: 0, 7: 3, KNN films different in χ = K / (K + Na) ratio were prepared as 8: 2 and 10: 0. The reaction time was the time until the maximum film thickness was confirmed.
　得られたKNN膜は、いずれも、実施例１と同様に、ペロブスカイト構造の(K,Na)NbO３膜であった。 The obtained KNN films were all (K, Na) NbO 3 films having a perovskite structure, as in Example 1.
　図１０に、実施例１及び実施例４～７で得られたKNN膜におけるχ=K/(K+Na)の比χを、原料における[KOH]/([KOH]+[NaOH])の比と対応させてグラフで示す。原料における[KOH]/([KOH]+[NaOH]) の比の増加とともに、KNN膜におけるχ=K/(K+Na)の比も増加するが、特に[KOH]/([KOH]+[NaOH])の比が約０．７～０．９の範囲でKNN膜におけるχ=K/(K+Na)の比が急激に増加している。 In FIG. 10, the specific χ of χ = K / (K + Na) in the KNN films obtained in Example 1 and Examples 4 to 7 is the difference between [KOH] / ([KOH] + [NaOH]) in the raw material. It shows in the graph corresponding to the ratio. As the ratio of [KOH] / ([KOH] + [NaOH]) in the raw material increases, the ratio of χ = K / (K + Na) in the KNN film also increases, but in particular [KOH] / ([KOH] + The ratio of χ = K / (K + Na) in the KNN film rapidly increases when the ratio of [NaOH]) is in the range of about 0.7 to 0.9.
　図１１に、実施例１及び実施例４～７で得られたKNN膜における最大膜厚を、原料における[KOH]/([KOH]+[NaOH]) の比と対応させてグラフで示す。図１１には、後述の比較例（結晶質酸化ニオブを原料とした場合）の対応する結果も示しているが、実施例では対応する比較例と比べて、すべての[KOH]/([KOH]+[NaOH])比において、最大膜厚が増大していることが認められる。また、[KOH]/([KOH]+[NaOH])比が約０．７～１．０、特に０．７５～１．０において最大膜厚も、従来例に対する膜厚の増加も、比較的に大きい。 FIG. 11 is a graph showing the maximum film thicknesses of the KNN films obtained in Example 1 and Examples 4 to 7, corresponding to the ratio of [KOH] / ([KOH] + [NaOH]) in the raw materials. Although the corresponding result of the below-mentioned comparative example (when crystalline niobium oxide is used as the raw material) is also shown in FIG. 11, all [KOH] / ([KOH] / ([KOH]) are compared in the example as compared with the corresponding comparative example. It can be observed that the maximum film thickness is increased at the ratio of [+ NaOH]. Also, when the [KOH] / ([KOH] + [NaOH]) ratio is about 0.7 to 1.0, in particular 0.75 to 1.0, the maximum film thickness is also compared to the increase in film thickness relative to the conventional example. It is big.
　（実施例８：７回堆積）
　実施例１と同様にして、添加する水酸化カリウムと水酸化ナトリウムの溶液を混合比K:Na=9:1とし、製膜時間を16時間に変更してKNN膜を堆積した。さらに、製膜後溶液および残留粉末を取り出し、上記と同じ条件で、新しい非晶質ニオブ原料および混合溶液をオートクレーブ内に添加して堆積を続ける操作を合計７回繰り返した。得られたKNN膜は0.13mmであった。 (Example 8: deposited seven times)
In the same manner as in Example 1, a KNN film was deposited by changing the film formation time to 16 hours with the solution of potassium hydroxide and sodium hydroxide to be added set at a mixing ratio of K: Na = 9: 1. Further, the solution after film formation and the residual powder were taken out, and under the same conditions as described above, new amorphous niobium raw material and mixed solution were added into the autoclave and deposition was continued a total of seven times. The obtained KNN film was 0.13 mm.
　また、非晶質ニオブ原料を結晶質原料に代える以外は同様にして７回KNN膜を堆積したところ、得られたKNN膜の膜厚は50μｍ未満であった。 Further, when the KNN film was deposited seven times in the same manner except that the amorphous niobium raw material was replaced with the crystalline raw material, the film thickness of the obtained KNN film was less than 50 μm.
　図１２に、得られたKNN膜のSEM断面写真を示す。（ａ）は非晶質ニオブ原料、（ｂ）は結晶質ニオブ原料で得られたKNN膜である。 The SEM cross-section photograph of the obtained KNN film | membrane is shown in FIG. (A) is an amorphous niobium raw material, and (b) is a KNN film obtained from a crystalline niobium raw material.
　（比較例１～２：実施例１～２の対照）
　実施例１～２と同様にして、ただし、KNN膜の水熱合成における原料酸化ニオブを非晶質酸化ニオブではなく、結晶質酸化ニオブを用いて、それぞれ比較例１～２のKNN膜を作製した。反応時間は最大膜厚が確認されるまでの時間とした。 (Comparative Examples 1 to 2: Controls of Examples 1 to 2)
In the same manner as in Examples 1 and 2, except that the raw material niobium oxide in the hydrothermal synthesis of the KNN film is not amorphous niobium oxide but crystalline niobium oxide, the KNN films of Comparative Examples 1 and 2 are prepared. did. The reaction time was the time until the maximum film thickness was confirmed.
　結晶質酸化ニオブは、市販の試薬（関東化学株式会社）であるが、図２のＸ線回折チャートに示されるように、Nb2O5結晶の特性ピークが認められる。 Although crystalline niobium oxide is a commercially available reagent (Kanto Chemical Co., Ltd.), characteristic peaks of Nb 2 O 5 crystals are observed as shown in the X-ray diffraction chart of FIG.
　得られたKNN膜は、実施例１～２のKNN膜と同様のペロブスカイト構造の(K,Na)NbO３膜であった。 The obtained KNN film was a (K, Na) NbO 3 film having a perovskite structure similar to that of the KNN films of Examples 1 and 2.
　しかし、得られたKNN膜の最大膜厚は、図７（ｂ）に示すように、比較例１及び２のいずれにおいても約5.5μｍで、殆ど差がなかった。 However, as shown in FIG. 7B, the maximum film thickness of the obtained KNN film was about 5.5 μm in both Comparative Examples 1 and 2, and there was almost no difference.
　図１３（ａ）（ｂ）に、図７（ａ）（ｂ）のチャートを原料が結晶質であるか非晶質であること以外は同じ条件である、実施例１と比較例１との対比（図１３（ａ））、実施例２と比較例２との対比（図１３（ｂ））を示す。図１３（ａ）（ｂ）から、同じ合成条件において、原料を結晶質から非晶質に変えることで、最大膜厚が顕著に増大することが認められる。 13 (a) and (b) show the charts of FIGS. 7 (a) and 7 (b) under the same conditions as in Example 1 and Comparative Example 1 except that the raw material is crystalline or amorphous. Comparison (FIG. 13 (a)) and comparison between Example 2 and Comparative Example 2 (FIG. 13 (b)) are shown. It can be seen from FIGS. 13 (a) and 13 (b) that the maximum film thickness is significantly increased by changing the raw material from crystalline to amorphous under the same synthesis conditions.
（比較例３～６：χ=K/(K+Na)比）
　比較例１と同様にして、ただし、KNN膜の水熱合成におけるオートクレーブ内の水酸化カリウム７mol/L、水酸化ナトリウム７mol/Lとの混合比K:Naを、1：0、7：3、8：2、10：0として、χ=K/(K+Na)比が異なるKNN膜を作製した。反応時間は最大膜厚が確認されるまでの時間とした。 (Comparative Example 3 to 6: χ = K / (K + Na) ratio)
In the same manner as Comparative Example 1, except that potassium hydroxide 7 mol / L and sodium hydroxide 7 mol / L in the autoclave in the hydrothermal synthesis of the KNN membrane were mixed at a ratio of K: Na of 1: 0, 7: 3, KNN films different in χ = K / (K + Na) ratio were prepared as 8: 2 and 10: 0. The reaction time was the time until the maximum film thickness was confirmed.
　得られたKNN膜は、いずれも、比較例１と同様に、ペロブスカイト構造の(K,Na)NbO３膜であった。 The obtained KNN films were all (K, Na) NbO 3 films having a perovskite structure, as in Comparative Example 1.
　図１０のKNN膜におけるχ=K/(K+Na)の比と原料における[KOH]/([KOH]+[NaOH])の比と対応させたグラフ、及び、図１１のKNN膜における最大膜厚と原料における[KOH]/([KOH]+[NaOH])の比と対応させたグラフに、実施例１、２、４～７と対応させて比較例１、２～６の結果も示す。 A graph corresponding to the ratio of χ = K / (K + Na) in the KNN film of FIG. 10 to the ratio of [KOH] / ([KOH] + [NaOH]) in the raw material, and the maximum in the KNN film of FIG. The graphs corresponding to the film thickness and the ratio of [KOH] / ([KOH] + [NaOH]) in the raw materials correspond to those of Examples 1, 2 and 4 to 7, and the results of Comparative Examples 1 to 2 are also shown. Show.
　本発明の実施例において、すべての原料組成において比較例と比べて、原料を結晶質から非晶質に変えることで、最大膜厚が増大することが認められる。 In the examples of the present invention, it is recognized that the maximum film thickness is increased by changing the raw material from crystalline to amorphous as compared with the comparative example in all the raw material compositions.
　（実施例９及び比較例７：圧電素子の作成、圧電特性）
　実施例１及び比較例１と同様にして、SrRuO3を製膜したSrTiO3基板上にペロブスカイト構造のKNN膜を堆積した後、管状炉を用いて600℃で１０分間アニールして得たKNN膜上に白金電極をスパッタで堆積して、KNN膜を上下電極で挟持した、実施例９及び比較例７の圧電素子を作製した。 (Example 9 and Comparative Example 7: Preparation of Piezoelectric Element, Piezoelectric Property)
In the same manner as in Example 1 and Comparative Example 1, a KNN film obtained by depositing a KNN film having a perovskite structure on an SrTiO 3 substrate on which SrRuO 3 is formed and annealing at 600 ° C. for 10 minutes using a tubular furnace Platinum electrodes were deposited thereon by sputtering, and the piezoelectric elements of Example 9 and Comparative Example 7 were produced, in which the KNN film was sandwiched between the upper and lower electrodes.
　ただし、実施例９及び比較例７の圧電素子におけるKNN膜の膜厚は、比較対象の膜厚を同等になるようにし、それぞれ2.0μｍと2.4μｍであった。 However, the film thicknesses of the KNN films in the piezoelectric elements of Example 9 and Comparative Example 7 were 2.0 μm and 2.4 μm, respectively, so as to make the film thickness of the comparison object equal.
　これらの圧電素子の圧電特性の測定には、セイコーインスツルメント社製原子間顕微鏡SPA400と強誘電体評価システムは株式会社東陽テクニカ社製のFCAを組み合わせた装置を用いた。圧電定数d33の測定における交流電圧の周波数は3.2Hzであった。 For measurement of the piezoelectric characteristics of these piezoelectric elements, an apparatus was used in which an atomic force microscope SPA400 manufactured by Seiko Instruments Inc. and an FCA manufactured by Toyo Corporation, Inc. were used as a ferroelectric evaluation system. The frequency of the AC voltage in the measurement of the piezoelectric constant d 33 was 3.2 Hz.
　実施例９及び比較例７の圧電素子において得られた比誘電率及び誘電損失、電圧分極ヒステリシス特性、電界誘起歪の結果を、それぞれ、図１４、図１５、図１６に示す。いずれも、実施例９と比較例７とにおいて、圧電特性は同等であることが示されている。 The results of the relative dielectric constant, dielectric loss, voltage polarization hysteresis characteristics, and electric field induced strain obtained in the piezoelectric elements of Example 9 and Comparative Example 7 are shown in FIG. 14, FIG. 15, and FIG. 16, respectively. The piezoelectric characteristics are shown to be equal between Example 9 and Comparative Example 7 in any case.
　（実施例１０：K/Na比と圧電（発電）特性の相関）
　実施例２と同様にして、ただし水酸化カリウムと水酸化ナトリウムの比率を変えてSrRuO3を製膜したSrTiO3基板上にペロブスカイト構造のKNN膜を堆積した。得られたKNN膜の堆積後(as depo.)膜と600℃熱処理後膜について、発電特性を測定した結果を図１７に示す。 (Example 10: Correlation between K / Na ratio and piezoelectric (power generation) characteristics)
In the same manner as in Example 2, a KNN film having a perovskite structure was deposited on an SrTiO 3 substrate on which SrRuO 3 was formed by changing the ratio of potassium hydroxide and sodium hydroxide. The power generation characteristics of the obtained KNN film after deposition (as depo.) And the film after heat treatment at 600 ° C. are shown in FIG.
　図１７によれば、発電特性の性能指標（FOM=(d33)2/(9εr））は、KNN膜のｘ＝K/(K+Na)比に依存して変化している。また、性能指数は（FOM=(d33)2/(9εr））は、ｘ＝0.88付近で最も高く、600℃熱処理後膜ではｘ＝0.2付近からｘ＝0.8付近まで広く高い値であるが、どちらの膜もx＝1.0では大きく低下している。 According to FIG. 17, the performance index (FOM = (d 33 ) 2 / (9ε r )) of the power generation characteristics changes depending on the x = K / (K + Na) ratio of the KNN film. In addition, the figure of merit (FOM = (d 33 ) 2 / (9ε r )) is the highest around x = 0.88, and the film after heat treatment at 600 ° C. has a wide high value from around x = 0.2 to around x = 0.8 However, both films are greatly reduced at x = 1.0.
　（実施例１１及び比較例８：圧電特性）
　実施例９及び比較例７と同様にして、実施例１１及び比較例８の圧電素子を作製した。ただし、実施例１１及び比較例８の圧電素子におけるKNN膜の膜厚は、それぞれ10μｍと5μｍのものを作製した。 Example 11 and Comparative Example 8 Piezoelectric Properties
Piezoelectric elements of Example 11 and Comparative Example 8 were produced in the same manner as in Example 9 and Comparative Example 7. However, the film thicknesses of the KNN films in the piezoelectric elements of Example 11 and Comparative Example 8 were 10 μm and 5 μm, respectively.
　実施例１１及び比較例８の各圧電素子について実施例９及び比較例７と同様にして、電圧分極ヒステリシス曲線性、電界誘起歪を測定し、結果を図１８（ａ）～（ｅ）及び図１９（ａ）～（ｅ）に示す。膜厚が変化（増大）しても、実施例の圧電素子の圧電特性は比較例の圧電特性と同等であることが示されている。 The voltage polarization hysteresis curve and the electric field induced strain were measured for each piezoelectric element of Example 11 and Comparative Example 8 in the same manner as in Example 9 and Comparative Example 7, and the results are shown in FIGS. 18 (a) to (e) and FIG. 19 (a) to (e). Even when the film thickness changes (increases), it is shown that the piezoelectric characteristics of the piezoelectric element of the example are equivalent to the piezoelectric characteristics of the comparative example.
　（実施例１２：アニール温度）
　実施例９と同様にして、実施例１２の圧電素子を作製した。ただし、実施例１２の圧電素子におけるKNN膜は、水熱合成後にアニールしないもの、アニール温度をそれぞれ500℃、600℃、700℃、750℃にしたものとした。これらの圧電素子の圧電特性を測定した結果を図２０に示す。 (Example 12: annealing temperature)
In the same manner as in Example 9, a piezoelectric element of Example 12 was produced. However, the KNN film in the piezoelectric element of Example 12 was one that was not annealed after hydrothermal synthesis, and the annealing temperatures were 500 ° C., 600 ° C., 700 ° C., and 750 ° C., respectively. The results of measuring the piezoelectric characteristics of these piezoelectric elements are shown in FIG.
　（実施例１３：アニール処理の前後の厚さ）
　実施例１と同様にして、SrRuO3を製膜したSrTiO3基板（SrRuO3//SrTiO3）上にペロブスカイト構造のKNN膜を堆積した後、管状炉を用いて200℃で10分間アニールしてKNN膜を得た。このKNN膜について、アニール処理の前後で厚さを測定して、未アニール処理では8～10μｍ程度であるが、アニール処理後では12μｍ程度の膜厚が得られた。 (Example 13: Thickness Before and After Annealing Treatment)
In the same manner as in Example 1, after depositing a KNN film having a perovskite structure on the SrTiO 3 substrate was formed a SrRuO 3 (SrRuO 3 // SrTiO 3 ), and annealed for 10 minutes at 200 ° C. using a tubular furnace The KNN membrane was obtained. The thickness of this KNN film was measured before and after the annealing treatment, and was about 8 to 10 μm in the non-annealing treatment, but a film thickness of about 12 μm was obtained after the annealing treatment.
　（実施例１４：低温製膜KNN膜）
　実施例１３と同様にして、ただし、製膜温度240℃を200℃、150℃に変えて、KNN膜を得た。いずれの温度においても、240℃におけると同様にペロブスカイト構造のエピタキシャルKNN膜が確認された。150℃の低温で非晶質原料を用いてKNN膜を製膜できた。図２１に、上記の温度で得られたKNN膜の膜厚を、原料として結晶質酸化ニオブを用いた場合と対比して示す。非晶質原料を用いると、いずれの製膜温度でも結晶質原料を用いるよりもKNN膜の膜厚が増大している。 (Example 14: Low temperature film forming KNN film)
In the same manner as in Example 13, a KNN film was obtained by changing the film formation temperature of 240 ° C. to 200 ° C. and 150 ° C., respectively. At any temperature, an epitaxial KNN film of the perovskite structure was confirmed as in the case of 240 ° C. The KNN film could be formed using an amorphous raw material at a low temperature of 150 ° C. FIG. 21 shows the film thickness of the KNN film obtained at the above temperature, in contrast to the case where crystalline niobium oxide is used as a raw material. When an amorphous material is used, the film thickness of the KNN film is larger than that of a crystalline material at any film forming temperature.
　（実施例１５及び比較例９：7mol/L圧電特性）
　実施例９と同様にして実施例１５の圧電素子を作製した。ただし、KNN膜は実施例２及び比較例２と同様の方法で作製した。 Example 15 and Comparative Example 9: 7 mol / L Piezoelectric Properties
A piezoelectric element of Example 15 was produced in the same manner as Example 9. However, the KNN film was produced by the same method as in Example 2 and Comparative Example 2.
　実施例１５及び比較例９でKNN膜の膜厚を同じにした圧電素子の圧電特性を実施例９に記載した方法で評価したが、両者に特性の実質的な相違は認められなかった。 The piezoelectric characteristics of the piezoelectric element having the same film thickness of the KNN film in Example 15 and Comparative Example 9 were evaluated by the method described in Example 9, but no substantial difference in the characteristics was observed between the two.
　（実施例１６及び比較例１０：KNT膜）
　実施例１と同様にして、ただし酸化ニオブに変えて酸化タンタルを用いて、実施例１６の(K,Na)TaO３(KNT膜)を作製した。即ち、非晶質Ta2O5の調製についても、非晶質Ta2O5を用いたKNT膜の作製についても、実施例１と同様にした。 (Example 16 and Comparative Example 10: KNT Film)
A (K, Na) TaO 3 (KNT film) of Example 16 was produced in the same manner as Example 1, except that tantalum oxide was used instead of niobium oxide. That is, the preparation of the amorphous Ta 2 O 5 and the preparation of the KNT film using the amorphous Ta 2 O 5 were the same as in Example 1.
　非晶質の酸化タンタル（ａ-Ta2O5）を次の手順で調製した。白金るつぼ中の酸化タンタルTa2O5（関東化学株式会社から入手の試薬、結晶質：10g）と炭酸カリウムK2CO3(156g)の混合物を950℃に１時間加熱して融解させてから放冷して得られた白色ケーキを蒸留水（500ｍL）溶解させた。溶液をろ過して固形物を除去後に、硝酸HNO3(200ｍL)を脱イオン水H２O(200mL)に溶解した酸性水溶液を添加して、白色粉末を沈殿させた。沈殿物を濾別し、脱イオン水で洗浄し、50℃で乾燥した。得られたのは非晶質の酸化タンタルであり、水和していた（a-Ta2O5・nH2O）。得られたた非晶質の酸化タンタル（水和物）を200℃で仮焼して水和水を除去した非晶質の酸化タンタル（非水和物；a-Ta2O5）を得た。Ｘ線回折で、非水和物であることを確認した。図２２（ｃ）（ｄ）は、得られた非晶質の酸化タンタルのＸ線回折チャート及びＳＥＭ写真を示し、図２２（ａ）（ｂ）は、対応する結晶質の酸化タンタルのＸ線回折チャート及びＳＥＭ写真を示す。 Amorphous tantalum oxide (a-Ta 2 O 5 ) was prepared by the following procedure. A mixture of tantalum oxide Ta 2 O 5 (reagent obtained from Kanto Chemical Co., crystalline substance: 10 g) and potassium carbonate K 2 CO 3 (156 g) in a platinum crucible is heated at 950 ° C. for 1 hour for melting. The white cake obtained by allowing to cool was dissolved in distilled water (500 mL). The solution was filtered to remove solids, and then an acidic aqueous solution of nitric acid HNO 3 (200 mL) dissolved in deionized water H 2 O (200 mL) was added to precipitate a white powder. The precipitate was filtered off, washed with deionized water and dried at 50 ° C. It was amorphous tantalum oxide which was obtained and was hydrated (a-Ta 2 O 5 · n H 2 O). The obtained amorphous tantalum oxide (hydrate) is calcined at 200 ° C. to remove water of hydration, thereby obtaining amorphous tantalum oxide (non-hydrate; a-Ta 2 O 5 ). The It was confirmed by X-ray diffraction that it was non-hydrate. 22 (c) and (d) show X-ray diffraction charts and SEM photographs of the obtained amorphous tantalum oxide, and FIGS. 22 (a) and (b) show X-rays of the corresponding crystalline tantalum oxide. The diffraction chart and the SEM photograph are shown.
　次に、調製した非晶質酸化タンタルを用い、実施例１における非晶質酸化ニオブ0.25gのモル数と同じになる量0.416gとして、実施例１と同様の手順で（アルカリ溶液濃度7mol/L、K:Na=9:1、水熱条件:240℃,6h）、実施例１６の(K,Na)TaO３膜(KNT膜)を作製した。 Next, using the prepared amorphous tantalum oxide, the same procedure as in Example 1 is carried out in the same procedure as in Example 1 (alkali solution concentration 7 mol /, using 0.416 g as the number of moles of amorphous niobium oxide 0.25 g in Example 1). L, K: Na = 9: 1, hydrothermal condition: 240 ° C., 6 h), (K, Na) TaO 3 film (KNT film) of Example 16 was produced.
　この実施例１６のKNT膜のχ=K/(K+Na)比は0.480であり、KNT膜の最大膜厚は約600nmであった。 The χ = K / (K + Na) ratio of the KNT film of this Example 16 was 0.480, and the maximum film thickness of the KNT film was about 600 nm.
　また、非晶質酸化タンタルに変えて市販の結晶質酸化タンタルを用いる以外は上記と同様にして、比較例１０の(K,Na)TaO３膜(KNT膜)を作製した。この比較例１０のKNT膜のχ=K/(K+Na)比は0.570であり、KNT膜の最大膜厚は約100nmであった。 Further, a (K, Na) TaO 3 film (KNT film) of Comparative Example 10 was produced in the same manner as described above except that commercially available crystalline tantalum oxide was used instead of amorphous tantalum oxide. The χ = K / (K + Na) ratio of the KNT film of Comparative Example 10 was 0.570, and the maximum film thickness of the KNT film was about 100 nm.
　（実施例１７：KTaO3基板）
　実施例１と同様であるが、ただし、基板としてLaAlO3, SrTiO3, KTaO3を用い、かつ原料a-Nb2O5の仕込み量を0.25gとして、KNN膜を製膜した。基板がLaAlO3, SrTiO3ではKNN膜がやっと製膜できる程度であったが、基板がKTaO3では実施例１に近い膜厚約7μｍのKNN膜を製膜できた。基板KTaO3について、原料仕込み量を0.25gから1g（４倍）にするとKNN膜の膜厚も約４倍の良好なエピタキシャル膜が得られた。 (Example 17: KTaO 3 substrate)
The KNN film was formed in the same manner as in Example 1 except that LaAlO 3 , SrTiO 3 , and KTaO 3 were used as the substrate, and the preparation amount of the raw material a-Nb 2 O 5 was 0.25 g. When the substrate was LaAlO 3 or SrTiO 3 , the KNN film could be formed at last, but when the substrate was KTaO 3 , a KNN film having a thickness of about 7 μm close to that of Example 1 could be formed. For substrate KTaO 3, film thickness by about 4 times the good epitaxial film of the KNN layer when the raw material charged amounts from 0.25g to 1 g (4-fold) was obtained.
　さらに、LaAlO3, SrTiO3, KTaO3の表面にバッファ層としてSrRuO3層を形成した基板を用いて（原料仕込み量0.25g）、KNN膜を製膜したところ、SrRuO3//SrTiO3、SrRuO3//KTaO3基板では実施例１と同様の膜厚（約11μｍ）が得られ、SrRuO3//LaAlO3基板では膜厚（約5μｍ）が得られた。 Furthermore, when a KNN film was formed using a substrate having a SrRuO 3 layer formed as a buffer layer on the surface of LaAlO 3 , SrTiO 3 , KTaO 3 (raw material preparation amount 0.25 g), SrRuO 3 // SrTiO 3 , SrRuO A film thickness (about 11 μm) similar to that of Example 1 was obtained for the 3 // KTaO 3 substrate, and a film thickness (about 5 μm) was obtained for the SrRuO 3 // LaAlO 3 substrate.
　（実施例１８及び比較例１１：インコネル基板）
　市販のインコネル（登録商標）金属基板の表面にスパッタ法でLaNiO3膜を50nm、次いでSrRuO3膜を50nm堆積したバッファ層（SrRuO3/LaNiO3）を有する金属基板を用いて、実施例１及び比較例１と同様の手順で、実施例１８及び比較例１１のKNN膜を作製した。 (Example 18 and Comparative Example 11: Inconel Substrate)
Example 1 and Example 1 using a metal substrate having a buffer layer (SrRuO 3 / LaNiO 3 ) on which a 50 nm LaNiO 3 film and a 50 nm SrRuO 3 film are deposited by sputtering on the surface of a commercially available Inconel (registered trademark) metal substrate. In the same manner as in Comparative Example 1, KNN films of Example 18 and Comparative Example 11 were produced.
　実施例１８及び比較例１１で得られたKNN膜は、膜厚がそれぞれ8.5μm及び4.6μmであった。図２３（ａ）に実施例１８及び比較例１１で得られたKNN膜のＸ線回析チャートを示す。実施例１８では、膜厚は比較例１１と比べて明らかに増加しているが、結晶性は比較例１１と同じある。 The KNN films obtained in Example 18 and Comparative Example 11 had film thicknesses of 8.5 μm and 4.6 μm, respectively. An X-ray diffraction chart of the KNN films obtained in Example 18 and Comparative Example 11 is shown in FIG. In Example 18, the film thickness is clearly increased as compared with Comparative Example 11, but the crystallinity is the same as in Comparative Example 11.
　図２３（ａ）によれば、KNN膜は、極めて僅かに{110}ピークが観察されるが、ほぼ完全な{100}配向の単相である。LaNiO3膜の{100}自己配向性に基づくものである。 According to FIG. 23 (a), the KNN film is a single phase with a nearly perfect {100} orientation although a very slight {110} peak is observed. It is based on {100} self-orientation of LaNiO 3 film.
　また、上記のKNN膜の堆積を４回繰り返して膜厚約30μｍのKNN膜を作製した。この膜の配向性を半値幅（FWHM)で評価すると、厚みの増加に伴って、半値幅（FWHM)が23°から14°に減少し、配向度が向上していることが確認された（配向度99.5％）。 Further, the deposition of the above-mentioned KNN film was repeated four times to produce a KNN film having a film thickness of about 30 μm. When the orientation of this film was evaluated by the half width (FWHM), it was confirmed that the half width (FWHM) decreased from 23 ° to 14 ° as the thickness increased, and the degree of orientation was improved ( Degree of orientation 99.5%).
　参考のために、図２３（ｂ）に実施例１及び比較例１で得られたKNN膜のＸ線回析チャートを示す。実施例１８及び比較例１１で得られた金属基板上に作製したKNN膜の結晶性は、実施例１及び比較例１で得られたSrRuO3//SrTiO3基板上のKNN膜と同様である（図２３（ａ）と図２３（ｂ）とのピークの違いは基板の差に基づくものである）。 For reference, FIG. 23 (b) shows X-ray diffraction charts of the KNN films obtained in Example 1 and Comparative Example 1. The crystallinity of the KNN films prepared on the metal substrates obtained in Example 18 and Comparative Example 11 is the same as the KNN film on the SrRuO 3 // SrTiO 3 substrate obtained in Example 1 and Comparative Example 1 (The difference between the peaks in FIG. 23 (a) and FIG. 23 (b) is based on the difference in the substrate).
　また、上記と同様にして製膜後に、500℃で熱処理したKNNT膜（A=K/(K+Na)=0.9、C=Nb/(Nb+Ta)=0.87）において、圧電定数ｄ33＝70pm/Vが観察された。Ta置換により圧電定数が向上した。 In the same manner as above, the piezoelectric constant d 33 = in the KNNT film (A = K / (K + Na) = 0.9, C = Nb / (Nb + Ta) = 0.87) heat-treated at 500 ° C. 70 pm / V was observed. The piezoelectric constant was improved by the Ta substitution.
　（実施例１９：Pt基板に{111}配向）
　インコネル（登録商標）金属基板の表面にスパッタ法でPt膜を約500nm、次いでSrRuO3膜を50nm堆積したバッファ層（SrRuO3/Pt）を有する金属基板を用いて、実施例１と同様の手順で、実施例１９のKNN膜を作製した。 (Example 19: {111} orientation on Pt substrate)
Procedure similar to Example 1 using a metal substrate having a buffer layer (SrRuO 3 / Pt) on which a Pt film of about 500 nm and a SrRuO 3 film of about 50 nm are deposited by sputtering on the surface of Inconel® metal substrate. Thus, the KNN film of Example 19 was produced.
　得られたKNN膜のX線回析結果を図２４に示す。KNN膜が{111}配向していることが観測される。Pt膜が{111}自己配向性を有している結果であるが、Pt膜及びSrRuO3が{111}配向していることは別途確認されている。 The X-ray diffraction result of the obtained KNN film is shown in FIG. It is observed that the KNN film is {111} oriented. It is a result that the Pt film has {111} self-orientation, but it has been separately confirmed that the Pt film and SrRuO 3 are {111} oriented.
　（実施例２０：KNNT膜）
　実施例１６と同様にして、ただし、粉末原料として酸化ニオブ（ａ-Nb2O5）及び酸化タンタル（ａ-Ta2O5）を用いて、KOH:NaOH=9:1で一定とし、Nb/Taの組成比を0～1.0と連続的に変化させて、(K,Na)(Nb,Ta)O3膜（以下KNNT膜ともいう。）を作製した。得られたKNNT膜はエピタキシャル配向結晶膜である。 (Example 20: KNNT membrane)
In the same manner as in Example 16, but using niobium oxide (a-Nb 2 O 5 ) and tantalum oxide (a-Ta 2 O 5 ) as powder materials, KOH: NaOH = 9: 1, Nb constant, Nb The (K, Na) (Nb, Ta) O 3 film (hereinafter also referred to as a KNNT film) was manufactured by continuously changing the composition ratio of / Ta to 0 to 1.0. The obtained KNNT film is an epitaxial oriented crystal film.
　仕込み組成比Ｃ＝Nb2O5/（Nb2O5+Ta2O5）、仕込み組成比A=[KOH]/([KOH]+[NaOH]=0.9に対して、得られたKNNT配向膜のNb/(Nb+Ta)比及びK/(K+Na)比を、図２５に示す。Nb/(Nb+Ta)比は0.68から1.0まで連続的に変化し、K/(K+Na)比は0.83から0.92まで連続的に変化している。 The prepared KNNT orientation with respect to the feed composition ratio C = Nb 2 O 5 / (Nb 2 O 5 + Ta 2 O 5 ) and the feed composition ratio A = [KOH] / ([KOH] + [NaOH] = 0.9 The Nb / (Nb + Ta) ratio and the K / (K + Na) ratio of the film are shown in Figure 25. The Nb / (Nb + Ta) ratio varies continuously from 0.68 to 1.0, K / (K +) The Na) ratio changes continuously from 0.83 to 0.92.
　（実施例２１：KNLN膜）
　実施例１と同様にして、ただし、基体として(100)La:SrTiO3、粉末原料として（ａ-Nb2O5）、アルカリとして水酸化カリウム、水酸化ナトリウム及び水酸化リチウムを用いて、240℃で、(K,Na,Li)NbO3膜（以下、KNLN膜ともいう。）を作製し、エピタキシャル配向結晶膜が得られることを確認した。 (Example 21: KNLN film)
In the same manner as in Example 1, but using (100) La: SrTiO 3 as a substrate, (a-Nb 2 O 5 ) as a powder raw material, and potassium hydroxide, sodium hydroxide and lithium hydroxide as an alkali, 240 A (K, Na, Li) NbO 3 film (hereinafter also referred to as a KNLN film) was produced at ° C., and it was confirmed that an epitaxially oriented crystal film was obtained.
　仕込み比[KOH]/([KOH]+[NaOH])は0.9で一定とし、Liの仕込み比A=[LiOH]/([KOH]+[NaOH]+[LiOH])を0.00、0.01、0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10と連続的に変化させて、得られたKNLN膜をX線回折分析した。KNLN膜はすべての組成でエピタキシャル膜であるが、Aが0.05以上になるとK、Na、Li、Nb、Oから成る異相ピークが観察された。また、面外格子間隔がA=0.04近傍から変化しているので、結晶構造が変化している可能性がある。SEM観察によれば、異相は四角錘及び三角柱の形状であった。 The charge ratio [KOH] / ([KOH] + [NaOH]) is constant at 0.9, and the charge ratio of Li A = [LiOH] / ([KOH] + [NaOH] + [LiOH]) is 0.00, 0.01, 0.02. The obtained KNLN film was analyzed by X-ray diffraction analysis while changing continuously, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10. The KNLN film is an epitaxial film at all compositions, but when A is 0.05 or more, heterophase peaks consisting of K, Na, Li, Nb, and O were observed. In addition, since the out-of-plane lattice spacing changes from around A = 0.04, there is a possibility that the crystal structure is changing. According to SEM observation, the heterophases were in the shape of square pyramid and triangular prism.
　全ての仕込み比Aで製造された膜は緻密であるが、Aの増加に伴い膜厚は減少した。 The films produced at all feed ratios A were dense, but the film thickness decreased with the increase of A.
　仕込み比Aの増加（A=0からA＝0.04）に伴い誘電率は350から200に低下する傾向があるが、誘電損失は広い範囲で0.3以下であった。 The dielectric constant tends to decrease from 350 to 200 as the feed ratio A increases (A = 0 to A = 0.04), but the dielectric loss is 0.3 or less in a wide range.
　膜厚が10μｍであるとき、A=0.01近傍で強誘電性は最大となり、その自発分極値Prは約35μC/cm2を示した。 When the film thickness is 10 μm, the ferroelectricity is maximum around A = 0.01, and its spontaneous polarization value Pr is about 35 μC / cm 2 .
　（実施例２２：KNLNT膜）
　実施例２０及び２１と同様にして、ただし、基板として(100)La:SrTiO3、粉末原料として（ａ-Nb2O5）及び酸化タンタル（ａ-Ta2O5）(仕込み組成比Ｃ＝Nb2O5/（Nb2O5+Ta2O5）＝0.8)、アルカリとして水酸化カリウム、水酸化ナトリウム及び水酸化リチウム（仕込み組成比[KOH]/([KOH]+[NaOH])＝0.9、A=[LiOH]/([KOH]+[NaOH]+[LiOH]=0.01)を用いて、240℃で、(K,Na,Li)(Nb,Ta)O3膜（以下、KNLNT膜ともいう。）を作製し、エピタキシャル配向結晶膜が得られることを確認した。 (Example 22: KNLNT membrane)
In the same manner as in Examples 20 and 21, however, (100) La: SrTiO 3 as a substrate, (a-Nb 2 O 5 ) as a powder raw material, and tantalum oxide (a-Ta 2 O 5 ) (feed composition ratio C = Nb 2 O 5 / (Nb 2 O 5 + Ta 2 O 5 ) = 0.8), potassium hydroxide as alkali, sodium hydroxide and lithium hydroxide (feed composition ratio [KOH] / ([KOH] + [NaOH]) (K, Na, Li) (Nb, Ta) O 3 film (below, at 240 ° C. using A = [LiOH] / ([KOH] + [NaOH] + [LiOH] = 0.01); (Also referred to as KNLNT film), and it was confirmed that an epitaxially oriented crystal film could be obtained.
　得られたKNLNT膜（K/Na=0.9, Li/(K+Na+Li)=0.01,Nb/Ta=0.8）の圧電特性を図２６に示す。圧電特性ｄ３３は121pm/Vであった。 The piezoelectric properties of the obtained KNLNT film (K / Na = 0.9, Li / (K + Na + Li) = 0.01, Nb / Ta = 0.8) are shown in FIG. The piezoelectric characteristic d 33 was 121 pm / V.
　（実施例２３：自己分極）
　実施例１と同様にして、実施例２３のKNN膜を製膜した。得られたKNN膜を用いて実施例１１と同様に圧電素子（膜厚10μｍ）を作製し、圧電特性を評価した。圧電特性として、P-Eヒステリシス曲線の測定と、分極処理電界に対する圧電定数、e31,fを評価した。後者は、分極処理として測定周波数１ｋHz、測定電圧５Ｖp-pのパルス電圧を印加して、e31,fを測定した。 (Example 23: self polarization)
The KNN film of Example 23 was formed in the same manner as in Example 1. A piezoelectric element (film thickness 10 μm) was produced in the same manner as in Example 11 using the obtained KNN film, and the piezoelectric characteristics were evaluated. As the piezoelectric characteristics, measurement of the PE hysteresis curve, and the piezoelectric constant e31 , f with respect to the polarization processing electric field were evaluated. In the latter case, a pulse voltage at a measurement frequency of 1 kHz and a measurement voltage of 5 Vp-p was applied as polarization treatment to measure e 31, f .
　また、得られたKNN膜を酸素含有気流中600℃で10分間熱処理した。図２７に、as depo.のKNN膜と600℃で熱処理したKNN膜を用いて作製した圧電素子について測定したP-Eヒステリシス曲線と、分極処理電界に対するe31,fを示す。図２７の上図に見られるように、as depo.のKNN膜はP-Eヒステリシス曲線が大きくマイナスの電界側にシフトしていて（図２７上左図）、ポーリング電界による分極処理なしで、またポーリング電界に依存しない圧電特性（e31,f）を示すことから（図２７上右図）、自己分極していることが確認される。なお、as depo.のKNN膜における自己分極は膜厚が約２μｍから２２μｍまで観測され、e31,fの値の膜厚依存性はほぼ無かった。 Further, the obtained KNN film was heat-treated at 600 ° C. for 10 minutes in an oxygen-containing gas flow. FIG. 27 shows a PE hysteresis curve measured for a piezoelectric element manufactured using a KNN film of as depo. And a KNN film heat-treated at 600 ° C. and e 31, f with respect to a polarization-treated electric field. As seen in the upper drawing of FIG. 27, the KNN film of as depo. Has a large PE hysteresis curve shifted to the negative electric field side (upper drawing in FIG. 27), and without poling treatment by the poling electric field, poling From the fact that the piezoelectric characteristics (e 31, f ) that do not depend on the electric field are shown (upper diagram in FIG. 27), it is confirmed that self-polarization is performed. The self polarization in the as-depo KNN film was observed from about 2 μm to 22 μm, and there was almost no film thickness dependency of the values of e 31 and f .
　図２８に、as depo.のKNN膜と600℃で熱処理したKNN膜を用いて作製した圧電素子について測定した強誘電特性e31,f を示す。（ａ）は膜厚2.8μｍのas depo.KNN膜、（ｂ）は膜厚2.５μｍの600℃熱処理KNN膜、（ｃ）は（ａ）と（ｂ）の特性の比較、（ｄ）は強誘電特性の値である。 FIG. 28 shows ferroelectric characteristics e 31, f measured on a piezoelectric element manufactured using the KNN film of as depo. And the KNN film heat-treated at 600 ° C. (A) is a 2.8 μm thick as depo. KNN film, (b) is a 2.5 μm thick 600 ° C. heat-treated KNN film, (c) is a comparison of the characteristics of (a) and (b), (d) Is the value of the ferroelectric property.
　図２９に、as depo.のKNN膜を用いて作製した圧電素子について測定したe31,fの膜厚依存性を評価した結果を示す。図２９によれば、e31,fは膜厚に依存していない。 The result of having evaluated the film thickness dependence of e31 , f measured about the piezoelectric element produced using FIG. 29 using the KNN film | membrane of as depo. Is shown. According to FIG. 29, e 31, f do not depend on the film thickness.
　図３０に、as depo.のKNN膜と600℃で熱処理したKNN膜を用いて作製した圧電素子について測定したAFM(ｄ33)を示す。熱処理（アニール）することで、KNN膜の圧電特性が向上している。図３０において、白抜き四角形（□）は（K0.5Na0.5)NbO3について文献で報告されているAFM(ｄ33)の値であり、実施例２３で得られたKNN膜は、as depo.のKNN膜でも既報の値と匹敵する値であり、熱処理すると既報の値と比べて優れた値である。 FIG. 30 shows AFM (d 33 ) measured for a piezoelectric element manufactured using the KNN film as as depo. And the KNN film heat-treated at 600 ° C. The heat treatment (annealing) improves the piezoelectric characteristics of the KNN film. In FIG. 30, the open squares (□) are the values of AFM (d 33 ) reported in the literature for (K 0.5 Na 0.5 ) NbO 3 , and the KNN film obtained in Example 23 is as in the case of as depo. The KNN film also has a value comparable to the previously reported value, and the heat treatment is superior to the previously reported value.
　一方、図２７の下図に見られるように、600℃で熱処理したKNN膜はP-Eヒステリシス曲線にシフトがなく（図２７下左図）、また分極電圧に依存するe31,fから（図２７下右図）、自己分極がないこと、圧電特性には分極処理が必要であることが確認される。 On the other hand, as seen in the lower part of FIG. 27, the KNN film heat-treated at 600 ° C. has no shift in the PE hysteresis curve (FIG. 27 lower left) and from e 31, f depending on polarization voltage (FIG. 27 lower). Right), it is confirmed that there is no self-polarization and that the piezoelectric characteristics require polarization treatment.
　また、as depo.膜と600℃熱処理膜の圧電素子（膜厚10μｍ）を用いて、e31,fについて特性評価をした結果、自己分極したas depo.膜は従来知られている熱処理膜とほぼ同じ値であることが確認された。 In addition, as a result of evaluating the characteristics of e 31, f using the piezoelectric elements (film thickness 10 μm) of the as depo. Film and the 600 ° C. heat-treated film, the self-polarized as depo. It was confirmed that the values were almost the same.
　図３１の上方のグラフに、熱処理温度を変えたときのP-Eヒステリシス曲線のシフト量の変化を示す。as depo.のKNN膜から熱処理温度が上昇するに従い、シフト量が減少している。 The upper graph in FIG. 31 shows the change in shift amount of the PE hysteresis curve when the heat treatment temperature is changed. As the heat treatment temperature increases from the as depo. KNN film, the shift amount decreases.
　また、as depo.膜を真空中で加熱して、加熱温度と膜中から放出されるOH量を測定したところ、100℃以下からOH放出が始まり、200℃前後に低いOH放出ピークがあり、500℃付近で大きなOH放出ピークが観察された。化学吸着しているOHの放出は200℃前後にピークがあり、結晶内に取り込まれているOHの放出は500℃付近にピークがある。 Further, when the as depo. Film was heated in vacuum and the heating temperature and the amount of OH released from the film were measured, OH release started from 100 ° C. or less, and there was a low OH release peak around 200 ° C. A large OH emission peak was observed around 500 ° C. The release of chemisorbed OH has a peak at around 200 ° C., and the release of OH incorporated in the crystal has a peak at around 500 ° C.
　図３１の下方のグラフに、上記OH放出量から計算した膜中の水の量とP-Eヒステリシス曲線のシフト量との関係を示す。P-Eヒステリシス曲線のシフト量は膜中の水の量と相関があることが分かる。 The lower graph in FIG. 31 shows the relationship between the amount of water in the film calculated from the above-mentioned OH release amount and the shift amount of the PE hysteresis curve. It can be seen that the shift amount of the PE hysteresis curve is correlated with the amount of water in the membrane.
　（実施例２４：水／アルコール混合溶媒）
　実施例１と同様にして、ただし加熱温度を240℃に代えて200℃と180℃で堆積したKNN膜について、赤外線吸収分析（ＦＴＩＲ）をしたときの吸収強度パターンを実施例１の加熱温度が240℃の場合を含めて、図３２（ａ）に示す。図３２（ａ）において吸収強度は任意単位であり、吸収パターンだけが意味を有する。図３２（ａ）によると、180℃で堆積したKNN膜はＯＨ－を多く含み、ＯＨ－の量が200℃で堆積したKNN膜、240℃で堆積したKNN膜の順で少なくなっていることが分かる。 (Example 24: water / alcohol mixed solvent)
For the KNN film deposited at 200 ° C. and 180 ° C. in the same manner as in Example 1 except that the heating temperature is changed to 240 ° C., the absorption intensity pattern when infrared absorption analysis (FTIR) is performed is shown in FIG. It shows in FIG. 32 (a) including the case of 240 degreeC. In FIG. 32 (a), the absorption intensity is an arbitrary unit, and only the absorption pattern has meaning. According in FIG. 32 (a), the KNN film deposited at 180 ° C. OH - hints lot, OH - KNN film amount was deposited at 200 ° C. of, it has become less in the order of KNN film deposited at 240 ° C. I understand.
　実施例１と同様にして、すなわち、加熱温度を240℃にして、ただし、オートクレーブ内の水溶媒を水／アルコール混合溶媒（混合重量比８．０／１．６）に代えてKNN膜を堆積した。 In the same manner as in Example 1, that is, the heating temperature is 240 ° C., but the water solvent in the autoclave is replaced with a water / alcohol mixed solvent (mixing weight ratio 8.0 / 1.6) to deposit a KNN film. did.
　実施例１において水溶媒中に生成したKNN粉体と、実施例１及び実施例２４で得られたKNN膜とについて、試料を昇温して脱ガス質量スペクトル（TDS)で水分量を評価した結果を図３２（ｂ）に示す。図３２（ｂ）によれば、結晶内に取り込まれているOHが放出されるピーク（400～500℃付近）における水分量が、KNN膜ではKNN粉体と比べて２．８分の１と少なく、水／アルコール混合溶媒で得られたKNN膜では水溶媒で得られたKNN膜と比べて５分の１以下に低減している。したがって、水／アルコール混合溶媒を用いることで、KNN膜中の水分量が大幅に減少していること、KNN膜中の水分量は溶媒の組成を変えて制御できることが確認される。 The water content of the KNN powder produced in the water solvent in Example 1 and the KNN films obtained in Example 1 and Example 24 was evaluated by heating the sample and degassing mass spectrum (TDS). The results are shown in FIG. 32 (b). According to FIG. 32 (b), the water content at the peak (near 400 to 500 ° C.) from which OH incorporated in the crystal is released is 2.8 times smaller than that of the KNN powder in the KNN film. The KNN film obtained with the water / alcohol mixed solvent is reduced to one fifth or less compared to the KNN film obtained with the water solvent. Therefore, it is confirmed that the water content in the KNN film is greatly reduced and the water content in the KNN film can be controlled by changing the composition of the solvent by using the water / alcohol mixed solvent.
　（実施例２５：疲労特性）
　実施例２２と同様に、as depo.、300℃熱処理、600℃熱処理のKNN膜の両面を電極で挟持して作製した圧電素子の一端を固定して、カンチレバーを作成し、圧電素子に電圧１０V、周波数１ｋHｚの交流電圧を印加してカンチレバー（圧電素子）の駆動を繰り返して、疲労特性を評価した。いずれにおいても、10,000,000サイクル後も圧電性は変化が認められなかった。 (Example 25: Fatigue Property)
As in Example 22, one end of a piezoelectric element manufactured by holding both surfaces of a KNN film heat-treated as depo., 300 ° C. and 600 ° C. with an electrode is fixed to form a cantilever, and a voltage of 10 V is applied to the piezoelectric element. An alternating voltage with a frequency of 1 kHz was applied to repeatedly drive the cantilever (piezoelectric element) to evaluate fatigue characteristics. In any case, no change was observed in the piezoelectricity even after 10,000,000 cycles.
　また、300℃熱処理、600℃熱処理したKNN膜の圧電素子について、250℃で熱処理したが、特性劣化、脱分極は観察されなかった。 The piezoelectric element of the KNN film heat-treated at 300 ° C. and 600 ° C. was heat-treated at 250 ° C., but no characteristic deterioration and no depolarization were observed.
　（実施例２６：ポリスルホン箔基板）
　実施例２と同様にして、ただし、基板として可撓性のポリスルホン箔（500μｍ厚）上にLaNiO3膜（100nm厚）を堆積した基板（LaNiO3/Pt/Ti/ポリスルホン)を用い、アルカリとして水酸化カリウムだけを用いて、製膜温度150℃で、厚さ10μｍのKNbO3膜を製膜し、ペロブスカイト構造単相であるKNbO3膜が得られた。 (Example 26: Polysulfone foil substrate)
In the same manner as in Example 2, except that a substrate (LaNiO 3 / Pt / Ti / polysulfone) in which a LaNiO 3 film (100 nm thick) is deposited on a flexible polysulfone foil (500 μm thick) as a substrate is used as an alkali Using only potassium hydroxide, a 10 μm thick KNbO 3 film was formed at a film forming temperature of 150 ° C. to obtain a KNbO 3 film having a single phase of perovskite structure.
　また、3.0cmx0.75cmのポリスルホン箔上にスパッタでPt/Ti膜を下部電極として堆積してから、その上にLaNiO3膜（100nm厚）を堆積した基板（LaNiO3/Pt/Ti/ポリスルホン)を用い、KNbO3膜を上記と同様にして厚さ10μｍ製膜し、その上にPt電極を上部電極として蒸着して、圧電素子モデルを作製した。得られた圧電素子モデルは曲率半径10mmまで曲げることができ、KNbO3膜にマクロな剥離やクラックはなかった。 Also, after depositing a Pt / Ti film as a lower electrode by sputtering on a 3.0 cm × 0.75 cm polysulfone foil, a substrate on which a LaNiO 3 film (100 nm thickness) was deposited (LaNiO 3 / Pt / Ti / polysulfone) A KNbO 3 film was formed to a thickness of 10 μm in the same manner as described above, and a Pt electrode was deposited thereon as a top electrode to fabricate a piezoelectric element model. The obtained piezoelectric element model was able to be bent to a radius of curvature of 10 mm, and there was no macro peeling or crack in the KNbO 3 film.
　この圧電素子モデルにおいて圧電特性に起因する電界-電界誘起歪（S-E）曲線が観測され、有機基板上で圧電特性を示すことから、圧電素子であることが確認された。この素子の圧電特性ｄ33は約30pm/Vであり、有機圧電体PVDFのｄ33=23pm/Vと比べても優れている。 In this piezoelectric element model, an electric field-electric field induced strain (SE) curve caused by the piezoelectric property was observed, and the piezoelectric property was confirmed on the organic substrate, which confirmed that the element was a piezoelectric element. Piezoelectric properties d 33 of the device is about 30 pm/V, it is excellent in comparison with d 33 = 23pm / V of the organic piezoelectric PVDF.
　さらに、５０μmのインコネル上に作製した、KNN/SrRuO3/インコネル圧電素子に振動を与えて発電の出力電圧を測定すると、周波数105Hzで出力電圧約９Vが観測された。 Furthermore, when vibration was applied to a KNN / SrRuO 3 / inconel piezoelectric element fabricated on a 50 μm inconel to measure an output voltage of power generation, an output voltage of about 9 V was observed at a frequency of 105 Hz.
　図３３に、観測された発電特性の変化と、圧電素子の基礎特性から計算される出力電力の変化（破線）を示しており、非常によく一致していることが分かった。また、最大出力電力は約3.6μWであった。 FIG. 33 shows the observed change in power generation characteristics and the change in output power (dotted line) calculated from the basic characteristics of the piezoelectric element, and it was found that they coincide very well. In addition, the maximum output power was about 3.6 μW.
　発電素子の出力電力密度は1.7μW/G2/mm3であり、従来KNN膜において報告されている200Hz以下の周波数帯での出力電力密度（0.5μW/G2/mm3以下）と比べても大きい。
　（実施例２７：U字形、巻回の基板）
　長さ3cm、幅0.75cm、厚さ50μｍのインコネル（登録商標）金属箔の表面にSrRuO3膜を50nm堆積したバッファ層（SrRuO3）を有する金属箔（SrRuO3//金属箔）を用い、この金属箔を曲率半径約5.3mmのU字形に曲げ、金属箔の端部をテフロンの溝に埋め込んで作成した基板を用いて、実施例１と同様の手順で、KNN膜を作製した。膜厚は約１４μｍであった。 The output power density of the power generation element is 1.7 μW / G 2 / mm 3 , compared to the output power density (0.5 μW / G 2 / mm 3 or less) in the frequency band of 200 Hz or less conventionally reported for KNN films. Too big.
(Example 27: U-shaped, wound substrate)
A metal foil (SrRuO 3 // metal foil) having a buffer layer (SrRuO 3 ) in which a 50 nm thick SrRuO 3 film is deposited on the surface of Inconel® metal foil having a length of 3 cm, a width of 0.75 cm and a thickness of 50 μm A KNN film was produced in the same manner as in Example 1 using a substrate prepared by bending this metal foil into a U shape having a curvature radius of about 5.3 mm and embedding the end of the metal foil in a Teflon groove. The film thickness was about 14 μm.
　また、上記と同様の金属箔（SrRuO3//金属箔）を用い、最大直径が約0.8cmのゼンマイの形状（２周半の巻回）に曲げ加工した基板を用いて、実施例１と同様の手順で、KNN膜を作製した。膜厚は約１２μｍであった。 In addition, using the same metal foil (SrRuO 3 // metal foil) as described above, using a substrate bent to the shape of a spiral spring (two turns and a half turns) having a maximum diameter of about 0.8 cm, Example 1 and A KNN film was produced in the same manner. The film thickness was about 12 μm.
　上記のいずれにおいてもKNN膜は、{100}及び{110}配向した結晶が混在しているが一軸配向したペロブスカイト構造の配向膜であり、SrRuO3膜は{100}配向していた。またこれらの湾曲基板上に製膜したKNN膜の圧電特性は、P-Eヒステリシス曲線における残留分極及び抗電界、I-V特性、漏れ電流のいずれにおいても、基板が平坦である場合と同等の良好な圧電特性を示した。 In any of the above cases, the KNN film is an orientation film of a perovskite structure in which crystals with {100} and {110} orientation are mixed, but uniaxially oriented, and the SrRuO 3 film is {100} orientation. The piezoelectric characteristics of the KNN films formed on these curved substrates are good as in the case where the substrate is flat, in any of the residual polarization and coercive electric field in the PE hysteresis curve, the IV characteristics and the leakage current. showed that.
　（実施例２８：マイクロ波加熱）
　実施例１においてはオートクレーブ内を電気発熱体によって240℃に加熱して製膜したが、実施例２８では、図３４(ａ)～(ｃ)に示すように、オートクレーブに代えて、マイクロ波加熱可能な反応装置（"flexiWAVE", Milestone General（登録商標））４０内に配置した耐アルカリ性、耐圧性の反応容器（テフロン／PEEKの二重容器)４１内に入れた水溶液４２にマイクロ波を照射し、光ファイバで容器内の温度を観測しながら、設定温度220℃に加熱して、その他は実施例１と同様の条件で。基板４３に製膜した。 (Example 28: Microwave heating)
In Example 1, the inside of the autoclave was heated to 240 ° C. by an electric heating element, but in Example 28, as shown in FIGS. 34 (a) to (c), the autoclave was replaced with microwave heating, Of the aqueous solution 42 contained in an alkali-resistant, pressure-resistant reaction vessel (Teflon / PEEK double vessel) 41 arranged in a possible reactor ("flexiWAVE", Milestone General®) 40 Then, while observing the temperature inside the container with an optical fiber, heat to a set temperature of 220 ° C., under the same conditions as Example 1. The film was formed on the substrate 43.
　マイクロ波加熱で得られたKNN膜の組成、結晶性、配向性、圧電特性は、通常の加熱で得られたKNN膜と同様であった。 The composition, crystallinity, orientation, and piezoelectric properties of the KNN film obtained by microwave heating were similar to those of the KNN film obtained by normal heating.
　その結果、マイクロ波加熱を用いると、通常加熱の場合と比べて製膜時間を大幅に短縮でき、例えば、従来数時間を要した膜厚のKNN膜を１時間以下の短時間で製膜できた。 As a result, when microwave heating is used, the film forming time can be significantly shortened compared to the case of normal heating, and for example, a KNN film having a film thickness requiring several hours can be formed in a short time of 1 hour or less The
１：　反応容器
２：　水（アルカリ水溶液）
３：　ニオブ／タンタル系酸化物
４：　基板
５：　取付具
１０：圧電素子
１１：基板
１２：下部電極
１３：ニオブ／タンタル酸アルカリ系膜
１４：上部電極
１５：バッファ層
２０：超音波プローブ
２１：バッキング材
２２：振動子（圧電素子）
２３：音響整合器
２４：音響レンズ
３０：焦電発電装置
３１：焦電素子
３２：強誘電体
３３：電極
３４：熱源 1: Reaction vessel 2: Water (alkaline aqueous solution)
3: Niobium / tantalum-based oxide 4: Substrate 5: Mounting tool 10: Piezoelectric element 11: Substrate 12: Lower electrode 13: Niobium / alkali tantalate film 14: Upper electrode 15: Buffer layer 20: Ultrasonic probe 21: Backing material 22: vibrator (piezoelectric element)
23: Acoustic matching unit 24: Acoustic lens 30: Pyroelectric generator 31: Pyroelectric element 32: Ferroelectric 33: Electrode 34: Heat source

Claims (28)

  1. 　反応容器内において、水酸化アルカリと、非晶質ニオブ／タンタル系酸化物とを含む水含有溶媒中に、基体を浸漬し、加熱及び加圧して、前記基体上にペロブスカイト系の結晶構造を有するニオブ／タンタル酸アルカリ系膜を堆積すること、前記ニオブ／タンタル系酸化物は、平均組成式（Ｎｂ１－ｘＴａｘ）２Ｏ５（式中、０≦ｘ≦１である。）で表される酸化ニオブ、酸化タンタルの単体、固溶体またはそれらの混合物であり、それらは水和物でもよく、前記ニオブ／タンタル酸アルカリ系膜は、式Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３（式中、Ａはアルカリ金属の１種または２種以上であり、２種以上のアルカリ金属の割合は任意であり、０≦ｘ≦１である。）で表されるニオブ／タンタル酸アルカリを含む結晶であることを特徴とする、ニオブ／タンタル酸アルカリ系膜の製造方法。 In the reaction vessel, the substrate is immersed in a water-containing solvent containing alkali hydroxide and amorphous niobium / tantalum oxide, heated and pressurized to have a perovskite crystal structure on the substrate. Depositing a niobium / tantalate alkali based film, said niobium / tantalum based oxide having an average compositional formula (Nb 1-x Ta x ) 2 O 5 (wherein 0 ≦ x ≦ 1). Of niobium oxide or tantalum oxide alone, a solid solution or a mixture thereof, which may be a hydrate, and the niobium / tantalate alkali based film has a formula A (Nb 1-x Ta x ) O 3 (formula Among them, A is one or two or more alkali metals, and the ratio of two or more alkali metals is arbitrary, and a crystal containing an alkali of niobium / tantalate represented by 0 ≦ x ≦ 1) Is characterized by That method niobium / tantalum alkali-based film.
  2. 　前記基体が平面及び／又は曲面を含む表面を有し、得られるニオブ／タンタル酸アルカリ系膜の膜厚が７０μｍ以上（前記式中のＡの９６％以上がカリウムである場合は１４０μｍ以上）である、請求項１に記載の製造方法。 The substrate has a surface including a flat surface and / or a curved surface, and the film thickness of the obtained niobium / tantalate alkali type film is 70 μm or more (140 μm or more when 96% or more of A in the above formula is potassium) The manufacturing method according to claim 1.
  3. 　前記水酸化アルカリと前記非晶質ニオブ／タンタル系酸化物とのモル比が、１：１．０×１０－４～１：１．０×１０５である、請求項１又は２に記載の製造方法。 The molar ratio of the alkali hydroxide to the amorphous niobium / tantalum oxide is in the range of 1: 1.0 × 10 -4 to 1: 1.0 × 10 5 . Production method.
  4. 　前記水酸化アルカリが、水酸化カリウム及び／又は水酸化ナトリウム及び／又は水酸化リチウムである、請求項１～３のいずれか一項に記載の製造方法。 The method according to any one of claims 1 to 3, wherein the alkali hydroxide is potassium hydroxide and / or sodium hydroxide and / or lithium hydroxide.
  5. 　前記水酸化カリウムと前記水酸化ナトリウムとの合計に対する前記水酸化カリウムのモル比（[KOH]/([KOH]+[NaOH])）が、０．6～１．０である、請求項４に記載の製造方法。 The molar ratio ([KOH] / ([KOH] + [NaOH])) of the potassium hydroxide to the total of the potassium hydroxide and the sodium hydroxide is 0.6 to 1.0. The manufacturing method described in.
  6. 　前記水酸化カリウムと前記水酸化ナトリウムと前記水酸化リチウムとの合計に対する前記水酸化リチウムのモル比（[LiOH]/([KOH]+[NaOH]+[LiOH]）が、０～０．１である、請求項４に記載の製造方法。 The molar ratio ([LiOH] / ([KOH] + [NaOH] + [LiOH]) of the lithium hydroxide to the total of the potassium hydroxide, the sodium hydroxide and the lithium hydroxide is 0 to 0.1 The manufacturing method of Claim 4 which is.
  7. 　前記水含有溶媒中の前記水酸化アルカリの濃度が０．１～３０モル／Ｌである、請求項１～６のいずれか一項に記載の製造方法。 The method according to any one of claims 1 to 6, wherein the concentration of the alkali hydroxide in the water-containing solvent is 0.1 to 30 mol / L.
  8. 　前記水性溶媒中にＣａＯ、ＣｕＯ、ＭｎＯ２、Ｓｂ２Ｏ３、ＢａＯ、ＺｒＯ２及びＴｉＯ2から選ばれる酸化物の原料をさらに含み、前記ニオブ／タンタル酸アルカリ系膜が、ＣａＯ、ＣｕＯ、ＭｎＯ２、Ｓｂ２Ｏ３、ＢａＯ、ＺｒＯ２及びＴｉＯ2から選ばれる酸化物をさらに含む、請求項１～７のいずれか一項に記載の製造方法。 The aqueous solvent further includes a raw material of an oxide selected from CaO, CuO, MnO 2 , Sb 2 O 3 , BaO, ZrO 2 and TiO 2, and the niobium / tantalate alkali based film comprises CaO, CuO, MnO The production method according to any one of claims 1 to 7, further comprising an oxide selected from 2 , Sb 2 O 3 , BaO, ZrO 2 and TiO 2 .
  9. 　前記基体がペロブスカイト系の結晶構造を有する、請求項１～８のいずれか一項に記載の製造方法。 The method according to any one of claims 1 to 8, wherein the substrate has a perovskite crystal structure.
  10. 　前記基体が、半導体、金属、プラスチック、セラミックスから選ばれる材料からなり、その表面にペロブスカイト系の結晶構造のバッファ層を有する基体である、請求項１～９のいずれか一項に記載の製造方法。 The method according to any one of claims 1 to 9, wherein the substrate is a substrate made of a material selected from semiconductors, metals, plastics, and ceramics, and having a buffer layer of a perovskite crystal structure on the surface thereof. .
  11. 　前記基体が導電性基体である、請求項１～１０のいずれか一項に記載の製造方法。 The method according to any one of claims 1 to 10, wherein the substrate is a conductive substrate.
  12. 　前記反応容器が密封容器であり、前記反応容器内の温度を５０～３００℃の温度に加熱する、請求項１～１１のいずれか一項に記載の製造方法。 The production method according to any one of claims 1 to 11, wherein the reaction vessel is a sealed vessel, and the temperature in the reaction vessel is heated to a temperature of 50 to 300 属 C.
  13. 　前記加熱を、マイクロ波を用いて行う、請求項１～１２のいずれか一項に記載の製造方法。 The manufacturing method according to any one of claims 1 to 12, wherein the heating is performed using a microwave.
  14. 　前記ニオブ／タンタル酸アルカリ系膜が、一軸配向又はエピタキシャル配向した結晶を含む、請求項１～１３のいずれか一項に記載の製造方法。 The method according to any one of claims 1 to 13, wherein the niobium / tantalate alkali-based film contains a uniaxially or epitaxially oriented crystal.
  15. 　前記ニオブ／タンタル酸アルカリ系膜が分極処理なしで分極方向が揃っている、請求項１４に記載の製造方法。 15. The manufacturing method according to claim 14, wherein the niobium / tantalate alkali based film has a uniform polarization direction without polarization treatment.
  16. 　前記ニオブ／タンタル酸アルカリ系膜を、前記水含有媒中から取り出した後、１００～７５０℃の温度でアニールする、請求項１～１５のいずれか一項に記載の製造方法。 The method according to any one of claims 1 to 15, wherein the niobium / tantalate alkali type film is removed from the water-containing medium and then annealed at a temperature of 100 to 750 属 C.
  17. 　前記ニオブ／タンタル酸アルカリ系膜が圧電特性を示す、請求項１～１６のいずれか一項に記載の製造方法。 The method according to any one of the preceding claims, wherein the niobium / tantalate alkali-based film exhibits piezoelectric properties.
  18. 　請求項１～１７のいずれか一項に記載の製造方法で製造されることを特徴とする一軸配向又はエピタキシャル配向したニオブ／タンタル酸アルカリ系膜。 A uniaxially or epitaxially oriented niobium / tantalate alkali based film produced by the method according to any one of claims 1 to 17.
  19. 　式Ａ（Ｎｂ１－ｘＴａｘ）Ｏ３（式中、Ａはアルカリ金属の１種または２種以上であり、２種以上のアルカリ金属の割合は任意であり、０≦ｘ≦１である。）で表され、一軸配向又はエピタキシャル配向した結晶を含むニオブ／タンタル酸アルカリ系膜であって、前記ニオブ／タンタル酸アルカリ系膜が、７０μｍ以上（前記式中のＡの９６モル％以上がカリウムである場合は１４０μｍ以上）の厚さを有するか及び／又は曲面を含む基体上に形成されていることを特徴とするニオブ／タンタル酸アルカリ系膜。 Formula A (Nb 1-x Ta x ) O 3 (wherein, A is one or more alkali metals, and the ratio of two or more alkali metals is arbitrary, and 0 ≦ x ≦ 1. And a niobium / tantalate alkali type film containing crystals uniaxially or epitaxially oriented, wherein the niobium / tantalate alkali type film is 70 μm or more (96 mol% or more of A in the above formula is A niobium / tantalate alkali based film having a thickness of 140 μm or more in the case of potassium and / or being formed on a substrate including a curved surface.
  20. 　前記ニオブ／タンタル酸アルカリ系膜が分極処理なしで分極方向が揃っている、請求項１８又は１９に記載のニオブ／タンタル酸アルカリ系膜。 20. The niobium / tantalate alkali based film according to claim 18, wherein the niobium / tantalate alkali based film has the same polarization direction without polarization treatment.
  21. 　前記ニオブ／タンタル酸アルカリ系膜がペロブスカイト系の結晶構造を有する基体上に形成されている、請求項１８～２０のいずれか一項に記載のニオブ／タンタル酸アルカリ系膜。 The alkali niobium / tantalate film according to any one of claims 18 to 20, wherein the niobium / tantalate alkali film is formed on a substrate having a perovskite crystal structure.
  22. 　前記基体が前記ニオブ／タンタル酸アルカリ系膜と接する導電性表面を有する、請求項２１に記載のニオブ／タンタル酸アルカリ系膜。 22. The niobium / tantalate alkali based film according to claim 21, wherein the substrate has a conductive surface in contact with the niobium / tantalate alkali based film.
  23. 　前記基体が半導体、金属、プラスチック、セラミックスから選ばれる材料を含み、その材料と前記ニオブ／タンタル酸アルカリ系膜との間にペロブスカイト構造のバッファ層を有する基体である、請求項１８～２２のいずれか一項に記載のニオブ／タンタル酸アルカリ系膜。 The substrate according to any one of claims 18 to 22, wherein the substrate comprises a material selected from semiconductors, metals, plastics, and ceramics, and has a buffer layer of a perovskite structure between the material and the niobium / tantalate alkali type film. The niobium / tantalate alkali based film according to any one of the preceding claims.
  24. 　圧電又は焦電特性を利用する機能性装置であって、前記圧電又は焦電素子が請求項１８～２３のいずれか一項に記載のニオブ／タンタル酸アルカリ系膜と電極とを含む圧電素子を含み、前記機能性装置が、医療用超音波プローブ、超音波トランスミッタ、超音波センサ、焦電発電装置、振動発電装置、アクチュエータから選ばれることを特徴とする機能性装置。 A functional device using piezoelectric or pyroelectric properties, wherein the piezoelectric or pyroelectric element includes an alkali niobium / tantalate based film according to any one of claims 18 to 23, and an electrode. A functional device, characterized in that the functional device is selected from a medical ultrasonic probe, an ultrasonic transmitter, an ultrasonic sensor, a pyroelectric generator, a vibration generator, and an actuator.
  25. 　前記機能性装置が、２～１００ＭＨｚの超音波を発信又は受信できる超音波プローブ用トランスデューサを含む、請求項２４に記載の機能性装置。 The functional device according to claim 24, wherein the functional device comprises a transducer for an ultrasonic probe capable of transmitting or receiving ultrasonic waves of 2 to 100 MHz.
  26. 　前記機能性装置が、前記超音波プローブ用トランスデューサを用いて、皮膚の表面下深度２０ｍｍ以内の領域を画像診断することができる超音波造影装置である、請求項２４に記載の機能性装置。 The functional device according to claim 24, wherein the functional device is an ultrasonic imaging device capable of diagnostic imaging of an area within a depth of 20 mm below the surface of the skin using the transducer for ultrasonic probe.
  27. 　前記機能性装置が、前記超音波プローブ用トランスデューサを用いて、人体の組織に対して医療的処置を行うことができる医療用装置である、請求項２４に記載の機能性装置。 The functional device according to claim 24, wherein the functional device is a medical device capable of performing a medical treatment on tissue of a human body using the transducer for ultrasonic probe.
  28. 　前記機能性装置が、２００Ｈｚ以下の共振周波数において１μＷ・Ｇ－２ｍｍ－３以上の出力電力密度を有する発電装置である、請求項２４に記載の機能性装置。 The functional device according to claim 24, wherein the functional device is a power generation device having an output power density of 1 μW · G -2 mm -3 or more at a resonance frequency of 200 Hz or less.
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