WO2023063007A1 - Élément piézoélectrique multicouche - Google Patents

Élément piézoélectrique multicouche Download PDF

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WO2023063007A1
WO2023063007A1 PCT/JP2022/034339 JP2022034339W WO2023063007A1 WO 2023063007 A1 WO2023063007 A1 WO 2023063007A1 JP 2022034339 W JP2022034339 W JP 2022034339W WO 2023063007 A1 WO2023063007 A1 WO 2023063007A1
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piezoelectric element
internal electrode
piezoelectric ceramic
mol
laminated piezoelectric
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PCT/JP2022/034339
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English (en)
Japanese (ja)
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亮 伊藤
隆幸 後藤
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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
    • C04B35/495—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 vanadium, niobium, tantalum, molybdenum or tungsten oxides or solid solutions thereof with other oxides, e.g. vanadates, niobates, tantalates, molybdates or tungstates
    • 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
    • H10N30/06—Forming electrodes or interconnections, e.g. leads or terminals
    • 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 laminated piezoelectric elements.
  • a piezoelectric element is an electronic component with a structure in which a piezoelectric ceramic (piezoelectric ceramic) is sandwiched between a pair of electrodes.
  • piezoelectricity is a property capable of mutually converting electrical energy and mechanical energy.
  • Piezoelectric elements use the aforementioned properties of piezoelectric ceramics to convert the voltage applied between a pair of electrodes into mechanical energy such as pressure or vibration, thereby moving other objects or moving itself. can do.
  • piezoelectric elements can convert mechanical energy such as vibration and pressure into electrical energy, and extract the electrical energy as voltage between a pair of electrodes.
  • the structure of the piezoelectric element in addition to the one in which electrodes are formed only on the surface of the piezoelectric ceramic, the one called laminated piezoelectric element in which multiple piezoelectric ceramic layers and internal electrode layers are alternately laminated is known.
  • Laminated piezoelectric elements can be used, for example, as actuators because they can provide a large displacement in the lamination direction of the piezoelectric ceramic layers.
  • Laminated piezoelectric elements are typically manufactured by simultaneously firing piezoelectric ceramic layers and internal electrode layers.
  • piezoelectric ceramics constituting such piezoelectric elements those mainly composed of lead zirconate titanate (Pb(Zr, Ti)O 3 , PZT) and their solid solutions are widely used. Since PZT-based piezoelectric ceramics have a high Curie temperature, it is possible to obtain a piezoelectric element that can be used even in a high-temperature environment. It has the advantage that a piezoelectric element that can be converted efficiently can be obtained. Moreover, by selecting an appropriate composition, firing can be performed at a temperature below 1000° C., which has the advantage of reducing the manufacturing cost of the piezoelectric element.
  • PZT-based piezoelectric ceramics have a high Curie temperature, it is possible to obtain a piezoelectric element that can be used even in a high-temperature environment. It has the advantage that a piezoelectric element that can be converted efficiently can be obtained. Moreover, by selecting an appropriate composition, firing can be performed at a temperature below 1000° C., which has the advantage
  • the internal electrodes co-fired with the piezoelectric ceramics are made of a low-melting-point material that contains a large proportion of silver, in other words, contains a small proportion of expensive materials such as platinum and palladium. Being able to use it will bring significant cost savings.
  • PZT-based piezoelectric ceramics contain lead, which is a hazardous substance, which is regarded as a problem.
  • Various compositions have been reported, such as layered compound systems and tungsten bronze systems.
  • alkaline niobate-based piezoelectric ceramics have a high Curie point and a relatively large electromechanical coupling coefficient, and are therefore attracting attention as alternatives to PZT-based ceramics (Patent Document 1).
  • Patent Document 2 it is reported that by setting the composition of alkaline niobate-based piezoelectric ceramics to contain an alkaline earth metal and silver, it was possible to sinter integrally with internal electrodes of Ag0.7Pd0.3. It is In addition, Patent Document 2 reports that the obtained laminated piezoelectric element exhibited high electrical resistivity and exhibited a large amount of displacement when a voltage was applied.
  • Patent Document 3 a non-conductive portion composed of a ceramic portion filled with ceramic powder and a void portion is formed at a specific ratio in an internal electrode layer of a laminated piezoelectric element, thereby preventing displacement by the internal electrode layer. reported to be suppressed.
  • Li 2 O and SiO 2 which are components that contribute to improving the sinterability
  • MnO which is a component that contributes to improving the electrical resistance
  • Li3NbO4 which has conductivity
  • lithium manganate which has a lower electrical resistivity than alkali niobates
  • the laminated piezoelectric element described in Patent Document 2 exhibits a large amount of displacement when a voltage is applied. may restrain the displacement of the piezoelectric ceramic layer.
  • Patent Document 3 does not describe prevention of shortening of the life of the piezoelectric element due to deterioration of electrical insulation during use.
  • an object of the present invention is to provide a multilayer piezoelectric element that does not contain lead as a constituent component, has a small decrease in electrical insulation during use, and has a large amount of displacement when a voltage is applied.
  • the laminated piezoelectric element is composed of a piezoelectric ceramic layer containing alkali niobate as a main component and a conductive portion containing silver as a main component. and having an internal electrode layer containing lithium manganate in at least a part of the gap where the conductive portion does not exist. reached.
  • one aspect of the present invention for solving the above problems is a piezoelectric ceramic layer mainly composed of alkali niobate having a perovskite structure, and a piezoelectric ceramic layer disposed between the piezoelectric ceramic layers and having a silver content of 50 mass. % or more, the area percentage (R 1 ) occupied by the conductive part is 75% or more and 95% or less, and the gap part where the conductive part does not exist is the average area percentage (R 2 ) is 5% or less, and an internal electrode layer containing lithium manganate is provided in at least one of the gaps.
  • the present invention it is possible to provide a multilayer piezoelectric element that does not contain lead as a component, has a small decrease in electrical insulation during use, and has a large amount of displacement when a voltage is applied.
  • FIG. 2 is a perspective view showing the state of internal electrode layers in the laminated piezoelectric element according to one aspect of the present invention
  • FIG. 4 is an explanatory diagram of the dimensions of each part necessary for calculating parameters R 1 , R 2 , R 3 and R 4 indicating the state of the internal electrode layers in the laminated piezoelectric element according to one aspect of the present invention
  • a multilayer piezoelectric element 100 according to one aspect of the present invention (hereinafter sometimes simply referred to as "this aspect") has piezoelectric ceramic layers, as schematically shown in cross-sectional views in FIGS. 10, internal electrode layers 20 arranged between the piezoelectric ceramic layers 10 and connection conductors 30 electrically connecting the internal electrode layers 20 every other layer.
  • the connection conductor 30 is formed on the surface of the laminated piezoelectric element 100.
  • the connection conductor 30 is formed inside the laminated piezoelectric element 100 so as to penetrate the piezoelectric ceramic layer 10. may have been
  • this side surface is provided with side margin portions 40 located between the Y-axis direction side surfaces and the internal electrode layers 20, and cover portions 50 located on the Z-axis direction upper and lower surfaces. good too.
  • an external electrode (not shown) that electrically connects the connection conductor 30 and the drive circuit may be formed on the surface of this side surface.
  • the piezoelectric ceramic layer 10 is mainly composed of alkali niobate having a perovskite structure.
  • the alkali niobate which is the main component, contains, as constituent elements, at least one alkali metal element selected from the group consisting of lithium (Li), sodium (Na) and potassium (K), and niobium (Nb). It is an oxide having a perovskite structure.
  • the perovskite structure has an A site located at the vertex of the unit cell, an O site located at the face center of the unit cell, and an octahedron having the O site as a vertex. It is a crystal structure having a B site.
  • alkali metal ions are located at the A site
  • niobium ions are located at the B site
  • oxide ions are located at the O site.
  • each site may contain various ions other than those described above.
  • the piezoelectric ceramic layer 10 is mainly composed of alkali niobate having a perovskite structure is performed by the following procedure.
  • a diffraction line was obtained by an X-ray diffraction (XRD) apparatus using Cu—K ⁇ rays. Measure your profile.
  • the method of exposing the piezoelectric ceramic layer 10 on the surface of the laminated piezoelectric element 100 is not particularly limited, and a method of cutting or polishing the piezoelectric element can be employed.
  • the means for pulverizing the laminated piezoelectric element 100 is not particularly limited, and a hand mill (mortar/pestle) or the like can be used.
  • a hand mill mortar/pestle
  • the piezoelectric ceramics It is determined that the layer 10 is mainly composed of a compound having a perovskite structure.
  • the XRD measurement is performed on the powder obtained by pulverizing the laminated piezoelectric element 100, the peak of the metal constituting the internal electrode layer 20 is also detected. comparison.
  • the piezoelectric ceramic layer 10 determined to be mainly composed of a compound having a perovskite structure or the powder prepared therefrom, high-frequency inductively coupled plasma (ICP) emission spectrometry, ion chromatography, or X-ray fluorescence (XRF)
  • ICP inductively coupled plasma
  • XRF X-ray fluorescence
  • An analyzer measures the ratio of each element contained. As a result of the measurement, both the total content of alkali metal elements and the content of niobium expressed in mol % (or atomic %) were greater than the contents of other elements, indicating that the perovskite structure, which is the main component, is determined to be an alkali niobate.
  • the piezoelectric ceramic layer 10 may contain other components as long as the main component is alkali niobate having a perovskite structure. These other components may be dissolved in any of the A site, B site, and O site of the perovskite structure described above, or may exist as a different phase between sintered particles of the main component.
  • the piezoelectric ceramic layer 10 may further contain at least one alkaline earth metal element selected from the group consisting of calcium (Ca), strontium (Sr) and barium (Ba), and silver (Ag). good.
  • the piezoelectric ceramic layer 10 becomes dense with a small sintered particle size, and exhibits excellent piezoelectricity.
  • the total content of alkaline earth metal elements is 100 mol % of the content of the elements in the B site of the alkali niobate, which is the main component (often in an ionic state). It is preferably more than 0.2 mol %, more preferably 0.3 mol % or more, even more preferably 0.5 mol % or more.
  • the content of silver is preferably more than 0.5 mol %, more preferably 0.7 mol % or more, relative to 100 mol % of the elements in the B site. 0 mol % or more is more preferable.
  • the total content of the alkaline earth metal elements is It is preferably 5.0 mol % or less, more preferably 3.0 mol % or less, even more preferably 1.0 mol % or less.
  • the silver content is preferably 5.0 mol % or less, more preferably 4.0 mol % or less, and further preferably 3.0 mol % or less. preferable.
  • the total content of the alkaline earth metal elements and the content of silver are set so that the total content of the alkaline earth metal elements is 0.2 per 100 mol % of the elements in the B site. It is more than 5.0 mol % and less than or equal to 5.0 mol %, preferably more than 0.5 mol % and less than or equal to 5.0 mol % of silver, and the total content of alkaline earth metal elements is 0.3 mol % or more.
  • silver is more preferably 0.7 mol % or more and 4.0 mol % or less, and the total content of alkaline earth metal elements is 0.5 mol % or more and 1.0 mol % or less. and more preferably 1.0 mol % or more and 3.0 mol % or less of silver.
  • the piezoelectric ceramic layer 10 may further contain manganese (Mn).
  • Mn manganese
  • the content of manganese should be 0.00% when the content of the element in the B site of the alkali niobate, which is the main component (actually, it is often in an ionic state), is 100 mol %. It is preferably 2 mol % or more, more preferably 0.3 mol % or more, and even more preferably 0.5 mol % or more.
  • the content of manganese is preferably 2.0 mol % or less with respect to 100 mol % of the elements in the B site. It is more preferably 5 mol % or less, and even more preferably 1.0 mol % or less.
  • the manganese content is preferably 0.2 mol % or more and 2.0 mol % or less, and 0.3 mol % or more, relative to 100 mol % of the elements in the B site. It is more preferably 1.5 mol % or less, and even more preferably 0.5 mol % or more and 1.0 mol % or less.
  • the piezoelectric ceramic layer 10 may further contain silicon (Si).
  • Si silicon
  • the piezoelectric ceramic layer 10 is densified, and excess Li that has not completely dissolved in the main component reacts with silicon to form compounds such as Li 2 SiO 3 and Li 4 SiO 4 . can suppress the formation of conductive compounds such as Li 3 NbO 4 .
  • the content of silicon should be 0.00% when the content of the element in the B site of the alkali niobate, which is the main component (actually, it is often in an ionic state), is 100 mol %. It is preferably 1 mol % or more, more preferably 0.5 mol % or more, and even more preferably 1.0 mol % or more.
  • the content of silicon is 3.0 mol % with respect to 100 mol % of the elements in the B site. or less, more preferably 2.5 mol % or less, and even more preferably 2.0 mol % or less.
  • the content of silicon is preferably 0.1 mol % or more and 3.0 mol % or less with respect to 100 mol % of the elements in the B site, and 0.5 mol % or more. 0.5 mol % or less is more preferable, and 1.0 mol % or more and 2.0 mol % or less is even more preferable.
  • the piezoelectric ceramic layer 10 may optionally contain at least one selected from first transition elements such as Sc, Ti, V, Cr, Fe, Co, Ni, Cu and Zn. good. By including these elements in appropriate amounts, it is possible to adjust the firing temperature of the laminated piezoelectric element 100, control grain growth, and extend the life in a high electric field.
  • first transition elements such as Sc, Ti, V, Cr, Fe, Co, Ni, Cu and Zn. good.
  • the piezoelectric ceramic layer 10 may contain at least one selected from Y, Mo, Ru, Rh and Pd, which are second transition elements, if necessary. By including these elements in appropriate amounts, it is possible to adjust the firing temperature of the laminated piezoelectric element 100, control grain growth, and extend the life in a high electric field.
  • the piezoelectric ceramic layer 10 may include third transition elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, and W, if necessary. , Re, Os, Ir, Pt and Au. By including these elements in appropriate amounts, it is possible to adjust the firing temperature of the laminated piezoelectric element 100, control grain growth, and extend the life in a high electric field.
  • third transition elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, and W, if necessary. , Re, Os, Ir, Pt and Au.
  • the piezoelectric ceramic layer 10 can contain a plurality of types of the above-described first transition element, second transition element, and third transition element.
  • the alkali niobate is represented by the following composition formula (1) from the viewpoint of exhibiting excellent piezoelectric properties and obtaining a long-life element when used under a high electric field. preferable.
  • M2 in the formula represents at least one alkaline earth metal element selected from the group consisting of calcium (Ca), strontium (Sr) and barium (Ba).
  • u, v, w, x, y, z and a are respectively 0.005 ⁇ u ⁇ 0.05, 0.002 ⁇ v ⁇ 0.05, 0.007 ⁇ u+v ⁇ 0.1, 0 ⁇ w ⁇ 1, 0.02 ⁇ x ⁇ 0.1, 0.02 ⁇ w+x ⁇ 1, 0 ⁇ y ⁇ 0.1, 0 ⁇ z ⁇ 0.4, 1 ⁇ a ⁇ 1.1 A numerical value that satisfies an inequality.
  • the alkali niobate is represented by the above compositional formula (1).
  • the piezoelectric ceramic layer 10 which has been confirmed to contain an alkali niobate having a perovskite structure as a main component, or a powder prepared therefrom, is subjected to high-frequency inductively coupled plasma (ICP) emission spectroscopy and ion chromatography.
  • ICP inductively coupled plasma
  • XRF X-ray fluorescence
  • the total number of moles of antimony, tantalum and niobium is calculated, and the ratio of the number of moles of each element to this is calculated.
  • the ratio of each element is within the range of the above composition formula (1), it is determined that the alkali niobate is represented by the above composition formula (1).
  • the internal electrode layer 20 has, as schematically shown in FIG.
  • the area percentage is 75% or more and 95% or less
  • the size of the gap 22 is 5% or less in average area percentage per location
  • lithium manganate is present in at least one location of the gap 22 23.
  • the internal electrode layer 20 has a conductive portion 21 made of metal with a silver content of 50% by mass or more. Since the content of silver in the conductive portion 21 is 50% by mass or more, the amount of expensive metals such as platinum and palladium used can be reduced, and the material cost of the laminated piezoelectric element 100 can be suppressed. In addition, since the ratio of silver, which is excellent in conductivity, increases, the electrical resistivity decreases, and the electrical loss when driving the multilayer piezoelectric element 100 is reduced.
  • a silver-palladium alloy is exemplified as a metal having a silver content of 50% by mass or more.
  • the content of silver in the conductive portion 21 is preferably 70% by mass or more, more preferably 80% by mass or more.
  • the content of silver in the internal electrode layer 20 can be confirmed by performing elemental analysis of the internal electrode layer 20 using various measuring instruments and calculating the mass ratio of silver to all the detected elements.
  • the measuring instrument used is a scanning electron microscope (SEM) or an energy dispersive X-ray spectrometer (EDS) attached to a transmission electron microscope (TEM). Or wavelength dispersive X-ray spectrometer (Wavelength Dispersive X-ray Spectrometer, WDS), electron probe microanalyzer (Electron Probe Micro Analyzer, EPMA) and laser irradiation type inductively coupled plasma mass spectrometer (LA-ICP-MS), etc. exemplified.
  • the area percentage of the conductive portions 21 in the internal electrode layers 20 is set to 75% or more and 95% or less.
  • R 1 By setting the area percentage (hereinafter sometimes simply referred to as “R 1 ”) to 75% or more, a sufficient voltage is applied to the piezoelectric ceramic layer 10 when driving the multilayer piezoelectric element 100, A large displacement can be obtained.
  • R1 is preferably 80% or more.
  • R1 by setting R1 to 95% or less, the restraining force by the internal electrode layers 20 generated when the piezoelectric ceramic layers 10 are displaced is reduced, and a large displacement can be obtained. From this point of view, R 1 is preferably 93% or less. For the reason described above, R1 is preferably 80% or more and 93% or less.
  • the internal electrode layer 20 has a gap portion 22 where the conductive portion 21 does not exist.
  • the gaps 22 are sized such that the average area percentage (hereinafter sometimes simply referred to as “R 2 ”) per portion of the entire internal electrode layer 20 is 5% or less.
  • R2 is preferably 3% or less.
  • the lower limit of R2 is not limited, it is often 0.01% or more in the laminated piezoelectric element 100 having R1 of 75% or more and 95% or less, which is obtained by a general manufacturing method.
  • the ratio of the total area of the gaps 22 to the area of the internal electrode layers 20 is 5% or more and 25% or less in terms of area percentage, that is, the value obtained by subtracting the aforementioned R1 from 100%. Therefore, the area percentage of the total area of the gaps 22 corresponding to the above-mentioned preferable value of R1 is 7% or more and 20% or less.
  • the gap 22 contains lithium manganate 23 in at least one location.
  • Lithium manganate 23 is a compound having a lower electrical resistivity than alkaline niobate, which is the main component of piezoelectric ceramic layer 10 .
  • the presence of such a compound in the piezoelectric ceramic layer 10 causes a decrease in electrical resistivity of the piezoelectric ceramic layer 10 and the multilayer piezoelectric element 100 as a whole during use.
  • the lithium manganate 23 is present in the interstices 22 of the internal electrode layers 20, although the electrical resistivity of the interstices 22 is lower than in the case where the alkali niobate is present, the interstices 22 are included. Since the internal electrode layer 20 is originally conductive, the adverse effect on the electrical resistivity of the laminated piezoelectric element 100 is limited. Therefore, the presence of the lithium manganate 23 in the interstices 22 of the internal electrode layers 20 reduces the amount of lithium manganate in the piezoelectric ceramic layer 10, and the entire piezoelectric ceramic layer 10 and the laminated piezoelectric element 100 in use. decrease in electrical resistivity is suppressed.
  • the lithium manganate 23 contained in the gap 22 includes those represented by various composition formulas such as Li 2 MnO 3 , LiMn 2 O 4 and LiMnO 2 . Express.
  • the area ratio of the lithium manganate 23 contained in the gaps 22 to the total area of the internal electrode layers 20 (hereinafter sometimes simply referred to as “R 3 ”) is preferably 1% or more. , more preferably 2% or more. As a result, deterioration of the electrical insulation of the laminated piezoelectric element 100 during use is significantly reduced.
  • R3 is not limited, as described above, the upper limit of the ratio of the total area of the gaps 22 to the area of the internal electrode layers 20 is 25%, and the preferable upper limit is 20%. necessarily lower than these values. For the reasons described above, R3 is preferably 1% or more and 25% or less, more preferably 2% or more and 20% or less.
  • the ratio of the area of the lithium manganate 23 contained in the gap 22 to the total area of the gap 22 (hereinafter sometimes simply referred to as “R 4 ”) is preferably 10% or more, It is more preferably 20% or more. As a result, deterioration of the electrical insulation of the laminated piezoelectric element 100 during use is significantly reduced.
  • the upper limit of R 4 is not limited, and may be 100%, that is, a state in which all the gaps 22 are filled with lithium manganate 23 .
  • the laminated piezoelectric element 100 is cut along a plane perpendicular to the plane perpendicular to the lamination direction, passing near the center of gravity, and the cut surface is polished to expose the internal electrode layers 20 .
  • the cutting is performed while avoiding the connecting conductor 30.
  • the exposed internal electrode layers 20 are observed with an optical microscope to identify the conductive portions 21 having metallic luster and the gaps 22 where the conductive portions are interrupted. Identify the location of the speckled portion that is recognized by the difference in lightness or saturation.
  • the spotted portion often has an orange or black color due to the coloring of manganese.
  • Li, Mn and Nb were analyzed using a laser irradiation type inductively coupled plasma mass spectrometer (LA-ICP-MS) for each of the speckled portions and portions where similar specks did not exist in the piezoelectric ceramic layer 10. Measure the content.
  • LA-ICP-MS laser irradiation type inductively coupled plasma mass spectrometer
  • R 1 , R 2 , R 3 and R 4 described above are measured and calculated in the following procedure.
  • an optical microscope image of a cross section of the laminated piezoelectric element 100 determined to contain lithium manganate 23 in the interstices 22 of the internal electrode layers 20 by the above-described procedure is taken from the internal electrode layers 20 exposed there. , arbitrarily select three consecutive sheets (layers).
  • Next for the selected internal electrode layers 20, as schematically shown in FIG . Length occupied by each lithium manganate 23 (L M11 , L M12 , . ) , the length occupied by each lithium manganate 23 (L M21 , L M22 , .
  • each lithium manganate 23 (L M31 , L M32 , . . . , L M3r ) and the length occupied by each lithium manganate 23 (L M31 , L M32 , . . . , L M3r ) are measured.
  • the suffixes a, b, and c respectively denote the number of gaps 22 present in each layer, and the suffixes p, q, and r denote the number of lithium manganate 23 present in each layer.
  • R 1 is determined by the following formula (2)
  • R 2 is determined by the following formula (3)
  • R 3 is determined by the following formula (4)
  • R 4 is determined by the following formula (5). calculate.
  • connection conductor 30 electrically connects every other internal electrode layer 20 .
  • the material of the connection conductor 30 has high conductivity and is physically and chemically stable under the polarization conditions and the usage environment of the element, which will be described later. is not particularly limited. Examples include silver (Ag), copper (Cu), gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), and alloys thereof.
  • the connecting conductor 30 is formed inside the laminated piezoelectric element 100 so as to penetrate the piezoelectric ceramic layer 10, the silver content is 50%, similarly to the conductive portion 21 of the internal electrode layer 20 described above. It is preferable to use the metal in mass % or more.
  • the side margin portion 40 and the cover portion 50 function as protection portions that protect the piezoelectric ceramic layers 10 and the internal electrode layers 20 .
  • the side margin portion 40 and the cover portion 50 are made of alkali niobate, similar to the piezoelectric ceramic layer 10, from the viewpoint of the shrinkage rate during firing of the laminated piezoelectric element 100 and the relaxation of internal stress in the laminated piezoelectric element 100. It is preferably formed of a sintered body containing salt as a main component. However, the material for forming the side margin portions 40 and the cover portion 50 need not contain alkali niobate as a main component as long as the material has high insulating properties.
  • the external electrode has a function of electrically connecting the connection conductor 30 and the drive circuit. Moreover, when this is formed on the piezoelectric ceramics layer 10, it also has a function of applying a voltage thereto.
  • the material of the external electrode is not particularly limited as long as it has high conductivity and is physically and chemically stable under the polarization conditions and the usage environment of the piezoelectric element. Examples include silver (Ag), copper (Cu), gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), and alloys thereof.
  • the laminated piezoelectric element according to this aspect is obtained by, for example, mixing raw material powders in a predetermined ratio to obtain a raw material mixed powder, calcining the raw material mixed powder, and Obtaining a calcined powder as a component, mixing the calcined powder with a binder and a dispersion medium to prepare a slurry, forming the slurry into a sheet to obtain a green sheet, silver on the green sheet A paste containing a metal and a manganese compound whose After removing the binder from the green compact, firing it to obtain a laminated piezoelectric ceramic, applying a conductor paste to the surface of the laminated piezoelectric ceramic where the internal electrode layer is exposed, and baking it to connect conductor and applying a high voltage between the connection conductors to polarize the piezoelectric ceramic layer.
  • a calcined powder as a component
  • mixing the calcined powder with a binder and a dispersion medium to prepare a slurry
  • raw material powders are mixed at a predetermined ratio to obtain a raw material mixed powder.
  • raw material powders to be used include lithium carbonate (Li 2 CO 3 ) as a lithium compound, sodium carbonate (Na 2 CO 3 ) and sodium hydrogen carbonate (NaHCO 3 ) as sodium compounds, and potassium carbonate ( K 2 CO 3 ) and potassium hydrogen carbonate (KHCO 3 ), and niobium pentoxide (Nb 2 O 5 ) as a niobium compound.
  • frequently used compounds include tantalum pentoxide (Ta 2 O 5 ) as a tantalum compound and antimony trioxide (Sb 2 O 3 ) as an antimony compound.
  • the method of mixing the raw material powders is not particularly limited as long as each powder is uniformly mixed while suppressing the contamination of impurities, and either dry mixing or wet mixing may be employed.
  • dry mixing using a ball mill for example, partially stabilized zirconia (PSZ) balls are used, and after stirring for about 8 to 60 hours with a ball mill using an organic solvent such as ethanol as a dispersion medium, The organic solvent may be evaporated and dried.
  • PSZ partially stabilized zirconia
  • the mixed raw material powder is calcined to obtain a calcined powder.
  • the calcination is carried out under conditions under which raw material powders react with each other to obtain an alkali niobate having a predetermined composition.
  • One example is firing in air at a temperature of 700 to 1000° C. for 1 to 10 hours.
  • the calcined powder may be directly used to prepare a slurry, but it is preferable to pulverize the powder with a ball mill, a stamp mill, or the like prior to this, in order to obtain a smooth green sheet through a uniform slurry.
  • the subsequent operations may be performed on this powder without preparing the raw material mixed powder and preparing the calcined powder described above.
  • the calcined powder is mixed with a binder and a dispersion medium to prepare a slurry.
  • a binder a binder that can hold the shape of the green sheet to be described later and is volatilized without leaving carbon or the like by firing or a binder removal treatment prior thereto is used.
  • binders examples include polyvinyl alcohol-based, polyvinyl butyral-based, cellulose-based, urethane-based and vinyl acetate-based binders.
  • the amount of the binder used is also not particularly limited, but since it is removed in the post-process, it is preferable to reduce the amount as much as possible within the range where the desired moldability and shape retention can be obtained, in terms of reducing raw material costs. .
  • dispersion medium one that does not cause aggregation of the calcined powder and the binder and can be easily removed by volatilization or the like after forming the green sheet described later is used.
  • examples of usable dispersion media include water and alcoholic solvents.
  • Components that adjust the properties of the slurry such as dispersants, plasticizers and thickeners, may be added to the slurry.
  • various components to be contained in the piezoelectric ceramic layer may be added to the slurry.
  • alkaline earths such as calcium carbonate ( CaCO3 ), calcium metasilicate ( CaSiO3 ) and calcium orthosilicate ( Ca2SiO4 ), strontium carbonate ( SrCO3 ) and barium carbonate ( BaCO3 ).
  • silver-containing compounds such as silver oxide (AgO)
  • lithium-containing compounds such as lithium carbonate, lithium fluoride and lithium manganate
  • manganese-containing compounds such as manganese oxide, manganese carbonate, manganese acetate and lithium manganate
  • silicon-containing compounds such as silicon dioxide ( SiO2 ), calcium metasilicate ( CaSiO3 ) and calcium orthosilicate ( Ca2SiO4 ).
  • the method of mixing the calcined powder, binder, and dispersion medium is not particularly limited as long as each component is uniformly mixed while preventing impurities from being mixed.
  • One example is ball mill mixing.
  • the obtained slurry is molded to obtain a green sheet.
  • a commonly used method such as a doctor blade method can be adopted.
  • an internal electrode paste containing a metal with a silver content of 50% by mass or more and a manganese compound is printed on the obtained green sheets. Since the internal electrode paste contains a manganese compound, the lithium that did not fully dissolve into the perovskite structure during firing, which will be described later, reacts with the manganese compound in the internal electrode layer to generate lithium manganate, thereby creating a gap. part is formed.
  • the amount of the manganese compound added to the internal electrode paste should be 0.1% by mass or more and 3% by mass or less. preferably.
  • R1 and R2 are also affected by the composition of the piezoelectric ceramic layer, the amount of vehicle in the internal electrode paste, the printed film thickness, and the like. For this reason, the amount of the manganese compound added to the paste is controlled under the manufacturing conditions that are actually employed.
  • the value of 2 may be determined to be a predetermined value.
  • glass frit or powder having the same composition as the alkali niobate powder contained in the green sheet may be added in order to improve the adhesion strength to the piezoelectric ceramic layer after firing.
  • the internal electrode paste on the green sheet it may be printed with a space that will be the side margin when the laminated piezoelectric element is formed.
  • a predetermined number of green sheets printed with the internal electrode paste are laminated, and the green sheets are pressure-bonded to each other to produce a green body.
  • Lamination and pressure bonding may be carried out by a commonly used method, such as a method in which laminated green sheets are heated and pressed in the direction of lamination, and thermocompression bonding is performed by the action of a binder.
  • green sheets may be added to both ends in the lamination direction to serve as cover portions when the laminated piezoelectric element is formed.
  • the green sheet to be added may have the same composition as the green sheet on which the internal electrode paste is printed, or may have a different composition. From the viewpoint of uniforming the shrinkage rate during firing, the composition of the green sheets to be added is preferably the same as or similar to the composition of the green sheets printed with the internal electrode paste.
  • the binder may be removed from the green body prior to firing. In this case, removal of the binder and firing may be performed continuously using the same firing apparatus.
  • the conditions for removing and firing the binder may be appropriately set in consideration of the volatilization temperature and content of the binder, the sinterability of the alkali niobate, the heat resistance of the metal contained in the internal electrode paste, and the like.
  • An example of the conditions for removing the binder is an atmospheric atmosphere at a temperature of 300 to 500° C. for 5 to 20 hours. Examples of firing conditions include 800° C. to 1100° C. for 1 hour to 5 hours in an air atmosphere.
  • lithium that did not fully dissolve in the perovskite structure reacts with the manganese compound in the internal electrode layer to form lithium manganate, thereby forming gaps. be done.
  • silver in the internal electrode layers diffuses into the piezoelectric ceramic layers during firing, which may form gaps.
  • the green sheet forming the green body contains at least one alkaline earth metal element selected from the group consisting of calcium, strontium and barium, silver and alkaline earth elements diffused from the internal electrode layers during firing. Due to the interaction with the metal element, the obtained piezoelectric ceramic layer becomes dense with fine sintered particles.
  • the green sheet forming the green body when the green sheet forming the green body contains silicon, it can act as a sintering aid to lower the firing temperature.
  • silicon reacts with elements contained in the alkali niobate or separately added elements during firing to form Li 2 SiO 3 , Li 4 SiO 4 , K 3 Nb 3 O 6 Si 2 O 7 , KNbSi 2 .
  • a crystalline phase such as O 7 , K 3 LiSiO 4 or KLi 3 SiO 4 or an amorphous phase containing these elements, the volatilization of alkali metals and precipitation between sintered particles can be suppressed. .
  • connection conductor Next, a conductive paste is applied to the surfaces of the obtained laminated piezoelectric ceramics where the internal electrode layers are exposed, and then baked to form connection conductors.
  • Example 1 A calcined powder represented by the composition formula Li 0.06 Na 0.52 K 0.42 NbO 3 was prepared as an alkali niobate powder having a perovskite structure. With respect to 100 mol% of this calcined powder, 0.65 mol% Li2CO3 , 1.3 mol% SiO2 , 0.5 mol% CaCO3 and 0.5 mol% MnCO3 , and polyvinyl A butyral-based binder was added, respectively, and wet-ball-mill mixed. The resulting mixed slurry was molded with a doctor blade to obtain a green sheet with a thickness of 30 ⁇ m.
  • MnO manganese oxide
  • Example 2 In the same manner as in Example 1, except that the amount of manganese oxide (MnO) added to the Ag—Pd alloy paste was set to 0.5% by mass (Example 2) and 3% by mass (Example 3). Laminated piezoelectric elements according to Examples 2 and 3 were obtained.
  • MnO manganese oxide
  • Comparative example 1 A multilayer piezoelectric element according to Comparative Example 1 was obtained in the same manner as in Example 1, except that manganese oxide (MnO) was not added to the Ag—Pd alloy paste.
  • MnO manganese oxide
  • Comparative example 2 A laminated piezoelectric element according to Comparative Example 2 was obtained in the same manner as in Example 1, except that the amount of manganese oxide (MnO) added to the Ag—Pd alloy paste was 10% by mass.
  • MnO manganese oxide
  • the displacement performance d * 33 per unit voltage in one piezoelectric ceramic layer was calculated.
  • the obtained displacement performance d * 33 is shown in Table 1 as a ratio when the displacement performance d * 33 of the multilayer piezoelectric element according to Comparative Example 1 is set to 100.
  • the laminated piezoelectric element having the alkaline niobate-based piezoelectric ceramic layers includes gaps of a predetermined ratio and size in the internal electrode layers, and lithium manganate is contained in the gaps. It can be said that by using the material as a material, the deterioration of the electrical insulation during use is reduced and the displacement performance is also improved.
  • a laminated piezoelectric element using an alkali niobate-based piezoelectric ceramic less degraded in electrical insulation during use and to have a large displacement when a voltage is applied. can.
  • Such a laminated piezoelectric element is suitable for a haptic module that requires a large amount of displacement and a long life.
  • the laminated piezoelectric element does not contain lead as a component, it is useful in that it can reduce the load on the environment during its life cycle.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

Un élément piézoélectrique multicouche selon un aspect de la présente invention comprend des couches céramiques piézoélectriques qui sont principalement composées d'un sel de niobate alcalin ayant une structure pérovskite, et une couche d'électrode interne 20 qui est disposée entre les couches céramiques piézoélectriques et qui a une partie conductrice qui a une teneur en argent de 50 % en masse ou plus, dans lequel : le pourcentage de surface (R1) occupée par la partie conductrice 21 est de 75 % à 95 % ; la couche d'électrode interne a également des parties interstitielles 22 dans lesquelles la partie conductrice 21 n'est pas présente, et qui ont un pourcentage de surface moyen (R2) pour une partie interstitielle de 5 % ou moins ; et au moins l'une des parties interstitielles 22 contient du manganate de lithium 23.
PCT/JP2022/034339 2021-10-12 2022-09-14 Élément piézoélectrique multicouche WO2023063007A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113451496A (zh) * 2020-03-27 2021-09-28 太阳诱电株式会社 压电元件及其制造方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004047958A (ja) * 2002-05-20 2004-02-12 Matsushita Electric Ind Co Ltd 積層圧電トランスの製造方法
WO2006068245A1 (fr) * 2004-12-24 2006-06-29 Murata Manufacturing Co., Ltd Composant ceramique piezoelectrique multicouche et procede pour sa fabrication
JP2014026998A (ja) * 2012-07-24 2014-02-06 Taiyo Yuden Co Ltd 圧電素子及びその製造方法
JP2021158250A (ja) * 2020-03-27 2021-10-07 太陽誘電株式会社 圧電素子及びその製造方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004047958A (ja) * 2002-05-20 2004-02-12 Matsushita Electric Ind Co Ltd 積層圧電トランスの製造方法
WO2006068245A1 (fr) * 2004-12-24 2006-06-29 Murata Manufacturing Co., Ltd Composant ceramique piezoelectrique multicouche et procede pour sa fabrication
JP2014026998A (ja) * 2012-07-24 2014-02-06 Taiyo Yuden Co Ltd 圧電素子及びその製造方法
JP2021158250A (ja) * 2020-03-27 2021-10-07 太陽誘電株式会社 圧電素子及びその製造方法

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113451496A (zh) * 2020-03-27 2021-09-28 太阳诱电株式会社 压电元件及其制造方法
CN113451496B (zh) * 2020-03-27 2024-05-14 太阳诱电株式会社 压电元件及其制造方法
US12010921B2 (en) 2020-03-27 2024-06-11 Taiyo Yuden Co., Ltd. Piezoelectric element with lithium manganate-containing ceramic layers and silver-containing internal electrodes

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