WO2022153680A1 - Piezoelectric ceramic, piezoelectric element, and ultrasonic vibrator - Google Patents

Piezoelectric ceramic, piezoelectric element, and ultrasonic vibrator Download PDF

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WO2022153680A1
WO2022153680A1 PCT/JP2021/043157 JP2021043157W WO2022153680A1 WO 2022153680 A1 WO2022153680 A1 WO 2022153680A1 JP 2021043157 W JP2021043157 W JP 2021043157W WO 2022153680 A1 WO2022153680 A1 WO 2022153680A1
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piezoelectric
piezoelectric element
piezoelectric ceramics
maximum peak
peak intensity
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PCT/JP2021/043157
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French (fr)
Japanese (ja)
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智宏 原田
朋弥 相澤
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太陽誘電株式会社
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
    • C04B35/49—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates containing also titanium oxides or titanates
    • C04B35/491—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates containing also titanium oxides or titanates based on lead zirconates and lead titanates, e.g. PZT
    • 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
    • H10N30/08—Shaping or machining of piezoelectric or electrostrictive bodies
    • H10N30/085—Shaping or machining of piezoelectric or electrostrictive bodies by machining
    • H10N30/089—Shaping or machining of piezoelectric or electrostrictive bodies by machining by punching
    • 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
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • 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
    • 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
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals

Definitions

  • the present invention relates to piezoelectric ceramics, piezoelectric elements and ultrasonic vibrators.
  • Piezoelectric elements are used in sensor elements, power generation elements, etc. by utilizing the positive piezoelectric effect that converts mechanical energy into electrical energy. Piezoelectric elements are also used in vibrators, sounding bodies, actuators, ultrasonic motors, pumps, etc. by utilizing the inverse piezoelectric effect of converting electrical energy into mechanical energy. Further, the piezoelectric element is also used in a circuit element, a vibration control element, and the like by using the positive piezoelectric effect and the inverse piezoelectric effect in combination.
  • the piezoelectric transformer, vibrator, ultrasonic motor, etc. are continuously driven under conditions where a large amplitude such as a resonance point is generated, so that the element itself tends to generate heat. Since the heat generated by the piezoelectric element leads to deterioration or loss of the piezoelectric characteristics, it is necessary to suppress this.
  • the heat generated by the piezoelectric element is caused by mechanical loss and electrical loss that occur during driving. Therefore, as the piezoelectric element as described above, the above-mentioned material having both small losses, which is called a hard piezoelectric material or a hard material, is used.
  • the mechanical quality coefficient Qm is high as an index of the small mechanical loss and that the dielectric loss tang tan ⁇ is small as an index of the small electrical loss.
  • lead zirconate titanate (Pb (Zr, Ti) O 3 : PZT) having a perovskite-type structure is used as a basic composition, and various elements are dissolved therein. The one with low loss has been proposed.
  • a piezoelectric composition having a high mechanical quality coefficient Qm and capable of firing at a relatively low temperature a compound containing Pb, Zn, Nb, Ti, Zr and O as constituent elements and having a perovskite-type structure is mainly used. Those used as ingredients are known (Patent Documents 1 and 2).
  • the area ratio of crystal particles having a domain size of 100 nm or less is set to 30% or more as a means for increasing the mechanical quality coefficient Qm of PZT-based piezoelectric ceramics (Patent Document 3).
  • the piezoelectric ceramics described in Patent Document 3 have a small domain size in the ceramic particles, the number of domain walls that are boundaries between domains increases. It is said that the domain wall in the ceramic particles moves in the particles when the piezoelectric element is driven at high speed and large amplitude, and this movement causes mechanical loss. Therefore, the piezoelectric ceramics described in Patent Document 3 including a large number of domain walls are concerned that the mechanical loss becomes large when the piezoelectric element formed by the piezoelectric ceramics is driven at high speed and large amplitude.
  • an object of the present invention is to provide piezoelectric ceramics capable of stably obtaining a piezoelectric element having a small mechanical loss when driven at a high speed and a large amplitude.
  • the present inventor has conducted various studies to solve the above problems, and found that the piezoelectric ceramic contains a Zn-containing oxide having a crystal structure different from that of the compound having a perovskite structure. We have found that the problem can be solved and have completed the present invention.
  • one aspect of the present invention for solving the above-mentioned problems is that a compound containing Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements and having a perovskite-type structure as a main component and Cu—K ⁇ is used as a main component.
  • another aspect of the present invention is a piezoelectric element including the above-mentioned piezoelectric ceramics and an electrode electrically connected to the piezoelectric ceramics.
  • another aspect of the present invention is an ultrasonic vibrator including the above-mentioned piezoelectric element and a pair of block bodies that sandwich the piezoelectric element from the uniaxial direction.
  • piezoelectric ceramics capable of stably obtaining a piezoelectric element having a small mechanical loss when driven at a high speed and a large amplitude.
  • FIG. 1 Schematic perspective view showing the structure of the laminated piezoelectric element according to one aspect of the present invention.
  • Left side view of the laminated piezoelectric element shown in FIG. AA'cross-sectional view of the laminated piezoelectric element shown in FIG.
  • “driving at high speed and large amplitude" of the piezoelectric element means driving at a resonance frequency or driving under a condition that the vibration speed measured by a laser Doppler vibrometer is 0.62 m / s or more. To say.
  • the piezoelectric ceramics according to one aspect of the present invention (hereinafter, may be simply referred to as “first aspect”) contain Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements, and have a perovskite-type structure.
  • the first aspect contains Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements and contains a compound having a perovskite-type structure as a main component.
  • the compound having a perovskite structure is mainly composed of Pb (Zr, Ti) O 3 -Pb (Zn, Nb) O 3 -Pb (Mn, Nb) O 3 , and when it is used as a piezoelectric element. , A large amount of displacement can be obtained with respect to the applied voltage, and mechanical loss during driving can be suppressed.
  • composition formula is represented by the following formula (1) in that a larger displacement amount and a lower mechanical loss can be achieved.
  • the first aspect is represented by the above formula (1) that it contains Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements, and that the main component is a compound having a perovskite-type structure. It is confirmed by the following procedure that each of them has the same composition.
  • the piezoelectric ceramics are crushed to prepare a powdery sample.
  • the piezoelectric ceramics form a piezoelectric element, it is preferable to remove parts other than the piezoelectric ceramics such as electrodes and coatings and then pulverize the parts.
  • the entire element may be crushed into a powder sample.
  • the diffraction line profile of the obtained powdered sample was measured by an X-ray diffractometer (XRD) using Cu—K ⁇ rays, and diffraction from another structure with respect to the strongest diffraction line intensity in the profile derived from the perovskite structure.
  • XRD X-ray diffractometer
  • the piezoelectric ceramics are mainly composed of a compound having a perovskite type structure.
  • the piezoelectric ceramic part is crushed together with the piezoelectric element into a powder sample without being separated from other parts, it is clear that the peak is derived from a part other than the piezoelectric ceramic such as an electrode in the diffraction line profile.
  • the powdery sample confirmed to contain a compound having a perovskite-type structure as a main component is composed by high-frequency inductively coupled plasma (ICP) emission spectroscopic analysis, ion chromatography device, or fluorescent X-ray (XRF) analysis device. Perform analysis. Then, from the result of the composition analysis, the presence or absence of each element other than oxygen is confirmed, and when the existence is confirmed, it is determined that the piezoelectric ceramic contains each of the above elements. Further, the composition of the piezoelectric ceramic is represented by the formula (1) when the content ratio of an element other than oxygen is calculated from the result of the composition analysis and the content ratio is the ratio in the formula (1). It is judged that it has.
  • ICP inductively coupled plasma
  • XRF fluorescent X-ray
  • the first aspect may contain other additive elements or compounds as long as each of the above-mentioned elements is contained as a constituent element and the main component is a compound having a perovskite-type structure.
  • additive elements include Ca, Sr, Ba, Ag, La, Ce and Bi, which are solid-solved in A-site in the perovskite-type structure represented by ABO 3 , and Mg, Fe, Co. , Ni, Ta, W and the like.
  • the compound include glassy grain boundary phases derived from components added to lower the sintering temperature.
  • the first aspect is 34.0 ° ⁇ 2 ⁇ ⁇ 35.0 ° with respect to the maximum peak intensity IP appearing at 20.0 ° ⁇ 2 ⁇ ⁇ 40.0 ° in X - ray diffraction measurement using Cu-K ⁇ rays.
  • the total ratio of the maximum peak intensity I ZT that appears and the maximum peak intensity I ZnO that appears at 35.5 ° ⁇ 2 ⁇ ⁇ 37.0 ° ( ⁇ (I ZT + I ZnO ) / IP ⁇ x 100) (hereinafter, "Zn” It may be described as "containing oxide ratio"), but it is 0.3% or more.
  • Zn It may be described as "containing oxide ratio"
  • the maximum peak intensity IP in which 2 ⁇ appears in the range of 20.0 ° to 40.0 ° is the perovskite type, which is the main component. It is derived from a compound having a structure.
  • the maximum peak intensity I ZT in which 2 ⁇ appears in the range of 34.0 ° to 35.0 ° is an oxide containing Zn and Ti (Zn p Ti q Or (however, p, q and r are real numbers, respectively)).
  • the maximum peak I ZnO in which 2 ⁇ appears in the range of 35.5 ° to 37.0 ° is derived from zinc oxide (ZnO).
  • the large value of the Zn - containing oxide ratio which is the total ratio of I ZT and I ZnO to IP, means that the content ratio of Zn-containing oxide having a crystal structure different from that of the perovskite type structure is relatively high. It means high. Then, when this ratio is 0.3% or more, a piezoelectric element having a high mechanical quality coefficient Qm can be obtained. The reason for this is not clear at this time, but since the origin of Zn and / or Ti, which are constituent elements of the Zn-containing oxide, is a compound having a perovskite-type structure, the formation of the Zn-containing oxide causes the perovskite-type structure.
  • the Zn-containing oxide ratio is preferably 0.5% or more, and more preferably 1.0% or more.
  • the upper limit of the Zn-containing oxide ratio is 10% or less as described above because the first side surface is mainly composed of a compound having a perovskite-type structure.
  • the Zn-containing oxide ratio is preferably 5% or less from the viewpoint of obtaining a piezoelectric element having a large displacement amount per applied voltage by increasing the proportion of the perovskite-type structure compound as the main component.
  • the Zn-containing oxide ratio is calculated by the following procedure. First, the piezoelectric ceramic is prepared as a powder sample by the method described above, and its XRD profile is measured. Next, the obtained results were analyzed using software for crystal structure analysis (JADE, manufactured by Lightstone Co., Ltd.), and the maximum peak intensity IP at 20.0 ° ⁇ 2 ⁇ ⁇ 40.0 °, 34.0 °. The maximum peak intensity I ZT at ⁇ 2 ⁇ ⁇ 35.0 ° and the maximum peak I ZnO at 35.5 ° ⁇ 2 ⁇ ⁇ 37.0 ° are obtained. Finally, using the obtained I P , I ZT , and I ZnO , a value of ⁇ (I ZT + I ZnO ) / I P ⁇ ⁇ 100 is calculated, and this is used as the Zn-containing oxide ratio.
  • the average particle size ravg of the contained particles is 2.5 ⁇ m or more.
  • the average particle size ravg is more preferably 2.7 ⁇ m or more, further preferably 3.0 ⁇ m or more, and particularly preferably 3.5 ⁇ m or more.
  • the upper limit of the average particle size ravg is not particularly limited, but is preferably 10 ⁇ m or less from the viewpoint of suppressing a decrease in mechanical strength due to coarse particles.
  • the average particle size ravg in the first aspect is determined by the following procedure. First, platinum is vapor-deposited on the surface of the piezoelectric ceramic to impart conductivity, and the sample is used as a measurement sample. Regarding the piezoelectric ceramics in the piezoelectric element, if there is an exposed portion on the surface of the element, platinum is vapor-deposited on the portion to prepare a sample for measurement. If the piezoelectric ceramics are not exposed on the surface of the piezoelectric element, the piezoelectric ceramics are exposed by polishing, grinding, cutting, etching, etc., and then heat-treated at a temperature of 900 to 960 ° C for about 15 to 30 minutes (thermal).
  • the piezoelectric ceramic according to the first aspect is obtained by mixing, for example, a powder of a compound containing one or more elements selected from Pb, Zr, Ti, Zn and Nb to obtain a mixed powder containing each element. , The mixed powder is calcined to obtain a calcined powder, a compound containing Mn is mixed with the calcined powder, and then molded into a predetermined shape to obtain a molded body, and the molded body is fired. Manufactured after doing. This manufacturing method will be described below.
  • the composition and particle size of the powder of the compound used as a raw material are not limited as long as the piezoelectric ceramics according to the first aspect can be obtained by firing.
  • the compound constituting the powder may contain an additive element other than the above-mentioned elements.
  • examples of compounds that can be used include PbO and Pb 3O 4 as Pb-containing compounds, ZrO 2 and the like as Zr - containing compounds, TIO 2 and the like as Ti-containing compounds, ZnO and the like as Zn-containing compounds, and Nb-containing compounds. Examples include Nb 2 O 5 and the like.
  • the mixing method of the raw material powder is not particularly limited as long as each powder is uniformly mixed while preventing the mixing of impurities, and either dry mixing or wet mixing may be adopted. When wet mixing using a ball mill is adopted, it may be mixed for about 8 to 24 hours, for example.
  • the calcination conditions are not limited as long as each raw material reacts to obtain a calcination powder containing a perovskite-type compound represented by the above-mentioned composition formula as a main component.
  • a calcination powder containing a perovskite-type compound represented by the above-mentioned composition formula as a main component For example, in an air atmosphere, 700 ° C. to 1000 ° C. The temperature may be 2 to 8 hours. If the firing temperature is too low or the firing time is too short, unreacted raw materials and intermediate products may remain. On the other hand, if the firing temperature is too high or the firing time is too long, there is a risk that a compound having the desired composition cannot be obtained due to volatilization of Pb and Zn, and the product will solidify and become difficult to crush. There is a risk that productivity will decrease.
  • the composition and particle size of the Mn-containing compound to be mixed with the calcined powder are not limited as long as the piezoelectric ceramics according to the first aspect can be obtained by firing, as in the case of the raw material powder described above.
  • Examples of compounds that can be used include MnCO 3 .
  • the same method as the above-mentioned mixing method for the raw material powder can be adopted.
  • the Mn-containing compound may be mixed at the same time as the above-mentioned raw material powder, but it is preferable to mix the Mn-containing compound with the calcined powder because piezoelectric ceramics having a high Zn-containing oxide content can be easily obtained.
  • the calcined powder mixed with the Mn-containing compound As a method for molding the calcined powder mixed with the Mn-containing compound, it is usually used for molding ceramic powder such as uniaxial pressure molding of powder, extrusion molding of clay containing powder, and casting molding of slurry in which powder is dispersed. The method used can be adopted.
  • the piezoelectric ceramics are obtained as the piezoelectric ceramic layer 10 of the laminated piezoelectric element 100 shown in FIGS. 1 to 3, the following molding method can be adopted.
  • the calcined powder mixed with the Mn-containing compound is mixed with a binder or the like to form a slurry or clay, and then this is molded into a sheet to obtain a raw sheet containing the calcined powder.
  • a sheet molding method a commonly used method such as a doctor blade method or an extrusion molding method can be adopted.
  • an electrode pattern that becomes the internal electrode 20 after firing is formed on the raw sheet containing the calcined powder.
  • the electrode pattern may be formed by a conventional method, and a method of printing or applying a paste containing an electrode material is preferable in terms of cost.
  • powder (co-material) or glass frit having the same composition and crystal structure as the piezoelectric ceramics after firing is used. It may be contained in the paste.
  • a laminated piezoelectric element having a structure different from that shown in FIGS. 1 to 3 there is also an example in which internal electrodes are electrically connected to each other via through holes (vias) penetrating in the piezoelectric ceramic layer.
  • a through hole is formed in the obtained raw sheet by punching or irradiation with a laser beam prior to the formation of the electrode pattern, and before and after the formation of the electrode pattern. Then, the through hole is filled with the electrode material.
  • the filling method is not particularly limited, but a method of printing a paste containing an electrode material is preferable in terms of cost.
  • a predetermined number of raw sheets having an electrode pattern formed are laminated, and the sheets are adhered to each other to obtain a molded product.
  • Lamination and adhesion may be performed by a conventional method, and a method of thermocompression bonding the raw sheets to each other by the action of a binder is preferable in terms of cost.
  • the molded product obtained by the above procedure becomes the piezoelectric ceramics related to the first side surface after the binder is removed as needed and then fired.
  • the firing conditions may be appropriately set in consideration of the sinterability of the calcined powder and the durability of the electrode material when it is contained in the molded body.
  • the firing atmosphere is a reducing or inert atmosphere in order to prevent oxidation thereof. Examples of firing conditions for a molded product containing neither copper (Cu) nor nickel (Ni) as an electrode material include 1 hour to 5 hours at 900 ° C. to 1200 ° C. in an air atmosphere.
  • the firing temperature is preferably 1100 ° C.
  • the molded product may be divided into several blocks prior to firing.
  • the piezoelectric element according to the other aspect of the present invention (hereinafter, may be simply referred to as “second side surface”) is electrically connected to the piezoelectric ceramics according to the first aspect described above and the piezoelectric ceramics. It is equipped with an electrode. Since the second side surface is provided with the piezoelectric ceramics related to the first side surface, the piezoelectric element has a large mechanical quality coefficient Qm and generates less heat even when driven at a high speed and a large amplitude.
  • the material, shape and arrangement of the electrodes are not particularly limited as long as the desired voltage can be applied to the piezoelectric ceramics.
  • electrode materials include silver (Ag), copper (Cu), gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), and alloys thereof.
  • the shape and arrangement of the electrodes those covering almost the entire specific surface of the piezoelectric ceramics can be mentioned.
  • the piezoelectric element is a laminated piezoelectric element 100 having a layered structure of the piezoelectric ceramic layer 10 and the internal electrode 20 as shown in FIGS. 1 to 3, the piezoelectric ceramic portion exposed on the element surface is covered.
  • the connecting conductors 31 and 32 that cover the exposed portion of the internal electrode 20 and connect them every other layer are provided. You may.
  • the piezoelectric element according to the second side surface is manufactured by forming an electrode on the surface of the piezoelectric ceramics according to the first side surface and performing a polarization treatment. This manufacturing method will be described below.
  • a commonly used method such as a method of applying or printing a paste containing the electrode material on the surface of the piezoelectric ceramic and baking it, or a method of depositing the electrode material on the surface of the piezoelectric ceramic can be adopted.
  • the conditions of the polarization treatment are not particularly limited as long as the directions of spontaneous polarization can be aligned without causing damage such as cracks in the piezoelectric ceramics.
  • an electric field of 1 kV / mm to 5 kV / mm may be applied at a temperature of 100 ° C. to 180 ° C.
  • the ultrasonic vibrator according to still another aspect of the present invention (hereinafter, may be simply referred to as "third side surface”) is a pair of the piezoelectric element according to the second side surface and the piezoelectric element sandwiching the piezoelectric element from the uniaxial direction. It is equipped with a block body.
  • This ultrasonic oscillator is known as a Langevin type oscillator.
  • the Langevin type oscillator may be a so-called bolt-tightened Langevin oscillator in which a block body is bolted to the piezoelectric element and sandwiched and integrated.
  • the Langevin type vibrator operates so as to generate ultrasonic vibration by supplying electric energy to the piezoelectric element and transmit the ultrasonic vibration to the outside through the block body. Since the third side surface is provided with a piezoelectric element related to the second side surface, it becomes a vibrator capable of stable driving for a long period of time with less heat generation when driven at high speed and large amplitude.
  • the material of the block body used on the third side surface is not particularly limited as long as it can efficiently transmit the ultrasonic vibration generated from the piezoelectric element, and for example, titanium alloy, aluminum alloy, SUS or the like can be used.
  • Example 1 [Manufacturing of piezoelectric ceramics]
  • high-purity Pb 3 O 4 , ZrO 2 , TIO 2 , ZnO and Nb 2 O 5 powders were prepared, and each of the powders had a composition formula of Pb ⁇ (Zr 0.4029 Ti 0.3871 ) ( Weighed so as to obtain a calcined powder having a perovskite-type structure represented by Zn 1/3 Nb 2/3 ) 0.21 ⁇ O3 , and wet-mixed with a ball mill using zirconia balls. After mixing, the mixed powder from which the dispersion medium was removed was calcined in the air at 820 ° C.
  • Example 1 After crushing the obtained calcined powder, 0.5% by mass of high-purity MnCO 3 powder is mixed with the calcined powder, an acrylic binder is added, and uniaxial press molding is performed with a load of 2 tf. Then, a disk-shaped molded body having a diameter of 10 mm was obtained. The obtained molded product was fired in the air at 1100 ° C. for 2 hours to obtain the piezoelectric ceramics according to Example 1.
  • An electrode was formed by applying Ag paste to both sides of the above-mentioned disc-shaped piezoelectric ceramics, passing the paste through a belt furnace set at 800 ° C., and baking the paste.
  • the piezoelectric ceramics after electrode formation were polarized in silicon oil at 150 ° C. at an electric field strength of 2.2 kV / mm for 15 minutes to obtain a piezoelectric element for testing.
  • Examples 2 to 4 [Manufacturing of piezoelectric ceramics]
  • the amount of MnCO 3 powder to be mixed with the calcined powder was 1.0% by mass (Example 2), 1.5% by mass (Example 3) and 2.0% by mass (Example 3) with respect to the calcined powder.
  • the piezoelectric ceramics according to Examples 2, 3 and 4, respectively, were produced in the same manner as in Example 1 except that in Example 4).
  • Example 2 the Zn-containing oxide ratio was 0.7%.
  • Example 3 the avg was 3.3 ⁇ m, in Example 3, the Zn-containing oxide rate was 1.6% and the ravg was 4.5 ⁇ m, and in Example 4, the Zn-containing oxide rate was 1.3% and the ravg was 4.6 ⁇ m. became.
  • Example 1 (Manufacturing of piezoelectric ceramics]
  • the MnCO 3 powder mixed with the calcined powder in Example 1 was mixed at the same time as the starting material powder, and the MnCO 3 powder was not added to the calcined powder in the same manner as in Example 1. , The piezoelectric ceramics according to Comparative Example 1 were manufactured.
  • a piezoelectric element for testing was manufactured from the piezoelectric ceramics according to the comparative example by the same method as in Example 1, and the mechanical quality coefficient Qm thereof was measured and calculated. As a result, the mechanical quality coefficient Qm was 65.
  • the piezoelectric ceramics according to the examples in which the Zn-containing oxide ratio was 0.3% or more and the presence of the Zn-containing oxide was confirmed in addition to the compound having a perovskite-type structure were found. It can be seen that when a piezoelectric element is used, it exhibits a high mechanical quality coefficient Qm. From this result, the Zn-containing oxide ratio was set to 0.3% or more in the piezoelectric ceramics containing Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements and mainly containing a compound having a perovskite-type structure. By doing so, it can be said that a piezoelectric element having a high mechanical quality coefficient Qm can be formed.
  • the average particle size ravg is larger than that according to the comparative examples. Since it has been confirmed by previous studies that piezoelectric ceramics composed of large particles tend to have a high mechanical quality coefficient Qm, such a large average particle size ravg also has a mechanical quality coefficient Qm in the piezoelectric element. It is understood that it contributes to improvement.
  • piezoelectric ceramics capable of stably obtaining a piezoelectric element having a small mechanical loss when driven at a high speed and a large amplitude.
  • Such piezoelectric ceramics have higher performance and reliability because the amount of heat generated during driving is suppressed compared to conventional ones when an ultrasonic vibrator, piezoelectric transformer, etc. are formed and driven at high speed and large amplitude. It becomes. Therefore, the piezoelectric element provided with the piezoelectric ceramics according to the present invention can be suitably used for an ultrasonic vibrator, a piezoelectric transformer, or the like.

Abstract

A piezoelectric ceramic according to one aspect of the present invention comprises, as a main component, a compound containing Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements and having a Perovskite-based structure, wherein, in X-ray diffraction measurements using Cu-K α-rays, a total ratio (IZT + IZnO)/IP × 100) of a maximum peak intensity IZT expressed at 34.0°≦2θ≦ 35.0° and a maximum peak intensity IZnO expressed at 35.5° ≦ 2θ≦ 37.0° with respect to a maximum peak intensity IP expressed at 20.0° ≦ 2θ ≦ 40.0° is 0.3% or greater.

Description

圧電セラミックス、圧電素子及び超音波振動子Piezoelectric ceramics, piezoelectric elements and ultrasonic vibrators
　本発明は、圧電セラミックス、圧電素子及び超音波振動子に関する。 The present invention relates to piezoelectric ceramics, piezoelectric elements and ultrasonic vibrators.
　圧電素子は、機械的エネルギーを電気的エネルギーに変換する正圧電効果を利用して、センサ素子や発電素子等に用いられている。また、圧電素子は、電気的エネルギーを機械的エネルギーに変換する逆圧電効果を利用して、振動子、発音体、アクチュエータ、超音波モータ及びポンプ等にも用いられている。さらに、圧電素子は、正圧電効果と逆圧電効果との併用により、回路素子及び振動制御素子等にも用いられている。 Piezoelectric elements are used in sensor elements, power generation elements, etc. by utilizing the positive piezoelectric effect that converts mechanical energy into electrical energy. Piezoelectric elements are also used in vibrators, sounding bodies, actuators, ultrasonic motors, pumps, etc. by utilizing the inverse piezoelectric effect of converting electrical energy into mechanical energy. Further, the piezoelectric element is also used in a circuit element, a vibration control element, and the like by using the positive piezoelectric effect and the inverse piezoelectric effect in combination.
　圧電素子のうち、圧電トランス、振動子及び超音波モータ等については、共振点等の大振幅が生じる条件下で連続駆動されるため、素子自体が発熱しやすい。圧電素子の発熱は、圧電特性の劣化や喪失に繋がるため、これを抑制する必要がある。圧電素子の発熱は、駆動時に生じる機械的な損失と電気的な損失とに起因する。このため、前述のような圧電素子には、ハード系圧電材料あるいはハード材と称される、前述した両損失の小さい材料が用いられている。ハード系圧電材料においては、機械的な損失が小さいことの指標として機械的品質係数Ｑｍが高いことが、電気的な損失が小さいことの指標として誘電正接ｔａｎδが小さいことが、それぞれ重要となる。 Among the piezoelectric elements, the piezoelectric transformer, vibrator, ultrasonic motor, etc. are continuously driven under conditions where a large amplitude such as a resonance point is generated, so that the element itself tends to generate heat. Since the heat generated by the piezoelectric element leads to deterioration or loss of the piezoelectric characteristics, it is necessary to suppress this. The heat generated by the piezoelectric element is caused by mechanical loss and electrical loss that occur during driving. Therefore, as the piezoelectric element as described above, the above-mentioned material having both small losses, which is called a hard piezoelectric material or a hard material, is used. In the hard piezoelectric material, it is important that the mechanical quality coefficient Qm is high as an index of the small mechanical loss and that the dielectric loss tang tan δ is small as an index of the small electrical loss.
　このような低損失のハード系圧電材料としては、ペロブスカイト型構造を有するチタン酸ジルコン酸鉛（Ｐｂ（Ｚｒ，Ｔｉ）Ｏ３：ＰＺＴ）を基本組成とし、これに種々の元素を固溶させて低損失化したものが提案されている。 As such a low-loss hard piezoelectric material, lead zirconate titanate (Pb (Zr, Ti) O 3 : PZT) having a perovskite-type structure is used as a basic composition, and various elements are dissolved therein. The one with low loss has been proposed.
　例えば、機械的品質係数Ｑｍが高く、比較的低温での焼成が可能な圧電磁器組成物として、Ｐｂ、Ｚｎ、Ｎｂ、Ｔｉ、Ｚｒ及びＯを構成元素として含み、ペロブスカイト型構造を有する化合物を主成分とするものが知られている（特許文献１、２）。 For example, as a piezoelectric composition having a high mechanical quality coefficient Qm and capable of firing at a relatively low temperature, a compound containing Pb, Zn, Nb, Ti, Zr and O as constituent elements and having a perovskite-type structure is mainly used. Those used as ingredients are known (Patent Documents 1 and 2).
　また、ＰＺＴ系の圧電セラミックスの機械的品質係数Ｑｍを高める手段として、ドメインサイズが１００ｎｍ以下である結晶粒子の面積比率を３０％以上とすることも知られている（特許文献３）。 It is also known that the area ratio of crystal particles having a domain size of 100 nm or less is set to 30% or more as a means for increasing the mechanical quality coefficient Qm of PZT-based piezoelectric ceramics (Patent Document 3).
特公昭５４－１８４００号公報Special Publication No. 54-18400 特開２００１－１８１０３７号公報Japanese Unexamined Patent Publication No. 2001-181037 特開２０１７－９２２８０号公報JP-A-2017-92280
　特許文献１、２に記載された圧電磁器組成物によれば、高い機械的品質係数Ｑｍを有する圧電素子が得られることはあるものの、原料の配合割合及び焼成温度等の製造条件の僅かな変動により、得られる圧電素子における機械的品質係数Ｑｍが所期の値とならない場合があることが問題であった。 According to the pressure electromagnetic device compositions described in Patent Documents 1 and 2, although a piezoelectric element having a high mechanical quality coefficient Qm may be obtained, slight fluctuations in production conditions such as a blending ratio of raw materials and a firing temperature may occur. Therefore, there is a problem that the mechanical quality coefficient Qm in the obtained piezoelectric element may not be the desired value.
　また、特許文献３に記載された圧電セラミックスは、セラミックス粒子中のドメインサイズが小さいため、ドメイン同士の境界であるドメインウォールの数が多くなる。セラミックス粒子中のドメインウォールは、高速大振幅で圧電素子を駆動した場合に該粒子中を移動し、この移動により機械的損失が生じるとされている。このため、ドメインウォールを多数含む特許文献３に記載された圧電セラミックスは、これにより形成された圧電素子を高速大振幅で駆動した際に、機械的損失が大きくなることが懸念される。 Further, since the piezoelectric ceramics described in Patent Document 3 have a small domain size in the ceramic particles, the number of domain walls that are boundaries between domains increases. It is said that the domain wall in the ceramic particles moves in the particles when the piezoelectric element is driven at high speed and large amplitude, and this movement causes mechanical loss. Therefore, the piezoelectric ceramics described in Patent Document 3 including a large number of domain walls are concerned that the mechanical loss becomes large when the piezoelectric element formed by the piezoelectric ceramics is driven at high speed and large amplitude.
　そこで本発明は、高速大振幅で駆動した場合の機械的損失が小さい圧電素子を、安定して得ることが可能な圧電セラミックスを提供することを目的とする。 Therefore, an object of the present invention is to provide piezoelectric ceramics capable of stably obtaining a piezoelectric element having a small mechanical loss when driven at a high speed and a large amplitude.
　本発明者は、前記課題を解決するために種々の検討を行ったところ、圧電セラミックスを、ペロブスカイト構造を有する化合物に加えて、これとは結晶構造の異なるＺｎ含有酸化物を含むものとすることで、該課題を解決できることを見出し、本発明を完成するに至った。 The present inventor has conducted various studies to solve the above problems, and found that the piezoelectric ceramic contains a Zn-containing oxide having a crystal structure different from that of the compound having a perovskite structure. We have found that the problem can be solved and have completed the present invention.
　すなわち、前記課題を解決するための本発明の一側面は、構成元素としてＰｂ、Ｚｒ、Ｔｉ、Ｚｎ、Ｎｂ、Ｍｎ及びＯを含み、ペロブスカイト型構造を有する化合物を主成分とし、かつＣｕ－Ｋα線を用いたＸ線回折測定において、２０．０°≦２θ≦４０．０°に現れる最大ピーク強度ＩＰに対する、３４．０°≦２θ≦３５．０°に現れる最大ピーク強度ＩＺＴと３５．５°≦２θ≦３７．０°に現れる最大ピーク強度ＩＺｎＯとの合計の割合（（ＩＺＴ＋ＩＺｎＯ）／ＩＰ×１００）が、０．３％以上となる圧電セラミックスである。 That is, one aspect of the present invention for solving the above-mentioned problems is that a compound containing Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements and having a perovskite-type structure as a main component and Cu—Kα is used as a main component. In the X - ray diffraction measurement using a line, the maximum peak intensity I ZT and 35 appearing at 34.0 ° ≤ 2θ ≤ 35.0 ° with respect to the maximum peak intensity IP appearing at 20.0 ° ≤ 2θ ≤ 40.0 °. This is a piezoelectric ceramic in which the total ratio ((I ZT + I ZnO ) / IP × 100) with the maximum peak intensity I ZnO appearing in 5.5 ° ≦ 2θ ≦ 37.0 ° is 0.3% or more.
　また、本発明の他の一側面は、前述の圧電セラミックスと、該圧電セラミックスに電気的に接続された電極とを備える圧電素子である。 Further, another aspect of the present invention is a piezoelectric element including the above-mentioned piezoelectric ceramics and an electrode electrically connected to the piezoelectric ceramics.
　さらに、本発明の他の一側面は、前述の圧電素子と、該圧電素子を一軸方向から挟み込む一対のブロック体とを備える超音波振動子である。 Further, another aspect of the present invention is an ultrasonic vibrator including the above-mentioned piezoelectric element and a pair of block bodies that sandwich the piezoelectric element from the uniaxial direction.
　本発明によれば、高速大振幅で駆動した場合の機械的損失が小さい圧電素子を、安定して得ることが可能な圧電セラミックスを提供することができる。 According to the present invention, it is possible to provide piezoelectric ceramics capable of stably obtaining a piezoelectric element having a small mechanical loss when driven at a high speed and a large amplitude.
本発明の一側面に係る積層型圧電素子の構造を示す概略斜視図Schematic perspective view showing the structure of the laminated piezoelectric element according to one aspect of the present invention. 図１に示す積層型圧電素子の左側面図Left side view of the laminated piezoelectric element shown in FIG. 図１に示す積層型圧電素子のＡ－Ａ’断面図AA'cross-sectional view of the laminated piezoelectric element shown in FIG.
　以下、図面を参照しながら、本発明の構成及び作用効果について、技術的思想を交えて説明する。但し、作用機構については推定を含んでおり、その正否は、本発明を制限するものではない。なお、数値範囲の記載（２つの数値を「～」でつないだ記載）については、下限及び上限として記載された数値をも含む意味である。 Hereinafter, the configuration and action / effect of the present invention will be described with reference to the drawings, together with technical ideas. However, the mechanism of action includes estimation, and its correctness does not limit the present invention. The description of the numerical range (the description in which two numerical values are connected by "-") means that the numerical values described as the lower limit and the upper limit are also included.
　本明細書において、圧電素子の「高速大振幅での駆動」とは、共振周波数での駆動、又はレーザードップラー振動計にて測定した振動速度が０．６２ｍ／ｓ以上となる条件下での駆動をいう。 In the present specification, "driving at high speed and large amplitude" of the piezoelectric element means driving at a resonance frequency or driving under a condition that the vibration speed measured by a laser Doppler vibrometer is 0.62 m / s or more. To say.
［圧電セラミックス］
　本発明の一側面に係る圧電セラミックス（以下、単に「第１側面」と記載することがある。）は、構成元素としてＰｂ、Ｚｒ、Ｔｉ、Ｚｎ、Ｎｂ、Ｍｎ及びＯを含み、ペロブスカイト型構造を有する化合物を主成分とし、かつＣｕ－Ｋα線を用いたＸ線回折測定において、２０．０°≦２θ≦４０．０°に現れる最大ピーク強度ＩＰに対する、３４．０°≦２θ≦３５．０°に現れる最大ピーク強度ＩＺＴと３５．５°≦２θ≦３７．０°に現れる最大ピーク強度ＩＺｎＯとの合計の割合（｛（ＩＺＴ＋ＩＺｎＯ）／ＩＰ｝×１００）が、０．３％以上となることを特徴とする。 [Piezoelectric ceramics]
The piezoelectric ceramics according to one aspect of the present invention (hereinafter, may be simply referred to as “first aspect”) contain Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements, and have a perovskite-type structure. 34.0 ° ≤ 2θ ≤ 35 with respect to the maximum peak intensity IP appearing at 20.0 ° ≤ 2θ ≤ 40.0 ° in X - ray diffraction measurement using a compound having The total ratio ({(I ZT + I ZnO ) / IP} × 100) of the maximum peak intensity I ZT appearing at 0.0 ° and the maximum peak intensity I ZnO appearing at 35.5 ° ≤ 2θ ≤ 37.0 ° is , 0.3% or more.
　第１側面は、構成元素としてＰｂ、Ｚｒ、Ｔｉ、Ｚｎ、Ｎｂ、Ｍｎ及びＯを含むと共に、ペロブスカイト型構造を有する化合物を主成分とする。このことにより、ペロブスカイト構造を有する化合物が、Ｐｂ(Ｚｒ，Ｔｉ)Ｏ３－Ｐｂ(Ｚｎ，Ｎｂ)Ｏ３－Ｐｂ(Ｍｎ，Ｎｂ)Ｏ３を主体とするものとなり、圧電素子とした際に、印加電圧に対して大きな変位量が得られると共に、駆動時の機械的損失を抑えることができる。 The first aspect contains Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements and contains a compound having a perovskite-type structure as a main component. As a result, the compound having a perovskite structure is mainly composed of Pb (Zr, Ti) O 3 -Pb (Zn, Nb) O 3 -Pb (Mn, Nb) O 3 , and when it is used as a piezoelectric element. , A large amount of displacement can be obtained with respect to the applied voltage, and mechanical loss during driving can be suppressed.
　第１側面は、組成式が、下記式（１）にて表されるものであることが、より大きな変位量と、より低い機械的損失とを達成できる点で好ましい。 On the first aspect, it is preferable that the composition formula is represented by the following formula (1) in that a larger displacement amount and a lower mechanical loss can be achieved.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
　但し、式中のａ、ｂ、ｘ、ｙ及びｚはそれぞれ、０＜ａ≦０．１０、０．４５≦ｂ≦０．６０、０＜ｘ≦０．８５、０＜ｙ＜１．０、０＜ｚ≦０．１０及びｘ＋ｙ＋ｚ＝１．０を満たす実数である。 However, a, b, x, y and z in the equation are 0 <a≤0.10, 0.45≤b≤0.60, 0 <x≤0.85, 0 <y <1.0, respectively. , 0 <z≤0.10 and x + y + z = 1.0.
　ここで、第１側面が、構成元素としてＰｂ、Ｚｒ、Ｔｉ、Ｚｎ、Ｎｂ、Ｍｎ及びＯを含むこと、ペロブスカイト型構造を有する化合物を主成分とすること、並びに前記式（１）で表される組成を有することは、それぞれ以下の手順で確認する。まず、圧電セラミックスを粉砕して粉末状試料を調製する。圧電セラミックスが圧電素子を形成している場合には、電極や被覆等の圧電セラミックス以外の部分を除去した後、粉砕することが好ましいが、後述する積層型圧電素子等の、圧電セラミックス部分と他の部分との分離が困難であり、かつ圧電セラミックス部分の割合が他の部分に比べて高い圧電素子については、素子ごと粉砕して粉末状試料としてもよい。次いで、得られた粉末状試料について、Ｃｕ－Ｋα線を用いたＸ線回折装置(ＸＲＤ)で回折線プロファイルを測定し、ペロブスカイト構造由来のプロファイルにおける最強回折線強度に対する、他の構造由来の回折プロファイルにおける最強回折線強度の割合が１０％以下となったことをもって、圧電セラミックスがペロブスカイト型構造を有する化合物を主成分とするものと判断する。なお、圧電セラミックス部分を他の部分と分離することなく、圧電素子ごと粉砕して粉末状試料とした場合で、回折線プロファイル中に電極等の圧電セラミックス以外の部分に由来することが明らかなピークが観測された場合には、該ピークを除外して、前述した最強線強度の比較を行う。次いで、ペロブスカイト型構造を有する化合物を主成分とすることが確認された粉末状試料について、高周波誘導結合プラズマ（ＩＣＰ）発光分光分析、イオンクロマトグラフィー装置ないしは、蛍光Ｘ線（ＸＲＦ）分析装置によって組成分析を行う。そして、組成分析の結果から、酸素以外の各元素の有無を確認し、その存在が確認されたことをもって、圧電セラミックスが前記各元素を含むものと判断する。また、組成分析の結果から、酸素以外の元素の含有比率を算出し、該含有比率が前記式（１）における比率となっていることをもって、圧電セラミックスが前記式（１）で表される組成を有するものと判断する。 Here, the first aspect is represented by the above formula (1) that it contains Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements, and that the main component is a compound having a perovskite-type structure. It is confirmed by the following procedure that each of them has the same composition. First, the piezoelectric ceramics are crushed to prepare a powdery sample. When the piezoelectric ceramics form a piezoelectric element, it is preferable to remove parts other than the piezoelectric ceramics such as electrodes and coatings and then pulverize the parts. For a piezoelectric element that is difficult to separate from the portion and has a higher proportion of the piezoelectric ceramic portion than the other portion, the entire element may be crushed into a powder sample. Next, the diffraction line profile of the obtained powdered sample was measured by an X-ray diffractometer (XRD) using Cu—Kα rays, and diffraction from another structure with respect to the strongest diffraction line intensity in the profile derived from the perovskite structure. When the ratio of the strongest diffraction line intensity in the profile is 10% or less, it is judged that the piezoelectric ceramics are mainly composed of a compound having a perovskite type structure. When the piezoelectric ceramic part is crushed together with the piezoelectric element into a powder sample without being separated from other parts, it is clear that the peak is derived from a part other than the piezoelectric ceramic such as an electrode in the diffraction line profile. When is observed, the peak is excluded and the above-mentioned strongest line intensity is compared. Next, the powdery sample confirmed to contain a compound having a perovskite-type structure as a main component is composed by high-frequency inductively coupled plasma (ICP) emission spectroscopic analysis, ion chromatography device, or fluorescent X-ray (XRF) analysis device. Perform analysis. Then, from the result of the composition analysis, the presence or absence of each element other than oxygen is confirmed, and when the existence is confirmed, it is determined that the piezoelectric ceramic contains each of the above elements. Further, the composition of the piezoelectric ceramic is represented by the formula (1) when the content ratio of an element other than oxygen is calculated from the result of the composition analysis and the content ratio is the ratio in the formula (1). It is judged that it has.
　第１側面は、前述の各元素を構成元素として含有し、ペロブスカイト型構造を有する化合物を主成分とするものであれば、他の添加元素ないし化合物を含有するものであってもよい。添加元素の例としては、ＡＢＯ３で表されるペロブスカイト型構造において、Ａサイトに固溶するＣａ、Ｓｒ、Ｂａ、Ａｇ、Ｌａ、Ｃｅ及びＢｉ等、Ｂサイトに固溶するＭｇ、Ｆｅ、Ｃｏ、Ｎｉ、Ｔａ及びＷ等が挙げられる。化合物の例としては、焼結温度を下げるために添加した成分に由来する、ガラス質の粒界相等が挙げられる。 The first aspect may contain other additive elements or compounds as long as each of the above-mentioned elements is contained as a constituent element and the main component is a compound having a perovskite-type structure. Examples of additive elements include Ca, Sr, Ba, Ag, La, Ce and Bi, which are solid-solved in A-site in the perovskite-type structure represented by ABO 3 , and Mg, Fe, Co. , Ni, Ta, W and the like. Examples of the compound include glassy grain boundary phases derived from components added to lower the sintering temperature.
　第１側面は、Ｃｕ－Ｋα線を用いたＸ線回折測定において、２０．０°≦２θ≦４０．０°に現れる最大ピーク強度ＩＰに対する、３４．０°≦２θ≦３５．０°に現れる最大ピーク強度ＩＺＴと３５．５°≦２θ≦３７．０°に現れる最大ピーク強度ＩＺｎＯとの合計の割合（｛（ＩＺＴ＋ＩＺｎＯ）／ＩＰ｝×１００）（以下、「Ｚｎ含有酸化物率」と記載することがある）が、０．３％以上となる。このことにより、圧電素子とした際に、高い機械的品質係数Ｑｍを有するものとなる。 The first aspect is 34.0 ° ≤ 2θ ≤ 35.0 ° with respect to the maximum peak intensity IP appearing at 20.0 ° ≤ 2θ ≤ 40.0 ° in X - ray diffraction measurement using Cu-Kα rays. The total ratio of the maximum peak intensity I ZT that appears and the maximum peak intensity I ZnO that appears at 35.5 ° ≤ 2θ ≤ 37.0 ° ({(I ZT + I ZnO ) / IP} x 100) (hereinafter, "Zn" It may be described as "containing oxide ratio"), but it is 0.3% or more. As a result, when the piezoelectric element is used, it has a high mechanical quality coefficient Qm.
　第１側面において、Ｃｕ－Ｋα線を用いたＸ線回折測定を行った際に、２θが２０．０°～４０．０°の範囲に現れる最大ピーク強度ＩＰは、主成分であるペロブスカイト型構造を有する化合物に由来するものである。他方、２θが３４．０°～３５．０°の範囲に現れる最大ピーク強度ＩＺＴは、Ｚｎ及びＴｉを含む酸化物（ＺｎｐＴｉｑＯｒ（但し、ｐ、ｑ及びｒはそれぞれ実数））に由来するものであり、２θが３５．５°～３７．０°の範囲に現れる最大ピークＩＺｎＯは、酸化亜鉛（ＺｎＯ）に由来するものである。そうすると、ＩＰに対するＩＺＴとＩＺｎＯとの合計の割合であるＺｎ含有酸化物率の値が大きいことは、ペロブスカイト型構造とは異なる結晶構造を有するＺｎ含有酸化物の含有割合が相対的に高いことを意味する。そして、この割合が０．３％以上の場合に、機械的品質係数Ｑｍの高い圧電素子が得られるようになる。この理由は現時点では明確でないが、前記Ｚｎ含有酸化物の構成元素であるＺｎ及び／又はＴｉの起源はペロブスカイト型構造の化合物であることから、該Ｚｎ含有酸化物の生成によりペロブスカイト型構造中に格子欠陥が導入され、これにより形成される欠陥双極子の作用でドメインウォールの移動が抑制されることが、何らかの寄与をしているものと推測される。より高い機械的品質係数Ｑｍを得る点からは、Ｚｎ含有酸化物率は０．５％以上であることが好ましく、１．０％以上であることがより好ましい。Ｚｎ含有酸化物率の上限値は、第１側面がペロブスカイト型構造の化合物を主成分とするものであることから、前述のとおり１０％以下である。主成分であるペロブスカイト型構造の化合物の割合を高めて、印加電圧あたりの変位量が大きな圧電素子を得る点からは、Ｚｎ含有酸化物率は５％以下であることが好ましい。 In the first aspect, when X - ray diffraction measurement using Cu—Kα rays is performed, the maximum peak intensity IP in which 2θ appears in the range of 20.0 ° to 40.0 ° is the perovskite type, which is the main component. It is derived from a compound having a structure. On the other hand, the maximum peak intensity I ZT in which 2θ appears in the range of 34.0 ° to 35.0 ° is an oxide containing Zn and Ti (Zn p Ti q Or (however, p, q and r are real numbers, respectively)). ), And the maximum peak I ZnO in which 2θ appears in the range of 35.5 ° to 37.0 ° is derived from zinc oxide (ZnO). Then, the large value of the Zn - containing oxide ratio, which is the total ratio of I ZT and I ZnO to IP, means that the content ratio of Zn-containing oxide having a crystal structure different from that of the perovskite type structure is relatively high. It means high. Then, when this ratio is 0.3% or more, a piezoelectric element having a high mechanical quality coefficient Qm can be obtained. The reason for this is not clear at this time, but since the origin of Zn and / or Ti, which are constituent elements of the Zn-containing oxide, is a compound having a perovskite-type structure, the formation of the Zn-containing oxide causes the perovskite-type structure. It is presumed that the introduction of lattice defects and the suppression of the movement of the domain wall by the action of the defect dipoles formed by them contributes in some way. From the viewpoint of obtaining a higher mechanical quality coefficient Qm, the Zn-containing oxide ratio is preferably 0.5% or more, and more preferably 1.0% or more. The upper limit of the Zn-containing oxide ratio is 10% or less as described above because the first side surface is mainly composed of a compound having a perovskite-type structure. The Zn-containing oxide ratio is preferably 5% or less from the viewpoint of obtaining a piezoelectric element having a large displacement amount per applied voltage by increasing the proportion of the perovskite-type structure compound as the main component.
　ここで、Ｚｎ含有酸化物率は、以下の手順で算出する。まず、圧電セラミックスを、前述した方法で粉末状試料とし、そのＸＲＤプロファイルを測定する。次いで、得られた結果を、結晶構造解析用ソフトウェア（株式会社ライトストーン製、ＪＡＤＥ）を用いて解析し、２０．０°≦２θ≦４０．０°における最大ピーク強度ＩＰ、３４．０°≦２θ≦３５．０°における最大ピーク強度ＩＺＴ、及び３５．５°≦２θ≦３７．０°における最大ピークＩＺｎＯをそれぞれ求める。最後に、得られたＩＰ、ＩＺＴ、及びＩＺｎＯを用いて｛（ＩＺＴ＋ＩＺｎＯ）／ＩＰ｝×１００の値を算出し、これをＺｎ含有酸化物率とする。 Here, the Zn-containing oxide ratio is calculated by the following procedure. First, the piezoelectric ceramic is prepared as a powder sample by the method described above, and its XRD profile is measured. Next, the obtained results were analyzed using software for crystal structure analysis (JADE, manufactured by Lightstone Co., Ltd.), and the maximum peak intensity IP at 20.0 ° ≤ 2θ ≤ 40.0 °, 34.0 °. The maximum peak intensity I ZT at ≦ 2θ ≦ 35.0 ° and the maximum peak I ZnO at 35.5 ° ≦ 2θ ≦ 37.0 ° are obtained. Finally, using the obtained I P , I ZT , and I ZnO , a value of {(I ZT + I ZnO ) / I P } × 100 is calculated, and this is used as the Zn-containing oxide ratio.
　第１側面では、含有する粒子の平均粒径ｒａｖｇが２．５μｍ以上であることが好ましい。このことにより、圧電素子とした際に、粒子内に形成されるドメインが大きくなり、ドメインウォールの数が少なくなることで、高速大振幅で駆動した際の、ドメインウォールの移動に起因する機械的損失が抑制される。平均粒径ｒａｖｇは、２．７μｍ以上とすることがより好ましく、３．０μｍ以上とすることがさらに好ましく、３．５μｍ以上とすることが特に好ましい。平均粒径ｒａｖｇの上限値は特に限定されないが、粗大粒子による機械的強度の低下を抑制する点からは、１０μｍ以下とすることが好ましい。 On the first aspect, it is preferable that the average particle size ravg of the contained particles is 2.5 μm or more. As a result, when the piezoelectric element is used, the domain formed in the particle becomes large and the number of domain walls decreases, so that the mechanical wall is moved due to the movement of the domain wall when driven at high speed and large amplitude. Loss is suppressed. The average particle size ravg is more preferably 2.7 μm or more, further preferably 3.0 μm or more, and particularly preferably 3.5 μm or more. The upper limit of the average particle size ravg is not particularly limited, but is preferably 10 μm or less from the viewpoint of suppressing a decrease in mechanical strength due to coarse particles.
　ここで、第１側面における平均粒径ｒａｖｇは、以下の手順で決定する。
　まず、圧電セラミックスの表面に、導電性を付与するために白金を蒸着して測定用試料とする。圧電素子中の圧電セラミックスについては、素子表面に露出している部分がある場合は、該部分に対して白金を蒸着して測定用試料とする。圧電素子表面に圧電セラミックスが露出していない場合には、研磨、研削、切断又はエッチング等により圧電セラミックス部分を露出させた後、９００～９６０℃の温度で１５分～３０分程度の熱処理（サーマルエッチング）を行った後、白金を蒸着して測定用試料とする。次いで、測定用試料を、走査型電子顕微鏡（ＳＥＭ）にて観察し、視野中に６０～２００個程度の粒子が入る倍率にて、４～６枚の写真を撮影する。次いで、撮影した写真を画像処理することで、各粒子の円相当径を算出する。最後に、得られた個々の粒子の円相当径ｒｉ及びこれを算出した粒子の個数ｎから、下記式（２）により平均粒径ｒａｖｇを算出し、これを圧電セラミックスの平均粒径とする。 Here, the average particle size ravg in the first aspect is determined by the following procedure.
First, platinum is vapor-deposited on the surface of the piezoelectric ceramic to impart conductivity, and the sample is used as a measurement sample. Regarding the piezoelectric ceramics in the piezoelectric element, if there is an exposed portion on the surface of the element, platinum is vapor-deposited on the portion to prepare a sample for measurement. If the piezoelectric ceramics are not exposed on the surface of the piezoelectric element, the piezoelectric ceramics are exposed by polishing, grinding, cutting, etching, etc., and then heat-treated at a temperature of 900 to 960 ° C for about 15 to 30 minutes (thermal). After performing (etching), platinum is vapor-deposited to prepare a sample for measurement. Next, the measurement sample is observed with a scanning electron microscope (SEM), and 4 to 6 photographs are taken at a magnification of about 60 to 200 particles in the field of view. Next, the circle-equivalent diameter of each particle is calculated by performing image processing on the photograph taken. Finally, the average particle size ravg was calculated from the obtained circle-equivalent diameter ri of each particle and the calculated number of particles n by the following formula (2), and this was used as the average particle size of the piezoelectric ceramics. do.
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
［圧電セラミックスの製造方法］
　第１側面に係る圧電セラミックスは、例えば、Ｐｂ、Ｚｒ、Ｔｉ、Ｚｎ及びＮｂから選択される１種又は複数種の元素を含む化合物の粉末を混合し、該各元素を含む混合粉末を得ること、前記混合粉末を仮焼して仮焼粉を得ること、前記仮焼粉に対してＭｎを含む化合物を混合した後、所定形状に成形して成形体を得ること、及び前記成形体を焼成することを経て製造される。この製造方法について、以下に説明する。 [Manufacturing method of piezoelectric ceramics]
The piezoelectric ceramic according to the first aspect is obtained by mixing, for example, a powder of a compound containing one or more elements selected from Pb, Zr, Ti, Zn and Nb to obtain a mixed powder containing each element. , The mixed powder is calcined to obtain a calcined powder, a compound containing Mn is mixed with the calcined powder, and then molded into a predetermined shape to obtain a molded body, and the molded body is fired. Manufactured after doing. This manufacturing method will be described below.
　原料として使用する化合物の粉末は、焼成により第１側面に係る圧電セラミックスが得られるものであれば、組成及び粒度は限定されない。粉末を構成する化合物は、前述した元素以外の添加元素を含むものであってもよい。使用できる化合物の例としては、Ｐｂ含有化合物としてＰｂＯ及びＰｂ３Ｏ４等が、Ｚｒ含有化合物としてＺｒＯ２等が、Ｔｉ含有化合物としてＴｉＯ２等が、Ｚｎ含有化合物としてＺｎＯ等が、Ｎｂ含有化合物としてＮｂ２Ｏ５等が、それぞれ挙げられる。 The composition and particle size of the powder of the compound used as a raw material are not limited as long as the piezoelectric ceramics according to the first aspect can be obtained by firing. The compound constituting the powder may contain an additive element other than the above-mentioned elements. Examples of compounds that can be used include PbO and Pb 3O 4 as Pb-containing compounds, ZrO 2 and the like as Zr - containing compounds, TIO 2 and the like as Ti-containing compounds, ZnO and the like as Zn-containing compounds, and Nb-containing compounds. Examples include Nb 2 O 5 and the like.
　原料粉末の混合方法は、不純物の混入を防ぎつつ各粉末が均一に混合されるものであれば特に限定されず、乾式混合、湿式混合のいずれを採用してもよい。ボールミルを用いた湿式混合を採用する場合には、例えば８～２４時間程度混合すればよい。 The mixing method of the raw material powder is not particularly limited as long as each powder is uniformly mixed while preventing the mixing of impurities, and either dry mixing or wet mixing may be adopted. When wet mixing using a ball mill is adopted, it may be mixed for about 8 to 24 hours, for example.
　仮焼条件は、各原料が反応して上述した組成式で表されるペロブスカイト型化合物を主成分とする仮焼粉が得られるものであれば限定されず、例えば大気雰囲気中、７００℃～１０００℃で２時間～８時間とすればよい。焼成温度が低すぎたり、焼成時間が短すぎたりすると、未反応の原料や中間生成物が残存する虞がある。反対に、焼成温度が高すぎたり、焼成時間が長すぎたりすると、ＰｂやＺｎの揮発により所期の組成の化合物が得られない虞や、生成物が固結して解砕しにくくなることで生産性が低下する虞がある。 The calcination conditions are not limited as long as each raw material reacts to obtain a calcination powder containing a perovskite-type compound represented by the above-mentioned composition formula as a main component. For example, in an air atmosphere, 700 ° C. to 1000 ° C. The temperature may be 2 to 8 hours. If the firing temperature is too low or the firing time is too short, unreacted raw materials and intermediate products may remain. On the other hand, if the firing temperature is too high or the firing time is too long, there is a risk that a compound having the desired composition cannot be obtained due to volatilization of Pb and Zn, and the product will solidify and become difficult to crush. There is a risk that productivity will decrease.
　仮焼粉に混合するＭｎ含有化合物は、前述した原料粉末と同様に、焼成により第１側面に係る圧電セラミックスが得られるものであれば、組成及び粒度は限定されない。使用できる化合物の例としては、ＭｎＣＯ３等が挙げられる。また、仮焼粉とＭｎ含有化合物との混合方法としては、前述した原料粉末の混合方法と同様のものが採用できる。なお、Ｍｎ含有化合物は、前述の原料粉末と同時に混合してもよいが、仮焼粉に対して混合した方が、Ｚｎ含有酸化物の含有量の多い圧電セラミックスが得られやすいため、好ましい。 The composition and particle size of the Mn-containing compound to be mixed with the calcined powder are not limited as long as the piezoelectric ceramics according to the first aspect can be obtained by firing, as in the case of the raw material powder described above. Examples of compounds that can be used include MnCO 3 . Further, as a method for mixing the calcined powder and the Mn-containing compound, the same method as the above-mentioned mixing method for the raw material powder can be adopted. The Mn-containing compound may be mixed at the same time as the above-mentioned raw material powder, but it is preferable to mix the Mn-containing compound with the calcined powder because piezoelectric ceramics having a high Zn-containing oxide content can be easily obtained.
　Ｍｎ含有化合物と混合した仮焼粉を成形する方法としては、粉末の一軸加圧成形、粉末を含む坏土の押出成形及び粉末を分散したスラリーの鋳込成形等の、セラミックス粉末の成形に通常用いられる方法を採用することができる。 As a method for molding the calcined powder mixed with the Mn-containing compound, it is usually used for molding ceramic powder such as uniaxial pressure molding of powder, extrusion molding of clay containing powder, and casting molding of slurry in which powder is dispersed. The method used can be adopted.
　ここで、圧電セラミックスを、図１～３に示す積層型圧電素子１００の圧電セラミックス層１０として得る場合には、成形方法として以下のものを採用できる。 Here, when the piezoelectric ceramics are obtained as the piezoelectric ceramic layer 10 of the laminated piezoelectric element 100 shown in FIGS. 1 to 3, the following molding method can be adopted.
　まず、Ｍｎ含有化合物と混合した仮焼粉をバインダー等と混合し、スラリー又は坏土を形成した後、これをシート状に成形して仮焼粉を含む生シートを得る。シートの成形方法としては、ドクターブレード法、押出成形法等の慣用されている方法を採用できる。 First, the calcined powder mixed with the Mn-containing compound is mixed with a binder or the like to form a slurry or clay, and then this is molded into a sheet to obtain a raw sheet containing the calcined powder. As a sheet molding method, a commonly used method such as a doctor blade method or an extrusion molding method can be adopted.
　次いで、仮焼粉を含む生シート上に、焼成後に内部電極２０となる電極パターンを形成する。電極パターンは慣用されている方法で形成すれば良く、電極材料を含むペーストを印刷又は塗布する方法がコストの点で好ましい。印刷又は塗布により電極パターンを形成する際には、焼成後の圧電セラミックスへの付着強度を向上させるため、焼成後の圧電セラミックスと同様の組成及び結晶構造を有する粉末（共材）やガラスフリットをペースト中に含有させてもよい。 Next, an electrode pattern that becomes the internal electrode 20 after firing is formed on the raw sheet containing the calcined powder. The electrode pattern may be formed by a conventional method, and a method of printing or applying a paste containing an electrode material is preferable in terms of cost. When forming an electrode pattern by printing or coating, in order to improve the adhesion strength to the piezoelectric ceramics after firing, powder (co-material) or glass frit having the same composition and crystal structure as the piezoelectric ceramics after firing is used. It may be contained in the paste.
　なお、図１～３に示すものとは異なる構造を有する積層型圧電素子として、圧電セラミックス層内を貫通するスルーホール（ビア）を介して内部電極同士を電気的に接続したものも挙げられる。こうした構造の積層型圧電素子を製造する場合には、電極パターンの形成に先立ち、得られた生シートに、パンチングやレーザー光の照射等により貫通孔を形成すると共に、電極パターンの形成に前後して、該貫通孔に電極材料を充填する。充填方法は特に限定されないが、電極材料を含むペーストを印刷する方法が、コストの点で好ましい。 As a laminated piezoelectric element having a structure different from that shown in FIGS. 1 to 3, there is also an example in which internal electrodes are electrically connected to each other via through holes (vias) penetrating in the piezoelectric ceramic layer. In the case of manufacturing a laminated piezoelectric element having such a structure, a through hole is formed in the obtained raw sheet by punching or irradiation with a laser beam prior to the formation of the electrode pattern, and before and after the formation of the electrode pattern. Then, the through hole is filled with the electrode material. The filling method is not particularly limited, but a method of printing a paste containing an electrode material is preferable in terms of cost.
　最後に、電極パターンを形成した生シートを所定の枚数積層し、シート同士を接着して成形体を得る。積層及び接着は慣用されている方法で行えば良く、生シート同士をバインダーの作用で熱圧着する方法がコストの点で好ましい。 Finally, a predetermined number of raw sheets having an electrode pattern formed are laminated, and the sheets are adhered to each other to obtain a molded product. Lamination and adhesion may be performed by a conventional method, and a method of thermocompression bonding the raw sheets to each other by the action of a binder is preferable in terms of cost.
　以上の手順で得られた成形体は、必要に応じてバインダーが除去された後、焼成を経て第１側面に係る圧電セラミックスとなる。焼成の条件は、仮焼粉の焼結性、及び成形体中に電極材料が含まれる場合にはその耐久性等を考慮して、適宜設定すればよい。なお、電極材料として銅（Ｃｕ）又はニッケル（Ｎｉ）を含む成形体を焼成する場合には、その酸化を防止するために、焼成雰囲気を還元性ないし不活性雰囲気とすることが好ましい。電極材料として銅（Ｃｕ）又はニッケル（Ｎｉ）のいずれも含まない成形体の焼成条件の例としては、大気雰囲気中、９００℃～１２００℃で１時間～５時間が挙げられる。焼成温度が低すぎたり、焼成時間が短すぎたりすると、緻密化が不十分であることにより、所期の特性の圧電セラミックスが得られない虞がある。反対に、焼成温度が高すぎたり、焼成時間が長すぎたりすると、ＰｂやＺｎの揮発により組成ずれが生じる虞や、粗大粒子の生成により特性が低下する虞がある。また、成形体が電極材料を含む場合には、該電極材料の溶融や拡散により所期の特性の圧電セラミックスないし圧電素子が得られなくなる虞もある。焼成温度が高すぎることによるこうした不都合を避けると共に、電極材料に低融点の材料を使用して材料コストを低減する点からは、焼成温度を１１００℃以下とすることが好ましい。なお、１つの成形体から複数の圧電セラミックスないし圧電素子を得る場合には、焼成に先立って成形体を幾つかのブロックに分割してもよい。 The molded product obtained by the above procedure becomes the piezoelectric ceramics related to the first side surface after the binder is removed as needed and then fired. The firing conditions may be appropriately set in consideration of the sinterability of the calcined powder and the durability of the electrode material when it is contained in the molded body. When a molded body containing copper (Cu) or nickel (Ni) as an electrode material is fired, it is preferable that the firing atmosphere is a reducing or inert atmosphere in order to prevent oxidation thereof. Examples of firing conditions for a molded product containing neither copper (Cu) nor nickel (Ni) as an electrode material include 1 hour to 5 hours at 900 ° C. to 1200 ° C. in an air atmosphere. If the firing temperature is too low or the firing time is too short, there is a risk that piezoelectric ceramics with the desired characteristics cannot be obtained due to insufficient densification. On the other hand, if the firing temperature is too high or the firing time is too long, there is a risk that the composition may shift due to volatilization of Pb and Zn, and the characteristics may deteriorate due to the formation of coarse particles. Further, when the molded body contains an electrode material, there is a possibility that the piezoelectric ceramics or the piezoelectric element having the desired characteristics cannot be obtained due to melting or diffusion of the electrode material. The firing temperature is preferably 1100 ° C. or lower from the viewpoint of avoiding such inconvenience due to the firing temperature being too high and reducing the material cost by using a material having a low melting point as the electrode material. When a plurality of piezoelectric ceramics or piezoelectric elements are obtained from one molded product, the molded product may be divided into several blocks prior to firing.
［圧電素子］
　本発明の他の一側面に係る圧電素子（以下、単に「第２側面」と記載することがある）は、上述した第１側面に係る圧電セラミックスと、該圧電セラミックスに電気的に接続された電極とを備える。第２側面は、圧電セラミックスとして第１側面に係るものを備えることで、機械的品質係数Ｑｍが大きく、高速大振幅にて駆動した場合にも、発熱の少ない圧電素子となる。 [Piezoelectric element]
The piezoelectric element according to the other aspect of the present invention (hereinafter, may be simply referred to as “second side surface”) is electrically connected to the piezoelectric ceramics according to the first aspect described above and the piezoelectric ceramics. It is equipped with an electrode. Since the second side surface is provided with the piezoelectric ceramics related to the first side surface, the piezoelectric element has a large mechanical quality coefficient Qm and generates less heat even when driven at a high speed and a large amplitude.
　第２側面では、電極の材質、形状及び配置は、圧電セラミックスに対して所期の電圧を印加することができるものであれば特に限定されない。電極の材質の例としては、銀（Ａｇ）、銅（Ｃｕ）、金（Ａｕ）、白金（Ｐｔ）、パラジウム（Ｐｄ）及びニッケル（Ｎｉ）並びにこれらの合金等が挙げられる。また、電極の形状及び配置の例としては、圧電セラミックスの特定の面のほぼ全体を覆うものが挙げられる。加えて、圧電素子が、図１～３に示すような、圧電セラミックス層１０と内部電極２０との層状構造を有する積層型圧電素子１００である場合には、素子表面に露出する圧電セラミックス部分に電圧を印加したり、圧電セラミックス部分に発生した電圧を取り出したりするための外部電極３０に加えて、内部電極２０の露出部分を覆ってこれを１層おきに接続する接続導体３１、３２を備えてもよい。 On the second side surface, the material, shape and arrangement of the electrodes are not particularly limited as long as the desired voltage can be applied to the piezoelectric ceramics. Examples of electrode materials include silver (Ag), copper (Cu), gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), and alloys thereof. Further, as an example of the shape and arrangement of the electrodes, those covering almost the entire specific surface of the piezoelectric ceramics can be mentioned. In addition, when the piezoelectric element is a laminated piezoelectric element 100 having a layered structure of the piezoelectric ceramic layer 10 and the internal electrode 20 as shown in FIGS. 1 to 3, the piezoelectric ceramic portion exposed on the element surface is covered. In addition to the external electrode 30 for applying a voltage and extracting the voltage generated in the piezoelectric ceramics portion, the connecting conductors 31 and 32 that cover the exposed portion of the internal electrode 20 and connect them every other layer are provided. You may.
［圧電素子の製造方法］
　第２側面に係る圧電素子は、第１側面に係る圧電セラミックスの表面に電極を形成し、分極処理することで製造される。この製造方法について、以下に説明する。 [Manufacturing method of piezoelectric element]
The piezoelectric element according to the second side surface is manufactured by forming an electrode on the surface of the piezoelectric ceramics according to the first side surface and performing a polarization treatment. This manufacturing method will be described below.
　電極の形成には、電極材料を含むペーストを圧電セラミックス表面に塗布ないし印刷して焼き付ける方法や、圧電セラミックス表面に電極材料を蒸着する方法等の、慣用されている方法を採用できる。 For the formation of the electrode, a commonly used method such as a method of applying or printing a paste containing the electrode material on the surface of the piezoelectric ceramic and baking it, or a method of depositing the electrode material on the surface of the piezoelectric ceramic can be adopted.
　分極処理の条件は、圧電セラミックスに亀裂等の損傷を生じることなく自発分極の向きを揃えられるものであれば特に限定されない。一例として、１００℃～１８０℃の温度にて、１ｋＶ／ｍｍ～５ｋＶ／ｍｍの電界を印加することが挙げられる。 The conditions of the polarization treatment are not particularly limited as long as the directions of spontaneous polarization can be aligned without causing damage such as cracks in the piezoelectric ceramics. As an example, an electric field of 1 kV / mm to 5 kV / mm may be applied at a temperature of 100 ° C. to 180 ° C.
［超音波振動子］
　本発明のさらに他の一側面に係る超音波振動子（以下、単に「第３側面」と記載することがある）は、第２側面に係る圧電素子と、該圧電素子を一軸方向から挟み込む一対のブロック体とを備える。この超音波振動子は、ランジュバン型振動子として知られている。ランジュバン型振動子は、圧電素子に対してブロック体をボルトで締め付けて挟み込んで一体化した、いわゆるボルト締めランジュバン振動子であってもよい。ランジュバン型振動子は、圧電素子に電気エネルギーを供給することで超音波振動を発生させ、該超音波振動を、前記ブロック体を介して外部に伝達するように作動する。第３側面は、圧電素子として第２側面に係るものを備えることで、高速大振幅にて駆動した場合の発熱が少なく、長時間にわたって安定した駆動が可能な振動子となる。 [Ultrasonic oscillator]
The ultrasonic vibrator according to still another aspect of the present invention (hereinafter, may be simply referred to as "third side surface") is a pair of the piezoelectric element according to the second side surface and the piezoelectric element sandwiching the piezoelectric element from the uniaxial direction. It is equipped with a block body. This ultrasonic oscillator is known as a Langevin type oscillator. The Langevin type oscillator may be a so-called bolt-tightened Langevin oscillator in which a block body is bolted to the piezoelectric element and sandwiched and integrated. The Langevin type vibrator operates so as to generate ultrasonic vibration by supplying electric energy to the piezoelectric element and transmit the ultrasonic vibration to the outside through the block body. Since the third side surface is provided with a piezoelectric element related to the second side surface, it becomes a vibrator capable of stable driving for a long period of time with less heat generation when driven at high speed and large amplitude.
　第３側面で使用するブロック体の材質は、圧電素子から発生する超音波振動を効率的に伝達可能なものであれば特に限定されず、例えばチタン合金、アルミニウム合金又はＳＵＳ等が使用できる。 The material of the block body used on the third side surface is not particularly limited as long as it can efficiently transmit the ultrasonic vibration generated from the piezoelectric element, and for example, titanium alloy, aluminum alloy, SUS or the like can be used.
　以下、実施例により本発明をさらに具体的に説明するが、本発明は該実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples.
（実施例１）
［圧電セラミックスの製造］
　出発原料として、高純度のＰｂ３Ｏ４、ＺｒＯ２、ＴｉＯ２、ＺｎＯ及びＮｂ２Ｏ５粉末を準備し、該各粉末を、組成式がＰｂ｛（Ｚｒ０．４０２９Ｔｉ０．３８７１）（Ｚｎ１／３Ｎｂ２／３）０．２１｝Ｏ３で表される、ペロブスカイト型構造を有する仮焼粉が得られるように秤量し、ジルコニアボールを用いたボールミルにて湿式混合した。混合後、分散媒を除去した混合粉末を、大気中、８２０℃にて３時間仮焼して、仮焼粉を得た。得られた仮焼粉を解砕した後、該仮焼粉に対して、高純度のＭｎＣＯ３粉末を０．５質量％混合すると共に、アクリル系バインダーを添加し、２ｔｆの荷重で一軸プレス成形して、直径１０ｍｍの円板状成形体を得た。得られた成形体を、大気中、１１００℃で２時間焼成し、実施例１に係る圧電セラミックスを得た。 (Example 1)
[Manufacturing of piezoelectric ceramics]
As a starting material, high-purity Pb 3 O 4 , ZrO 2 , TIO 2 , ZnO and Nb 2 O 5 powders were prepared, and each of the powders had a composition formula of Pb {(Zr 0.4029 Ti 0.3871 ) ( Weighed so as to obtain a calcined powder having a perovskite-type structure represented by Zn 1/3 Nb 2/3 ) 0.21 } O3 , and wet-mixed with a ball mill using zirconia balls. After mixing, the mixed powder from which the dispersion medium was removed was calcined in the air at 820 ° C. for 3 hours to obtain a calcined powder. After crushing the obtained calcined powder, 0.5% by mass of high-purity MnCO 3 powder is mixed with the calcined powder, an acrylic binder is added, and uniaxial press molding is performed with a load of 2 tf. Then, a disk-shaped molded body having a diameter of 10 mm was obtained. The obtained molded product was fired in the air at 1100 ° C. for 2 hours to obtain the piezoelectric ceramics according to Example 1.
［圧電セラミックスのＺｎ含有酸化物率測定］
　得られた圧電セラミックスについて、Ｚｎ含有酸化物率を、上述した方法で測定・算出したところ、０．３％となった。 [Measurement of Zn-containing oxide content of piezoelectric ceramics]
When the Zn-containing oxide ratio of the obtained piezoelectric ceramic was measured and calculated by the method described above, it was 0.3%.
［圧電セラミックスの平均粒径測定］
　得られた圧電セラミックスについて、平均粒径ｒａｖｇを、上述した方法で決定したところ、ｒａｖｇ＝２．７μｍとなった。 [Measurement of average particle size of piezoelectric ceramics]
When the average particle size ravg of the obtained piezoelectric ceramics was determined by the method described above, ravg = 2.7 μm.
［試験用圧電素子の製造］
　前述した円板状の圧電セラミックスの両面全体にＡｇペーストを塗布した後、８００℃に設定したベルト炉内を通過させて焼き付けることで電極を形成した。
　電極形成後の圧電セラミックスを、１５０℃のシリコンオイル中で、２．２ｋＶ／ｍｍの電界強度で１５分間分極処理して試験用圧電素子を得た。 [Manufacturing of piezoelectric elements for testing]
An electrode was formed by applying Ag paste to both sides of the above-mentioned disc-shaped piezoelectric ceramics, passing the paste through a belt furnace set at 800 ° C., and baking the paste.
The piezoelectric ceramics after electrode formation were polarized in silicon oil at 150 ° C. at an electric field strength of 2.2 kV / mm for 15 minutes to obtain a piezoelectric element for testing.
［試験用圧電素子の機械的品質係数Ｑｍ測定］
　分極後、２４時間経過した試験用圧電素子について、インピーダンスアナライザーを用いて、周波数とインピーダンスとの関係を測定し、共振－反共振法により機械的品質係数Ｑｍを算出した。測定の結果、機械的品質係数Ｑｍは１２６９であった。 [Measurement of mechanical quality coefficient Qm of test piezoelectric element]
For the test piezoelectric element 24 hours after polarization, the relationship between frequency and impedance was measured using an impedance analyzer, and the mechanical quality coefficient Qm was calculated by the resonance-antiresonance method. As a result of the measurement, the mechanical quality coefficient Qm was 1269.
（実施例２から４）
［圧電セラミックスの製造］
　仮焼粉に対して混合するＭｎＣＯ３粉末の量を、該仮焼粉に対して１．０質量％（実施例２）、１．５質量％（実施例３）及び２．０質量％（実施例４）とした以外は実施例１と同様の方法で、実施例２、３及び４に係る圧電セラミックスをそれぞれ製造した。 (Examples 2 to 4)
[Manufacturing of piezoelectric ceramics]
The amount of MnCO 3 powder to be mixed with the calcined powder was 1.0% by mass (Example 2), 1.5% by mass (Example 3) and 2.0% by mass (Example 3) with respect to the calcined powder. The piezoelectric ceramics according to Examples 2, 3 and 4, respectively, were produced in the same manner as in Example 1 except that in Example 4).
［圧電セラミックスのＺｎ含有酸化物率及び平均粒径測定］
　得られた圧電セラミックスについて、Ｚｎ含有酸化物率及び平均粒径ｒａｖｇを、実施例１と同様の方法で測定・算出したところ、実施例２ではＺｎ含有酸化物率が０．７％でｒａｖｇが３．３μｍ、実施例３ではＺｎ含有酸化物率が１．６％でｒａｖｇが４．５μｍ、実施例４ではＺｎ含有酸化物率が１．３％でｒａｖｇが４．６μｍとなった。 [Measurement of Zn-containing oxide content and average particle size of piezoelectric ceramics]
With respect to the obtained piezoelectric ceramics, the Zn-containing oxide ratio and the average particle size ravg were measured and calculated by the same method as in Example 1. In Example 2, the Zn-containing oxide ratio was 0.7%. In Example 3, the avg was 3.3 μm, in Example 3, the Zn-containing oxide rate was 1.6% and the ravg was 4.5 μm, and in Example 4, the Zn-containing oxide rate was 1.3% and the ravg was 4.6 μm. became.
［試験用圧電素子の製造及び機械的品質係数Ｑｍ測定］
　各実施例に係る圧電セラミックスから、実施例１と同様の方法で試験用圧電素子を製造し、その機械的品質係数Ｑｍを測定・算出した。その結果、機械的品質係数Ｑｍは、実施例２では１９５４、実施例３では２１１０、実施例４では８３４であった。 [Manufacturing of test piezoelectric element and measurement of mechanical quality coefficient Qm]
From the piezoelectric ceramics according to each example, a piezoelectric element for testing was manufactured by the same method as in Example 1, and the mechanical quality coefficient Qm thereof was measured and calculated. As a result, the mechanical quality coefficient Qm was 1954 in Example 2, 2110 in Example 3, and 834 in Example 4.
（比較例１）
［圧電セラミックスの製造］
　実施例１にて仮焼粉に対して混合したＭｎＣＯ３粉末を、出発原料の粉末と同時に混合し、仮焼粉に対するＭｎＣＯ３粉末の添加を行わなかった以外は実施例１と同様の方法で、比較例１に係る圧電セラミックスを製造した。 (Comparative Example 1)
[Manufacturing of piezoelectric ceramics]
The MnCO 3 powder mixed with the calcined powder in Example 1 was mixed at the same time as the starting material powder, and the MnCO 3 powder was not added to the calcined powder in the same manner as in Example 1. , The piezoelectric ceramics according to Comparative Example 1 were manufactured.
［圧電セラミックスのＺｎ含有酸化物率及び平均粒径測定］
　得られた圧電セラミックスについて、Ｚｎ含有酸化物率を、実施例１と同様の方法で測定・算出したところ、ＸＲＤプロファイルにて３４．０°≦２θ≦３５．０°、及び３５．５°≦２θ≦３７．０°の各範囲にピークは観測されず、Ｚｎ含有酸化物率は０％となった。また、得られた圧電セラミックスについて、平均粒径ｒａｖｇを、実施例１と同様の方法で測定・算出したところ、２．３μｍとなった。 [Measurement of Zn-containing oxide content and average particle size of piezoelectric ceramics]
When the Zn-containing oxide ratio of the obtained piezoelectric ceramics was measured and calculated by the same method as in Example 1, 34.0 ° ≤ 2θ ≤ 35.0 ° and 35.5 ° ≤ in the XRD profile. No peak was observed in each range of 2θ≤37.0 °, and the Zn-containing oxide ratio was 0%. Further, when the average particle size ravg of the obtained piezoelectric ceramics was measured and calculated by the same method as in Example 1, it was 2.3 μm.
［試験用圧電素子の製造及び機械的品質係数Ｑｍ測定］
　比較例に係る圧電セラミックスから、実施例１と同様の方法で試験用圧電素子を製造し、その機械的品質係数Ｑｍを測定・算出した。その結果、機械的品質係数Ｑｍは６５であった。 [Manufacturing of test piezoelectric element and measurement of mechanical quality coefficient Qm]
A piezoelectric element for testing was manufactured from the piezoelectric ceramics according to the comparative example by the same method as in Example 1, and the mechanical quality coefficient Qm thereof was measured and calculated. As a result, the mechanical quality coefficient Qm was 65.
　実施例及び比較例の結果をまとめて表１に示す。 Table 1 summarizes the results of Examples and Comparative Examples.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　実施例と比較例とを対比すると、Ｚｎ含有酸化物率が０．３％以上であり、ペロブスカイト型構造の化合物に加えてＺｎ含有酸化物の存在が確認された実施例に係る圧電セラミックスは、圧電素子とした際に、高い機械的品質係数Ｑｍを示すことが判る。この結果から、構成元素としてＰｂ、Ｚｒ、Ｔｉ、Ｚｎ、Ｎｂ、Ｍｎ及びＯを含み、ペロブスカイト型構造を有する化合物を主成分とする圧電セラミックスにおいて、Ｚｎ含有酸化物率を０．３％以上とすることで、機械的品質係数Ｑｍの高い圧電素子が形成できるといえる。また、実施例に係る圧電セラミックスにおいては、平均粒径ｒａｖｇが、比較例に係るものよりも大きくなっていることも判る。従前の検討により、大きな粒子で構成された圧電セラミックスは、高い機械的品質係数Ｑｍを有する傾向が確認されていることから、こうした大きな平均粒径ｒａｖｇも、圧電素子における機械的品質係数Ｑｍの向上に寄与していると解される。 Comparing the examples and the comparative examples, the piezoelectric ceramics according to the examples in which the Zn-containing oxide ratio was 0.3% or more and the presence of the Zn-containing oxide was confirmed in addition to the compound having a perovskite-type structure were found. It can be seen that when a piezoelectric element is used, it exhibits a high mechanical quality coefficient Qm. From this result, the Zn-containing oxide ratio was set to 0.3% or more in the piezoelectric ceramics containing Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements and mainly containing a compound having a perovskite-type structure. By doing so, it can be said that a piezoelectric element having a high mechanical quality coefficient Qm can be formed. It can also be seen that in the piezoelectric ceramics according to the examples, the average particle size ravg is larger than that according to the comparative examples. Since it has been confirmed by previous studies that piezoelectric ceramics composed of large particles tend to have a high mechanical quality coefficient Qm, such a large average particle size ravg also has a mechanical quality coefficient Qm in the piezoelectric element. It is understood that it contributes to improvement.
　本発明によれば、高速大振幅で駆動した場合の機械的損失が小さい圧電素子を、安定して得ることが可能な圧電セラミックスを提供することができる。このような圧電セラミックスは、超音波振動子や圧電トランス等を形成して高速大振幅で駆動した際に、駆動中の発熱量が従来のものよりも抑えられ、高性能で信頼性の高いものとなる。このため、本発明に係る圧電セラミックスを備える圧電素子は、超音波振動子や圧電トランス等に好適に用いることができる。 According to the present invention, it is possible to provide piezoelectric ceramics capable of stably obtaining a piezoelectric element having a small mechanical loss when driven at a high speed and a large amplitude. Such piezoelectric ceramics have higher performance and reliability because the amount of heat generated during driving is suppressed compared to conventional ones when an ultrasonic vibrator, piezoelectric transformer, etc. are formed and driven at high speed and large amplitude. It becomes. Therefore, the piezoelectric element provided with the piezoelectric ceramics according to the present invention can be suitably used for an ultrasonic vibrator, a piezoelectric transformer, or the like.
１００　　　積層型圧電素子
１０　　　　圧電セラミックス層
２０　　　　内部電極
３０　　　　外部電極
３１、３２　接続導体 100 Laminated piezoelectric element 10 Piezoelectric ceramic layer 20 Internal electrode 30 External electrode 31, 32 Connection conductor

Claims (5)

  1. 　構成元素としてＰｂ、Ｚｒ、Ｔｉ、Ｚｎ、Ｎｂ、Ｍｎ及びＯを含み、
    　ペロブスカイト型構造を有する化合物を主成分とし、かつ
    　Ｃｕ－Ｋα線を用いたＸ線回折測定において、２０．０°≦２θ≦４０．０°に現れる最大ピーク強度ＩＰに対する、３４．０°≦２θ≦３５．０°に現れる最大ピーク強度ＩＺＴと３５．５°≦２θ≦３７．０°に現れる最大ピーク強度ＩＺｎＯとの合計の割合（（ＩＺＴ＋ＩＺｎＯ）／ＩＰ×１００）が、０．３％以上となる
    圧電セラミックス。     Containing Pb, Zr, Ti, Zn, Nb, Mn and O as constituent elements,
    In X - ray diffraction measurement using a compound having a perovskite-type structure as a main component and using Cu—Kα rays, 34.0 ° ≦ with respect to the maximum peak intensity IP appearing at 20.0 ° ≦ 2θ ≦ 40.0 °. The total ratio of the maximum peak intensity I ZT appearing at 2θ ≤ 35.0 ° and the maximum peak intensity I ZnO appearing at 35.5 ° ≤ 2θ ≤ 37.0 ° ((I ZT + I ZnO ) / IP × 100) However, piezoelectric ceramics with 0.3% or more.
  2. 　含有する粒子の平均粒径ｒａｖｇが２．５μｍ以上である、請求項１に記載の圧電セラミックス。 The piezoelectric ceramic according to claim 1, wherein the average particle size ravg of the contained particles is 2.5 μm or more.
  3. 　組成式が、下記式（１）にて表される、請求項１又は２に記載の圧電セラミックス。
    Figure JPOXMLDOC01-appb-C000001
     （但し、式中のａ、ｂ、ｘ、ｙ及びｚはそれぞれ、０＜ａ≦０．１０、０．４５≦ｂ≦０．６０、０＜ｘ≦０．８５、０＜ｙ＜１．０、０＜ｚ≦０．１０及びｘ＋ｙ＋ｚ＝１．０を満たす実数である。）     The piezoelectric ceramic according to claim 1 or 2, wherein the composition formula is represented by the following formula (1).
    Figure JPOXMLDOC01-appb-C000001
     (However, a, b, x, y and z in the equation are 0 <a≤0.10, 0.45≤b≤0.60, 0 <x≤0.85, 0 <y <1. It is a real number that satisfies 0,0 <z≤0.10 and x + y + z = 1.0.)
  4. 　請求項１から３のいずれか１項に記載の圧電セラミックスと、該圧電セラミックスに電気的に接続された電極とを備える圧電素子。 A piezoelectric element comprising the piezoelectric ceramic according to any one of claims 1 to 3 and an electrode electrically connected to the piezoelectric ceramic.
  5. 　請求項４に記載の圧電素子と、該圧電素子を一軸方向から挟み込む一対のブロック体とを備える超音波振動子。 An ultrasonic vibrator including the piezoelectric element according to claim 4 and a pair of blocks that sandwich the piezoelectric element from a uniaxial direction.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001253773A (en) * 2000-01-07 2001-09-18 Tdk Corp Piezoelectric porcelain and piezoelectric device
JP2006193415A (en) * 2004-12-17 2006-07-27 Tdk Corp Piezoelectric ceramic and piezoelectric element
JP2007067152A (en) * 2005-08-31 2007-03-15 Tdk Corp Method of manufacturing laminated piezoelectric element
JP2017183542A (en) * 2016-03-30 2017-10-05 日本碍子株式会社 Piezoelectric element

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001253773A (en) * 2000-01-07 2001-09-18 Tdk Corp Piezoelectric porcelain and piezoelectric device
JP2006193415A (en) * 2004-12-17 2006-07-27 Tdk Corp Piezoelectric ceramic and piezoelectric element
JP2007067152A (en) * 2005-08-31 2007-03-15 Tdk Corp Method of manufacturing laminated piezoelectric element
JP2017183542A (en) * 2016-03-30 2017-10-05 日本碍子株式会社 Piezoelectric element

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