WO2023063356A1 - Piezoelectric layered element - Google Patents

Piezoelectric layered element Download PDF

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WO2023063356A1
WO2023063356A1 PCT/JP2022/038058 JP2022038058W WO2023063356A1 WO 2023063356 A1 WO2023063356 A1 WO 2023063356A1 JP 2022038058 W JP2022038058 W JP 2022038058W WO 2023063356 A1 WO2023063356 A1 WO 2023063356A1
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piezoelectric
internal electrode
weight
parts
electrode layers
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Japanese (ja)
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正紀 加藤
慎一郎 川田
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株式会社村田製作所
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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
    • C04B35/46—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 titanium oxides or titanates
    • C04B35/462—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 titanium oxides or titanates based on titanates
    • C04B35/465—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 titanium oxides or titanates based on titanates based on alkaline earth metal titanates
    • C04B35/468—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 titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates
    • 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 a piezoelectric laminated element.
  • Barium titanate is known as a piezoelectric material that is a perovskite-type metal oxide.
  • material development based on the composition of barium titanate is being carried out.
  • a piezoelectric element or the like to which Cu is added is disclosed. Although these piezoelectric elements and the like are superior in mechanical quality factor to barium titanate, they have low piezoelectric characteristics, and therefore require a high voltage to drive the elements.
  • Patent Document 1 For the purpose of improving the piezoelectric properties, in Patent Document 1, an oxide containing Ba, Ca, Ti, and Zr, and Mn are contained, and the Ca molar ratio x is 0 with respect to the sum of the Ba and Ca containing molar numbers.
  • Zr molar ratio y is 0.02 ⁇ y ⁇ 0.095 and y ⁇ x with respect to the sum of the number of moles containing Ti and Zr, and Ba and Ca with respect to the sum of Ti and Zr moles
  • the molar sum ratio a is 1.00 ⁇ a ⁇ 1.01
  • Mn is 0.02 parts by weight or more and 0.40 parts by weight in terms of metal with respect to 100 parts by weight of the oxide containing Ba, Ca, Ti, and Zr
  • a piezoelectric material is disclosed that includes:
  • Patent Document 1 many evaluations of piezoelectric materials in an air atmosphere are described. : 5 mol % to 15 mol % is suitable, and particularly for actuator applications, Ca: 14 mol % to 17.5 mol % and Zr: 5.5 mol % to 9 mol % are disclosed.
  • the driving voltage of the element can be lowered by forming a laminated structure having internal electrode layers.
  • a reducing atmosphere is required to prevent oxidation of the electrode metal layer during the co-sintering process of the laminated structure.
  • the thin layered structure may not produce the desired results. Piezoelectric characteristics cannot be obtained.
  • the present invention has been made to solve the above-mentioned problems, and a piezoelectric multilayer element capable of obtaining optimum piezoelectric characteristics even in the case of a thin-layer multilayer structure using internal electrode layers containing Ni as a main component. intended to provide
  • a piezoelectric multilayer element of the present invention includes a plurality of piezoelectric ceramic layers, internal electrode layers provided between the piezoelectric ceramic layers, and external electrodes electrically connected to the internal electrode layers, and comprises the piezoelectric body
  • the ceramic layer is composed of an oxide containing Ba, Ca, Ti and Zr and a piezoelectric material containing Mn, and the molar ratio x of Ca to the sum of Ba and Ca is 0.005 ⁇ x ⁇ 0.005. 0175, the molar ratio y of the Zr to the sum of the Ti and the Zr is 0.005 ⁇ y ⁇ 0.0175, and the content of the Mn with respect to 100 parts by weight of the oxide is 0.01 in terms of MnO. It is characterized in that it is 15 parts by weight or more and 5.0 parts by weight or less, and the internal electrode layer contains Ni as a main component.
  • the present invention it is possible to provide a piezoelectric laminated element capable of obtaining optimum piezoelectric characteristics even in the case of forming a thin-layer laminated structure using internal electrode layers containing Ni as a main component.
  • FIG. 1A is a cross-sectional view schematically showing an example of the configuration of the piezoelectric laminated element of the present invention.
  • FIG. 1B is a plan view of the piezoelectric laminate of FIG. 1A.
  • the piezoelectric laminated element of the present invention will be described below.
  • the present invention is not limited to the following configurations, and can be appropriately modified and applied without changing the gist of the present invention. Combinations of two or more of the individual desirable configurations described below are also part of the present invention.
  • the piezoelectric laminated element of the present invention includes a plurality of piezoelectric ceramic layers.
  • the piezoelectric ceramic layer is composed of an oxide containing Ba, Ca, Ti and Zr, and a piezoelectric material containing Mn.
  • the oxide has the following general formula (1): (Ba 1-x Ca x ) a (Ti 1-y Zr y ) b O 3 (1) wherein x satisfies 0.005 ⁇ x ⁇ 0.0175 and y satisfies 0.005 ⁇ y ⁇ 0.0175 in the general formula (1).
  • a perovskite-type metal oxide refers to a metal oxide having a perovskite-type structure, which is ideally a cubic system.
  • Metal oxides with a perovskite structure are generally represented by the chemical formula ABO3 .
  • the elements A and B occupy specific positions in the unit lattice called A sites and B sites in the form of ions, respectively.
  • a sites and B sites in the form of ions, respectively.
  • the A element is located at the vertices of the cube, and the B element is located at the center of the body.
  • the O element occupies the face-center position of the cube as an anion of oxygen.
  • the perovskite-type metal oxide represented by the above general formula (1) means that the elements located at the A site are Ba and Ca, and the elements located at the B site are Ti and Zr. However, part of Ba and Ca may be located at the B site, and part of Ti and Zr may be located at the A site.
  • the molar ratio x of Ca to the sum of Ba and Ca in the oxide is 0.005 ⁇ x ⁇ 0.0175
  • the molar ratio y of Zr to the sum of Ti and Zr is 0.005 ⁇ y ⁇ 0.0175.
  • the piezoelectric efficiency is the value obtained by dividing the piezoelectric constant d31 by the relative dielectric constant ⁇ r .
  • the molar ratio (a/b) of the element at the A site and the element at the B site is usually 1.000.
  • the molar ratio (a/b) of the sum of Ba and Ca to the sum of Ti and Zr may be 1.000 or more and 1.010 or less.
  • the molar ratio (a/b) is 1.003 or more and 1.007 or less.
  • the means for measuring the composition of the oxide is not particularly limited, and examples thereof include X-ray fluorescence spectroscopy (XRF), inductively coupled plasma (ICP) emission spectroscopy, and atomic absorption spectroscopy. By either means, the weight ratio and composition ratio of each element contained in the oxide can be calculated.
  • the content of Mn with respect to 100 parts by weight of the oxide is 0.15 parts by weight or more and 5.0 parts by weight or less in terms of MnO.
  • the content of Mn is determined from the content of each metal such as Ba, Ca, Ti, Zr and Mn obtained by measuring the piezoelectric material by XRF, for example, and Ba, Ca, Ti and It represents a value obtained from the ratio of the weight of MnO to the total weight of 100 parts by weight of Zr converted to oxide.
  • the Mn content is less than 0.15 parts by weight in terms of MnO, the effect of the polarization treatment necessary for driving the piezoelectric laminated element will not be sufficient.
  • the Mn content exceeds 5.0 parts by weight in terms of MnO, the content of the metal oxide represented by the general formula (1) in the piezoelectric material decreases, resulting in insufficient piezoelectric efficiency.
  • the piezoelectric material may further contain sintering aids and additives as subcomponents.
  • sintering aids include Si.
  • the content of Si is not particularly limited, but in order to allow the piezoelectric material to be fired at a low temperature and to prevent the material from diffusing from the internal electrode layer, the content of Si is calculated as SiO 2 with respect to 100 parts by weight of the oxide, 0.2 parts by weight or more and 1.0 parts by weight or less is preferable.
  • Additives include, for example, Mg.
  • the content of Mg is not particularly limited, but in order to ensure reliability as a product of the piezoelectric laminated element of the present invention, it should be 0.1 parts by weight or more and 0.5 parts by weight in terms of MgO with respect to 100 parts by weight of the oxide. Part by weight or less is preferred.
  • the piezoelectric material may contain metals such as Sr, Nb, and Hf in amounts that are included as inevitable components in commercially available raw materials.
  • the piezoelectric laminated element of the present invention includes internal electrode layers containing Ni as a main component.
  • the fact that the internal electrode layers contain Ni as a main component means that the internal electrode layers contain the largest amount of Ni among the materials constituting the internal electrode layers, and that the internal electrode layers contain Ni in an amount of 50% by weight or more.
  • the Ni content of the internal electrode layers may be 100% by weight.
  • Materials other than Ni that can be used for the internal electrode layers include piezoelectric laminated elements such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, and Cu. metals and their compounds commonly used in
  • the internal electrode layer may be formed by laminating two or more kinds of materials.
  • all the internal electrode layers may be made of the same material, or may be made of different materials.
  • a piezoelectric laminated element of the present invention includes a plurality of piezoelectric ceramic layers, internal electrode layers provided between the piezoelectric ceramic layers, and external electrodes electrically connected to the internal electrode layers.
  • the piezoelectric laminated element of the present invention is manufactured by firing under a reducing atmosphere in order to co-sinter the internal electrode layers containing Ni as a main component, since the piezoelectric ceramic layers are made of the above piezoelectric material. It has a high piezoelectric constant d31 and a high piezoelectric efficiency even when
  • each piezoelectric ceramic layer is not particularly limited, the structure of the piezoelectric laminated element of the present invention is suitable when the average thickness of each piezoelectric ceramic layer is 30 ⁇ m or less. is.
  • the average thickness of each piezoelectric ceramic layer is preferably 10 ⁇ m or more.
  • the thickness of the piezoelectric ceramic layer means the thickness of the piezoelectric ceramic layer between the internal electrode layers.
  • the thickness of the piezoelectric ceramic layer is determined as follows.
  • a section (WT section) in the width (W) direction and lamination (T) direction passing through the center of the piezoelectric laminated element in the length (L) direction is exposed by polishing. If necessary, the polished surface is etched to remove the internal electrode layer stretched by polishing. Then, the exposed cross section is observed with a scanning electron microscope.
  • a straight line Lc extending in the lamination direction T of the piezoelectric ceramic layers and the internal electrode layers and passing through the center of the laminate is drawn.
  • a plurality of straight lines parallel to the straight line Lc are drawn at regular intervals.
  • the interval between adjacent straight lines may be determined to be about 5 to 10 times the thickness of the piezoelectric ceramic layer to be measured.
  • the same number of straight lines are drawn on both sides of the straight line Lc. That is, an odd number of straight lines are drawn by combining the straight lines Lc. For example, five straight lines are drawn by combining the straight lines Lc.
  • the thickness of the piezoelectric ceramic layer is measured on each straight line such as the straight line Lc.
  • the straight line Lc Measure the thickness or distance on a straight line away from Let the average value of these values be the thickness of the piezoelectric ceramic layer.
  • the number of piezoelectric ceramic layers may be 2 or more, for example, 10 or more.
  • the piezoelectric laminated element of the present invention has a small change in relative dielectric constant due to temperature, and has high piezoelectric characteristics in the temperature range of 10° C. to 80° C. even if it is a thin layer laminated structure in which the piezoelectric ceramic layer has a thickness of 30 ⁇ m or less. can be obtained, it is suitable as a piezoelectric laminated element having power saving properties suitable for use in general portable equipment and the like.
  • FIG. 1A is a cross-sectional view schematically showing an example of the configuration of the piezoelectric laminated element of the present invention.
  • FIG. 1B is a plan view of the piezoelectric laminate of FIG. 1A.
  • a piezoelectric laminated element 10 shown in FIGS. 1A and 1B includes a piezoelectric ceramic body 1 and external electrodes 4 a and 4 b provided on the surface of the piezoelectric ceramic body 1 .
  • the external electrodes 4a and 4b are provided at both ends of the piezoelectric ceramic body 1, and the external electrodes 4b extend to the front and back of the piezoelectric ceramic body 1 in order to increase the driving layers.
  • the external electrodes 4a and 4b are made of, for example, the same material as the internal electrode layers described above.
  • piezoelectric ceramic layers 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i and 2j and internal electrode layers 3a, 3b, 3c, 3d and 3e are arranged.
  • 3f, 3g, 3h and 3i are alternately stacked.
  • the piezoelectric ceramic layers 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i and 2j are made of the piezoelectric material described above.
  • the internal electrode layers 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h and 3i are made of a conductive material containing Ni as a main component.
  • one end of the internal electrode layers 3a, 3c, 3e, 3g, and 3i is electrically connected to one external electrode 4a, and one end of the internal electrode layers 3b, 3d, 3f, and 3h is electrically connected to the other external electrode. It is electrically connected to the electrode 4b.
  • the piezoelectric laminated element of the present invention is manufactured, for example, by the following method.
  • raw material powder prepared by a solid phase method in which oxides, carbonates, etc. are reacted at high temperature, and wet synthesis such as an alkoxide method or a hydrothermal synthesis method.
  • a raw material powder prepared according to the method is prepared.
  • the sintering aids and additives in addition to powders of oxides and carbonates, solutions of alkoxides and organic metals can also be used.
  • an organic binder, a plasticizer, and a solvent are added to form a slurry, which is formed into a sheet to obtain a green sheet.
  • an internal electrode layer containing Ni as a main component is formed on one surface of some of the green sheets.
  • the method for forming the internal electrode layers may be formation by screen printing or the like, vapor deposition, or plating.
  • this laminate is fired at a predetermined temperature (for example, 1200° C. or higher and 1300° C. or lower) in a reducing atmosphere to obtain a ceramic laminate.
  • a predetermined temperature for example, 1200° C. or higher and 1300° C. or lower
  • external electrodes are formed on both end surfaces of the ceramic laminate so as to be electrically connected to the internal electrode layers.
  • External electrodes may be provided on the front and back surfaces of the ceramic laminate.
  • the external electrodes are formed by applying a metal powder paste as a material to a ceramic laminate obtained by firing the laminate and then baking the laminate. can be applied and formed simultaneously with the ceramic laminate.
  • the external electrodes can be formed by sputtering.
  • the piezoelectric laminated element of the present invention is obtained.
  • the composition of the piezoelectric material in the piezoelectric laminated element is the same as the composition of the mixture of the mixed raw material powder, MnCO 3 , MgCO 3 and SiO 2 .
  • BaTiO 3 , CaTiO 3 and BaZrO 3 were prepared as calcined oxide raw material powders.
  • a mixed raw material powder was prepared so that the piezoelectric material had a composition ratio shown in Table 1.
  • the a/b ratio in Table 1 is the molar ratio (a/b) of the sum of Ba and Ca to the sum of Ti and Zr.
  • sample number No. 1 to No. No. 11 is the composition of the present invention.
  • 12 to No. No. 17 is the composition of the comparative example.
  • the sample No. shown in Table 1 was tested. 1 to No. 0.00 parts by weight or more and 15.00 parts by weight or less of MnCO3 , 0.24 parts by weight of MgCO3 , 0.8 parts by weight of SiO2 , and After adding 10 parts by weight of polyvinyl butyral (PVB) resin, 150 parts by weight of toluene and 150 parts by weight of ethanol, the mixture was pulverized and mixed with a ball mill to prepare a ceramic slurry. This ceramic slurry was applied with a doctor blade and then dried to obtain a green sheet with a thickness of 10 ⁇ m. Further, on some of the green sheets, surface electrodes of a predetermined shape are formed by Ni metal paste printing.
  • PVB polyvinyl butyral
  • a structure was obtained in which a total of 10 ceramic layers were laminated and press-bonded. After cutting this structure into a size of 5 mm ⁇ 20 mm, it was degreased and fired at 1250° C. in a reducing atmosphere. Furthermore, external electrodes are formed on both end surfaces of the piezoelectric ceramic body after the firing treatment, and a piezoelectric laminated element structure in which the internal electrode layers are alternately connected to one of the external electrodes is formed.
  • the polarization treatment was performed by applying a voltage corresponding to . An alternating current of 1 kV/mm was applied to this polarized piezoelectric laminated element to drive it, and the following piezoelectric characteristics were measured based on the amount of displacement of the element.
  • the piezoelectric constant d 31 the piezoelectric constant d 31 , the dielectric constant ⁇ r , the piezoelectric efficiency d 31 / ⁇ r , and the temperature change rate ⁇ r of the dielectric constant under 1 kV/mm AC drive.
  • Table 1 shows the results. Impedance analyzer 4294A manufactured by Agilent was used for all measurements, piezoelectric constant d 31 at 20° C. was determined by the resonance-antiresonance method, and dielectric constant ⁇ r at 20° C. was calculated from capacitance.
  • the rate of change in relative permittivity with temperature ⁇ r ⁇ TC is obtained by measuring the capacitance in a constant temperature bath by the same method, obtaining the relative permittivity at 0° C. or higher and 80° C. or lower. It was obtained by dividing the maximum value of relative permittivity ⁇ r by the minimum value of relative permittivity ⁇ r .
  • the Ca substitution rate is 0.5 mol% or more and 1.75 mol% or less
  • the Zr substitution rate is 0.5 mol% or more and 1.75 mol% or less
  • MnCO3 is 0.15 parts by weight or more and 5 parts by weight.
  • the piezoelectric laminated element can obtain a higher piezoelectric efficiency d 31 / ⁇ r , and in particular, sample No. 1 with a replacement ratio of Ca: 1.0 mol % and Zr: 1.0 mol. 1, the highest value could be obtained.
  • the a/b ratio is The smaller the piezoelectric laminate element, the higher the piezoelectric efficiency d 31 / ⁇ r and the smaller the temperature change rate ⁇ r ⁇ TC of the dielectric constant.

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Abstract

Provided is a piezoelectric layered element with which optimal piezoelectric properties can be obtained even when using a thin-layer layered structure that includes an internal electrode layer having Ni as the main component.　This piezoelectric layered element is characterized by comprising a plurality of piezoelectric ceramic layers, an internal electrode layer that is provided between the piezoelectric ceramic layers, and an external electrode that is electrically connected to the internal electrode layer, wherein the piezoelectric ceramic layers are each composed of an Mn-containing piezoelectric material and an oxide including Ba, Ca, Ti, and Zr, the molar ratio x of Ca to the sum of Ba and Ca is 0.005 ≤ x ≤ 0.0175, the molar ratio y of Zr to the sum of Ti and Zr is 0.005 ≤ y ≤ 0.0175, the amount of Mn relative to 100 parts by weight of the oxide is 0.15 parts by weight to 5.0 parts by weight, inclusive, in terms of MnO, and Ni is the main component of the internal electrode layer.

Description

圧電積層素子Piezoelectric laminated element
　本発明は、圧電積層素子に関する。 The present invention relates to a piezoelectric laminated element.
　ペロブスカイト型金属酸化物である圧電材料として、チタン酸バリウムが知られている。また、その特性を改良する目的で、チタン酸バリウムの組成をベースとした材料開発が行われており、一例として、チタン酸バリウムのＡサイトを一部Ｃａに置換し、更にＭｎ、Ｆｅ、又はＣｕを添加した圧電素子等が開示されている。これらの圧電素子等は、チタン酸バリウムに比べて機械的品質係数に優れるものの、圧電特性が低いため、素子の駆動に高い電圧を要する。 Barium titanate is known as a piezoelectric material that is a perovskite-type metal oxide. In addition, for the purpose of improving its properties, material development based on the composition of barium titanate is being carried out. A piezoelectric element or the like to which Cu is added is disclosed. Although these piezoelectric elements and the like are superior in mechanical quality factor to barium titanate, they have low piezoelectric characteristics, and therefore require a high voltage to drive the elements.
　圧電特性を改良することを目的として、特許文献１では、Ｂａ、Ｃａ、Ｔｉ、Ｚｒを含む酸化物、及びＭｎを含有し、Ｂａ、Ｃａ含有モル数の和に対してＣａモル比ｘが０．０２≦ｘ≦０．３０、Ｔｉ、Ｚｒ含有モル数の和に対してＺｒモル比ｙが０．０２≦ｙ≦０．０９５かつｙ≦ｘであり、Ｔｉ、Ｚｒモル和に対するＢａ、Ｃａモル和の比ａが１．００≦ａ≦１．０１であり、Ｂａ、Ｃａ、Ｔｉ、Ｚｒを含む酸化物１００重量部に対してＭｎを金属換算で０．０２重量部以上０．４０重量部以下含む圧電材料が開示されている。 For the purpose of improving the piezoelectric properties, in Patent Document 1, an oxide containing Ba, Ca, Ti, and Zr, and Mn are contained, and the Ca molar ratio x is 0 with respect to the sum of the Ba and Ca containing molar numbers. .02 ≤ x ≤ 0.30, Zr molar ratio y is 0.02 ≤ y ≤ 0.095 and y ≤ x with respect to the sum of the number of moles containing Ti and Zr, and Ba and Ca with respect to the sum of Ti and Zr moles The molar sum ratio a is 1.00 ≤ a ≤ 1.01, and Mn is 0.02 parts by weight or more and 0.40 parts by weight in terms of metal with respect to 100 parts by weight of the oxide containing Ba, Ca, Ti, and Zr A piezoelectric material is disclosed that includes:
特許第６０８０３９７号公報Japanese Patent No. 6080397
　特許文献１では、大気雰囲気下での圧電材料の評価について多数述べられており、実施例において、高い圧電定数ｄ３１が得られる領域としてＡサイト成分Ｃａ：５ｍｏｌ％～１５ｍｏｌ％、Ｂサイト成分Ｚｒ：５ｍｏｌ％～１５ｍｏｌ％が好適であり、特にアクチュエータ用途としてはＣａ：１４ｍｏｌ％～１７．５ｍｏｌ％、Ｚｒ：５．５ｍｏｌ％～９ｍｏｌ％が好適であると開示されている。 In Patent Document 1, many evaluations of piezoelectric materials in an air atmosphere are described. : 5 mol % to 15 mol % is suitable, and particularly for actuator applications, Ca: 14 mol % to 17.5 mol % and Zr: 5.5 mol % to 9 mol % are disclosed.
　一般にこれらのセラミック組成を有する圧電材料を圧電素子に使用する場合、内部電極層を有する積層構造体にすることで素子の駆動電圧を下げることができるが、この内部電極層にＮｉ等の卑金属材料を用いる場合は、積層構造体の共焼結過程で電極金属層の酸化を防ぐために還元雰囲気が必要となる。このとき、雰囲気中の酸素分圧の違いによる焼結後のセラミック組成の変化や、内部電極層中のＮｉ成分がセラミック層内へ侵入及び拡散することにより、薄層の積層構造体では所望の圧電特性が得られない。 In general, when a piezoelectric material having such a ceramic composition is used for a piezoelectric element, the driving voltage of the element can be lowered by forming a laminated structure having internal electrode layers. is used, a reducing atmosphere is required to prevent oxidation of the electrode metal layer during the co-sintering process of the laminated structure. At this time, due to changes in the ceramic composition after sintering due to differences in the oxygen partial pressure in the atmosphere, and Ni components in the internal electrode layers penetrating and diffusing into the ceramic layers, the thin layered structure may not produce the desired results. Piezoelectric characteristics cannot be obtained.
　更に特許文献１の組成では、Ｚｒモル比の増加に伴い、０℃以上１００℃以下に存在するペロブスカイト型金属酸化物の二つの結晶相転移発生温度が接近することにより、室温以上１００℃付近以下までの比誘電率が激しく増加し、圧電素子の静電容量が増大する。このような使用時の温度上昇に依る圧電素子の静電容量の増大は、省電力性を求められる携帯機器等の用途において駆動初期電流の増加に繋がるため、望ましくない。 Furthermore, in the composition of Patent Document 1, as the Zr molar ratio increases, the two crystal phase transition temperatures of the perovskite-type metal oxide present at 0°C or higher and 100°C or lower approach each other. The relative permittivity of up to 100% sharply increases, and the capacitance of the piezoelectric element increases. An increase in the capacitance of the piezoelectric element due to a rise in temperature during use is undesirable because it leads to an increase in the initial drive current in applications such as portable devices that require power saving.
　以上の事から、Ｎｉを主成分とする内部電極層を使用した薄層積層構造体において、最適な圧電特性が得られる組成の圧電材料が必要であると考えられる。 From the above, it is considered that a piezoelectric material with a composition that can obtain optimum piezoelectric characteristics is necessary in a thin-layer laminated structure using internal electrode layers containing Ni as a main component.
　本発明は上記の問題を解決するためになされたものであり、Ｎｉを主成分とする内部電極層を使用した薄層積層構造体とした場合においても、最適な圧電特性が得られる圧電積層素子を提供することを目的とする。 SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a piezoelectric multilayer element capable of obtaining optimum piezoelectric characteristics even in the case of a thin-layer multilayer structure using internal electrode layers containing Ni as a main component. intended to provide
　本発明の圧電積層素子は、複数の圧電体セラミック層と、上記圧電体セラミック層間に設けられた内部電極層と、上記内部電極層に電気的に接続された外部電極とを備え、上記圧電体セラミック層が、Ｂａ、Ｃａ、Ｔｉ及びＺｒを含む酸化物、並びにＭｎを含有する圧電材料で構成され、上記Ｂａ及び上記Ｃａの和に対する上記Ｃａのモル比ｘが０．００５≦ｘ≦０．０１７５であり、上記Ｔｉ及び上記Ｚｒの和に対する上記Ｚｒのモル比ｙが０．００５≦ｙ≦０．０１７５であり、上記酸化物１００重量部に対する上記Ｍｎの含有量が、ＭｎＯ換算で０．１５重量部以上５．０重量部以下であり、上記内部電極層がＮｉを主成分とする、ことを特徴とする。 A piezoelectric multilayer element of the present invention includes a plurality of piezoelectric ceramic layers, internal electrode layers provided between the piezoelectric ceramic layers, and external electrodes electrically connected to the internal electrode layers, and comprises the piezoelectric body The ceramic layer is composed of an oxide containing Ba, Ca, Ti and Zr and a piezoelectric material containing Mn, and the molar ratio x of Ca to the sum of Ba and Ca is 0.005≦x≦0.005. 0175, the molar ratio y of the Zr to the sum of the Ti and the Zr is 0.005≦y≦0.0175, and the content of the Mn with respect to 100 parts by weight of the oxide is 0.01 in terms of MnO. It is characterized in that it is 15 parts by weight or more and 5.0 parts by weight or less, and the internal electrode layer contains Ni as a main component.
　本発明によれば、Ｎｉを主成分とする内部電極層を使用した薄層積層構造体とした場合においても、最適な圧電特性が得られる圧電積層素子を提供することができる。 According to the present invention, it is possible to provide a piezoelectric laminated element capable of obtaining optimum piezoelectric characteristics even in the case of forming a thin-layer laminated structure using internal electrode layers containing Ni as a main component.
図１Ａは、本発明の圧電積層素子の構成の一例を模式的に示す断面図である。FIG. 1A is a cross-sectional view schematically showing an example of the configuration of the piezoelectric laminated element of the present invention. 図１Ｂは、図１Ａの圧電積層素子の平面図である。FIG. 1B is a plan view of the piezoelectric laminate of FIG. 1A.
　以下、本発明の圧電積層素子について説明する。
　しかしながら、本発明は、以下の構成に限定されるものではなく、本発明の要旨を変更しない範囲において適宜変更して適用することができる。なお、以下において記載する個々の望ましい構成を２つ以上組み合わせたものもまた本発明である。 The piezoelectric laminated element of the present invention will be described below.
However, the present invention is not limited to the following configurations, and can be appropriately modified and applied without changing the gist of the present invention. Combinations of two or more of the individual desirable configurations described below are also part of the present invention.
　本発明の圧電積層素子は、複数の圧電体セラミック層を備える。上記圧電体セラミック層は、Ｂａ、Ｃａ、Ｔｉ及びＺｒを含む酸化物、並びにＭｎを含有する圧電材料で構成されている。 The piezoelectric laminated element of the present invention includes a plurality of piezoelectric ceramic layers. The piezoelectric ceramic layer is composed of an oxide containing Ba, Ca, Ti and Zr, and a piezoelectric material containing Mn.
　本発明において、上記酸化物は、下記一般式（１）：
（Ｂａ１－ｘＣａｘ）ａ（Ｔｉ１－ｙＺｒｙ）ｂＯ３　　（１）
で表わされるペロブスカイト型金属酸化物であり、上記一般式（１）中、ｘが０．００５≦ｘ≦０．０１７５であり、ｙが０．００５≦ｙ≦０．０１７５である。 In the present invention, the oxide has the following general formula (1):
(Ba 1-x Ca x ) a (Ti 1-y Zr y ) b O 3 (1)
wherein x satisfies 0.005≦x≦0.0175 and y satisfies 0.005≦y≦0.0175 in the general formula (1).
　本発明において、ペロブスカイト型金属酸化物とは、理想的には立方晶系であるペロブスカイト型構造を持つ金属酸化物を指す。ペロブスカイト型構造を持つ金属酸化物は、一般にＡＢＯ３の化学式で表現される。ペロブスカイト型金属酸化物において、元素Ａ、Ｂは各々イオンの形でＡサイト、Ｂサイトと呼ばれる単位格子の特定の位置を占める。例えば、立方晶系の単位格子であれば、Ａ元素は立方体の頂点、Ｂ元素は体心に位置する。Ｏ元素は酸素の陰イオンとして立方体の面心位置を占める。 In the present invention, a perovskite-type metal oxide refers to a metal oxide having a perovskite-type structure, which is ideally a cubic system. Metal oxides with a perovskite structure are generally represented by the chemical formula ABO3 . In the perovskite-type metal oxide, the elements A and B occupy specific positions in the unit lattice called A sites and B sites in the form of ions, respectively. For example, in a cubic system unit cell, the A element is located at the vertices of the cube, and the B element is located at the center of the body. The O element occupies the face-center position of the cube as an anion of oxygen.
　上記一般式（１）で表わされるペロブスカイト型金属酸化物は、Ａサイトに位置する元素がＢａとＣａであり、Ｂサイトに位置する元素がＴｉとＺｒであることを意味する。ただし、一部のＢａとＣａがＢサイトに位置していてもよく、一部のＴｉとＺｒがＡサイトに位置していてもよい。 The perovskite-type metal oxide represented by the above general formula (1) means that the elements located at the A site are Ba and Ca, and the elements located at the B site are Ti and Zr. However, part of Ba and Ca may be located at the B site, and part of Ti and Zr may be located at the A site.
　本発明において、上記酸化物の上記Ｂａ及び上記Ｃａの和に対する上記Ｃａのモル比ｘが０．００５≦ｘ≦０．０１７５であり、上記Ｔｉ及び上記Ｚｒの和に対する上記Ｚｒのモル比ｙが０．００５≦ｙ≦０．０１７５である。Ｂａに対するＣａの置換量及びＴｉに対するＺｒの置換量を上記範囲とすることで、「斜方晶と正方晶との相転移」が生じる温度及び「正方晶と立方晶との相転移」が生じる温度を、１０℃未満かつ８０℃を超える温度とすることができるため、１０℃以上８０℃以下の温度域における圧電積層素子の比誘電率の温度変化率が小さくなる。 In the present invention, the molar ratio x of Ca to the sum of Ba and Ca in the oxide is 0.005 ≤ x ≤ 0.0175, and the molar ratio y of Zr to the sum of Ti and Zr is 0.005≤y≤0.0175. By setting the amount of Ca substituted for Ba and the amount of Zr substituted for Ti within the above ranges, the temperature at which "phase transition between orthorhombic and tetragonal" occurs and "phase transition between tetragonal and cubic" occur. Since the temperature can be less than 10.degree. C. and more than 80.degree.
　本発明の圧電積層素子がより高い圧電効率を得られるため、上記モル比ｘと上記モル比ｙとが同じ値であることが好ましく、ｘ＝０．０１かつｙ＝０．０１であることがより好ましい。本明細書において、圧電効率は、圧電定数ｄ３１を比誘電率εｒで除した値である。 In order to obtain higher piezoelectric efficiency in the piezoelectric laminated element of the present invention, the molar ratio x and the molar ratio y are preferably the same value, and x=0.01 and y=0.01. more preferred. In this specification, the piezoelectric efficiency is the value obtained by dividing the piezoelectric constant d31 by the relative dielectric constant εr .
　上記一般式（１）における、Ａサイトの元素とＢサイトの元素とのモル比（ａ／ｂ）は、通常１．０００であるが、１．０００以上１．０１０以下であっても、上記酸化物がペロブスカイト型構造を主相としていれば、本発明の範囲に含まれる。従って、上記Ｔｉ及び上記Ｚｒの和に対する上記Ｂａ及び上記Ｃａの和のモル比（ａ／ｂ）は、１．０００以上１．０１０以下であってもよい。好ましくは、上記モル比（ａ／ｂ）は、１．００３以上１．００７以下である。
　上記酸化物の組成を測定する手段は特に限定されず、例えば蛍光Ｘ線分析（ＸＲＦ）、誘導結合プラズマ（ＩＣＰ）発光分光分析、原子吸光分析等が挙げられる。いずれの手段においても、上記酸化物に含まれる各元素の重量比及び組成比を算出できる。 In general formula (1), the molar ratio (a/b) of the element at the A site and the element at the B site is usually 1.000. As long as the oxide has a perovskite structure as the main phase, it falls within the scope of the present invention. Therefore, the molar ratio (a/b) of the sum of Ba and Ca to the sum of Ti and Zr may be 1.000 or more and 1.010 or less. Preferably, the molar ratio (a/b) is 1.003 or more and 1.007 or less.
The means for measuring the composition of the oxide is not particularly limited, and examples thereof include X-ray fluorescence spectroscopy (XRF), inductively coupled plasma (ICP) emission spectroscopy, and atomic absorption spectroscopy. By either means, the weight ratio and composition ratio of each element contained in the oxide can be calculated.
　上記圧電材料において、上記酸化物１００重量部に対する上記Ｍｎの含有量は、ＭｎＯ換算で０．１５重量部以上５．０重量部以下である。上記Ｍｎの含有量は、例えばＸＲＦにより上記圧電材料を測定して得られたＢａ、Ｃａ、Ｔｉ、Ｚｒ及びＭｎ等の各金属の含有量から、上記酸化物を構成するＢａ、Ｃａ、Ｔｉ及びＺｒを酸化物換算し、その総重量を１００重量部としたときに対するＭｎＯの重量との比によって求められた値を表す。 In the piezoelectric material, the content of Mn with respect to 100 parts by weight of the oxide is 0.15 parts by weight or more and 5.0 parts by weight or less in terms of MnO. The content of Mn is determined from the content of each metal such as Ba, Ca, Ti, Zr and Mn obtained by measuring the piezoelectric material by XRF, for example, and Ba, Ca, Ti and It represents a value obtained from the ratio of the weight of MnO to the total weight of 100 parts by weight of Zr converted to oxide.
　Ｍｎの含有量がＭｎＯ換算で０．１５重量部未満であると、圧電積層素子の駆動に必要な分極処理の効果が充分でなくなる。一方、Ｍｎの含有量がＭｎＯ換算で５．０重量部より多くなると、圧電材料中の一般式（１）で表わされる金属酸化物の含有量が少なくなるため、圧電効率が充分でなくなる。 If the Mn content is less than 0.15 parts by weight in terms of MnO, the effect of the polarization treatment necessary for driving the piezoelectric laminated element will not be sufficient. On the other hand, when the Mn content exceeds 5.0 parts by weight in terms of MnO, the content of the metal oxide represented by the general formula (1) in the piezoelectric material decreases, resulting in insufficient piezoelectric efficiency.
　上記圧電材料は、更に副成分として、焼結助剤や添加剤を含んでいてもよい。焼結助剤としては、例えばＳｉが挙げられる。Ｓｉの含有量は特に限定されないが、圧電材料を低温で焼成することができ、内部電極層から材料が拡散することを防止するため、上記酸化物１００重量部に対して、ＳｉＯ２換算で、０．２重量部以上１．０重量部以下が好ましい。 The piezoelectric material may further contain sintering aids and additives as subcomponents. Examples of sintering aids include Si. The content of Si is not particularly limited, but in order to allow the piezoelectric material to be fired at a low temperature and to prevent the material from diffusing from the internal electrode layer, the content of Si is calculated as SiO 2 with respect to 100 parts by weight of the oxide, 0.2 parts by weight or more and 1.0 parts by weight or less is preferable.
　添加剤としては、例えばＭｇが挙げられる。Ｍｇの含有量は特に限定されないが、本発明の圧電積層素子の製品としての信頼性を担保するため、上記酸化物１００重量部に対して、ＭｇＯ換算で、０．１重量部以上０．５重量部以下が好ましい。 Additives include, for example, Mg. The content of Mg is not particularly limited, but in order to ensure reliability as a product of the piezoelectric laminated element of the present invention, it should be 0.1 parts by weight or more and 0.5 parts by weight in terms of MgO with respect to 100 parts by weight of the oxide. Part by weight or less is preferred.
　また、上記圧電材料は、市販原料に不可避成分として含まれる程度の量のＳｒ、ＮｂやＨｆ等の金属を含んでいてもよい。 In addition, the piezoelectric material may contain metals such as Sr, Nb, and Hf in amounts that are included as inevitable components in commercially available raw materials.
　本発明の圧電積層素子は、Ｎｉを主成分とする内部電極層を備える。上記内部電極層がＮｉを主成分にするとは、内部電極層を構成する材料でＮｉの含有量が最も多く、かつ上記内部電極層がＮｉを５０重量％以上含むことを意味する。上記内部電極層のＮｉ含有量は１００重量％であってもよい。Ｎｉ以外に内部電極層に用い得る材料としては、例えば、Ｔｉ、Ｐｔ、Ｔａ、Ｉｒ、Ｓｒ、Ｉｎ、Ｓｎ、Ａｕ、Ａｌ、Ｆｅ、Ｃｒ、Ｎｉ、Ｐｄ、Ａｇ、Ｃｕ等の、圧電積層素子に通常用いられている金属及びこれらの化合物を挙げることができる。 The piezoelectric laminated element of the present invention includes internal electrode layers containing Ni as a main component. The fact that the internal electrode layers contain Ni as a main component means that the internal electrode layers contain the largest amount of Ni among the materials constituting the internal electrode layers, and that the internal electrode layers contain Ni in an amount of 50% by weight or more. The Ni content of the internal electrode layers may be 100% by weight. Materials other than Ni that can be used for the internal electrode layers include piezoelectric laminated elements such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, and Cu. metals and their compounds commonly used in
　上記内部電極層は、２種以上の材料を積層してなるものであってもよい。本発明の圧電積層素子に複数の内部電極層が設けられている場合、全ての内部電極層が同じ材料で構成されていてもよいし、それぞれ異なる材料であってもよい。 The internal electrode layer may be formed by laminating two or more kinds of materials. When the piezoelectric laminated element of the present invention is provided with a plurality of internal electrode layers, all the internal electrode layers may be made of the same material, or may be made of different materials.
　本発明の圧電積層素子は、複数の圧電体セラミック層と、上記圧電体セラミック層間に設けられた内部電極層と、上記内部電極層に電気的に接続された外部電極とを備えている。
　本発明の圧電積層素子は、圧電体セラミック層が上記圧電材料で構成されていることにより、Ｎｉを主成分とする内部電極層を共焼結するために還元雰囲気下で焼成を行って製造された場合でも、高い圧電定数ｄ３１及び高い圧電効率を有する。 A piezoelectric laminated element of the present invention includes a plurality of piezoelectric ceramic layers, internal electrode layers provided between the piezoelectric ceramic layers, and external electrodes electrically connected to the internal electrode layers.
The piezoelectric laminated element of the present invention is manufactured by firing under a reducing atmosphere in order to co-sinter the internal electrode layers containing Ni as a main component, since the piezoelectric ceramic layers are made of the above piezoelectric material. It has a high piezoelectric constant d31 and a high piezoelectric efficiency even when
　Ｎｉを内部電極層とする圧電積層素子において、圧電体セラミック層が薄いと内部電極層に含まれるＮｉの拡散が増加するが、上記圧電材料の組成では、圧電体セラミック層の厚さが３０μｍ以下であっても圧電定数ｄ３１の低下が小さいため、低い駆動電圧であっても大きな変位量を得ることができる。上記圧電体セラミック層の１層あたりの平均厚さは特に限定されないが、本発明の圧電積層素子の構成は、上記圧電体セラミック層の１層あたりの平均厚さが３０μｍ以下である場合に好適である。上記圧電体セラミック層の１層あたりの平均厚さは、好ましくは１０μｍ以上である。 In a piezoelectric laminated element having Ni as internal electrode layers, if the piezoelectric ceramic layers are thin, the diffusion of Ni contained in the internal electrode layers increases. Since the decrease in the piezoelectric constant d31 is small even at , a large amount of displacement can be obtained even with a low driving voltage. Although the average thickness of each piezoelectric ceramic layer is not particularly limited, the structure of the piezoelectric laminated element of the present invention is suitable when the average thickness of each piezoelectric ceramic layer is 30 μm or less. is. The average thickness of each piezoelectric ceramic layer is preferably 10 μm or more.
　ここで、圧電体セラミック層の厚みとは、内部電極層の間にある圧電体セラミック層の厚みを意味する。
　圧電体セラミック層の厚みは、以下のようにして定める。 Here, the thickness of the piezoelectric ceramic layer means the thickness of the piezoelectric ceramic layer between the internal electrode layers.
The thickness of the piezoelectric ceramic layer is determined as follows.
　まず、圧電積層素子の長さ（Ｌ）方向の中心を通る、幅（Ｗ）方向及び積層（Ｔ）方向の断面（ＷＴ断面）を研磨により露出させる。必要に応じて、研磨で引き伸ばされた内部電極層を除去するために研磨面にエッチング処理を行う。そして、露出させた断面を走査型電子顕微鏡により観察する。 First, a section (WT section) in the width (W) direction and lamination (T) direction passing through the center of the piezoelectric laminated element in the length (L) direction is exposed by polishing. If necessary, the polished surface is etched to remove the internal electrode layer stretched by polishing. Then, the exposed cross section is observed with a scanning electron microscope.
　圧電体セラミック層及び内部電極層の積層方向Ｔに延びてかつ積層体の中心を通る直線Ｌｃを引く。次に、直線Ｌｃと平行な複数の直線を等間隔に引く。隣り合う直線の間隔は、測定しようとする圧電体セラミック層の厚みの５倍以上１０倍以下程度で決めればよい。また、直線Ｌｃの両側に同じ本数の直線を引く。すなわち、直線Ｌｃを合わせて奇数本の直線を引く。例えば、直線Ｌｃを合わせて５本の直線を引く。 A straight line Lc extending in the lamination direction T of the piezoelectric ceramic layers and the internal electrode layers and passing through the center of the laminate is drawn. Next, a plurality of straight lines parallel to the straight line Lc are drawn at regular intervals. The interval between adjacent straight lines may be determined to be about 5 to 10 times the thickness of the piezoelectric ceramic layer to be measured. Also, the same number of straight lines are drawn on both sides of the straight line Lc. That is, an odd number of straight lines are drawn by combining the straight lines Lc. For example, five straight lines are drawn by combining the straight lines Lc.
　次に、直線Ｌｃ等の各直線上において、圧電体セラミック層の厚みを測定する。ただし、各直線上において、内部電極層が欠損して、この内部電極層を挟む圧電体セラミック層同士が繋がっている場合、又は、測定位置の拡大像が不明瞭である場合は、更に直線Ｌｃから離れた直線上において、厚み又は距離を測定する。これらの平均値を圧電体セラミック層の厚みとする。 Next, the thickness of the piezoelectric ceramic layer is measured on each straight line such as the straight line Lc. However, on each straight line, if the internal electrode layer is missing and the piezoelectric ceramic layers sandwiching this internal electrode layer are connected to each other, or if the enlarged image of the measurement position is unclear, then the straight line Lc Measure the thickness or distance on a straight line away from Let the average value of these values be the thickness of the piezoelectric ceramic layer.
　本発明の圧電積層素子において、圧電体セラミック層の数は２以上であればよく、例えば１０以上であってもよい。 In the piezoelectric laminated element of the present invention, the number of piezoelectric ceramic layers may be 2 or more, for example, 10 or more.
　本発明の圧電積層素子は、温度による比誘電率の変動が小さく、圧電体セラミック層が３０μｍ以下である薄層積層構造体であっても、１０℃以上８０℃以下の温度範囲で高い圧電特性が得られるため、一般的な携帯機器等の使用に適した省電力性を併せ持った圧電積層素子として好適である。 The piezoelectric laminated element of the present invention has a small change in relative dielectric constant due to temperature, and has high piezoelectric characteristics in the temperature range of 10° C. to 80° C. even if it is a thin layer laminated structure in which the piezoelectric ceramic layer has a thickness of 30 μm or less. can be obtained, it is suitable as a piezoelectric laminated element having power saving properties suitable for use in general portable equipment and the like.
　以下では、図１Ａ及び図１Ｂを参照して本発明の圧電積層素子の構成について説明する。
　図１Ａは、本発明の圧電積層素子の構成の一例を模式的に示す断面図である。図１Ｂは、図１Ａの圧電積層素子の平面図である。 The configuration of the piezoelectric laminated element of the present invention will be described below with reference to FIGS. 1A and 1B.
FIG. 1A is a cross-sectional view schematically showing an example of the configuration of the piezoelectric laminated element of the present invention. FIG. 1B is a plan view of the piezoelectric laminate of FIG. 1A.
　図１Ａ及び図１Ｂに示す圧電積層素子１０は、圧電セラミック素体１と、圧電セラミック素体１の表面に設けられた外部電極４ａ及び４ｂと、を備える。図１Ａ及び図１Ｂでは、外部電極４ａ及び４ｂは、圧電セラミック素体１の両端部に設けられ、駆動層を増やすために、外部電極４ｂは、圧電セラミック素体１の表裏にも延びている。外部電極４ａ及び４ｂは、例えば、上述の内部電極層と同じ材料から構成される。 A piezoelectric laminated element 10 shown in FIGS. 1A and 1B includes a piezoelectric ceramic body 1 and external electrodes 4 a and 4 b provided on the surface of the piezoelectric ceramic body 1 . In FIGS. 1A and 1B, the external electrodes 4a and 4b are provided at both ends of the piezoelectric ceramic body 1, and the external electrodes 4b extend to the front and back of the piezoelectric ceramic body 1 in order to increase the driving layers. . The external electrodes 4a and 4b are made of, for example, the same material as the internal electrode layers described above.
　図１Ａに示すように、圧電セラミック素体１では、圧電体セラミック層２ａ、２ｂ、２ｃ、２ｄ、２ｅ、２ｆ、２ｇ、２ｈ、２ｉ及び２ｊと内部電極層３ａ、３ｂ、３ｃ、３ｄ、３ｅ、３ｆ、３ｇ、３ｈ及び３ｉとが交互に積層されている。圧電体セラミック層２ａ、２ｂ、２ｃ、２ｄ、２ｅ、２ｆ、２ｇ、２ｈ、２ｉ及び２ｊは、上述した圧電材料から構成されている。内部電極層３ａ、３ｂ、３ｃ、３ｄ、３ｅ、３ｆ、３ｇ、３ｈ及び３ｉは、Ｎｉを主成分とする導電性材料から構成されている。 As shown in FIG. 1A, in the piezoelectric ceramic body 1, piezoelectric ceramic layers 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i and 2j and internal electrode layers 3a, 3b, 3c, 3d and 3e are arranged. , 3f, 3g, 3h and 3i are alternately stacked. The piezoelectric ceramic layers 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i and 2j are made of the piezoelectric material described above. The internal electrode layers 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h and 3i are made of a conductive material containing Ni as a main component.
　圧電積層素子１０においては、内部電極層３ａ、３ｃ、３ｅ、３ｇ及び３ｉの一端が一方の外部電極４ａと電気的に接続され、内部電極層３ｂ、３ｄ、３ｆ及び３ｈの一端が他方の外部電極４ｂと電気的に接続されている。 In the piezoelectric laminated element 10, one end of the internal electrode layers 3a, 3c, 3e, 3g, and 3i is electrically connected to one external electrode 4a, and one end of the internal electrode layers 3b, 3d, 3f, and 3h is electrically connected to the other external electrode. It is electrically connected to the electrode 4b.
　本発明の圧電積層素子は、例えば以下の方法により製造される。 The piezoelectric laminated element of the present invention is manufactured, for example, by the following method.
　まず、圧電材料に含有される酸化物及びＭｎとなるセラミック原料として、酸化物や炭酸塩などを高温で反応させる固相法により作製した原料粉末や、アルコキシド法あるいは水熱合成法などの湿式合成法により作製した原料粉末を準備する。なお、焼結助剤や添加剤などは、酸化物や炭酸塩などの粉末以外に、アルコキシド、有機金属などの溶液を用いることもできる。 First, as a ceramic raw material that becomes the oxide and Mn contained in the piezoelectric material, raw material powder prepared by a solid phase method in which oxides, carbonates, etc. are reacted at high temperature, and wet synthesis such as an alkoxide method or a hydrothermal synthesis method. A raw material powder prepared according to the method is prepared. As the sintering aids and additives, in addition to powders of oxides and carbonates, solutions of alkoxides and organic metals can also be used.
　その後、準備したセラミック原料を所定の組成比率に秤量し混合した後、有機バインダー、可塑剤や溶媒を加えてスラリー化し、シート状に成形してグリーンシートを得る。次いで、一部のグリーンシートの一面にＮｉを主成分とする内部電極層を形成する。なお、内部電極層を形成する方法は、スクリーン印刷などによる形成でも、蒸着、めっき法による形成でも構わない。 After that, after weighing and mixing the prepared ceramic raw materials in a predetermined composition ratio, an organic binder, a plasticizer, and a solvent are added to form a slurry, which is formed into a sheet to obtain a green sheet. Next, an internal electrode layer containing Ni as a main component is formed on one surface of some of the green sheets. The method for forming the internal electrode layers may be formation by screen printing or the like, vapor deposition, or plating.
　その後、これらのグリーンシートを組み合わせて必要枚数積層し、圧着して積層体とする。そして、この積層体を還元雰囲気中、所定の温度（例えば、１２００℃以上、１３００℃以下）にて焼成し、セラミック積層体を得る。 After that, these green sheets are combined, stacked in the required number, and crimped to form a laminate. Then, this laminate is fired at a predetermined temperature (for example, 1200° C. or higher and 1300° C. or lower) in a reducing atmosphere to obtain a ceramic laminate.
　その後、セラミック積層体の両端面に、内部電極層と電気的に接続するように、外部電極を形成する。外部電極がセラミック積層体の表面及び裏面に設けられていてもよい。一般的に、外部電極は、積層体を焼成して得られたセラミック積層体に、材料となる金属粉末ペーストを塗布して更に焼き付けることによって形成されるが、積層体の焼成前に金属粉末ペーストを塗布して、セラミック積層体と同時に形成することもできる。また、スパッタにより外部電極を形成することもできる。 After that, external electrodes are formed on both end surfaces of the ceramic laminate so as to be electrically connected to the internal electrode layers. External electrodes may be provided on the front and back surfaces of the ceramic laminate. In general, the external electrodes are formed by applying a metal powder paste as a material to a ceramic laminate obtained by firing the laminate and then baking the laminate. can be applied and formed simultaneously with the ceramic laminate. Alternatively, the external electrodes can be formed by sputtering.
　その後、所定の分極処理を行う。以上により、本発明の圧電積層素子が得られる。 After that, a predetermined polarization process is performed. As described above, the piezoelectric laminated element of the present invention is obtained.
　以下、本発明の圧電積層素子をより具体的に開示した実施例を示す。なお、本発明は、これらの実施例のみに限定されない。
　なお、圧電積層素子における圧電材料の組成は、材料である混合原料粉末、ＭｎＣＯ３、ＭｇＣＯ３、ＳｉＯ２の混合物の組成と同じである。 Hereinafter, examples that more specifically disclose the piezoelectric laminated element of the present invention will be shown. It should be noted that the present invention is not limited only to these examples.
The composition of the piezoelectric material in the piezoelectric laminated element is the same as the composition of the mixture of the mixed raw material powder, MnCO 3 , MgCO 3 and SiO 2 .
　仮焼済み酸化物原料粉末として、ＢａＴｉＯ３、ＣａＴｉＯ３及びＢａＺｒＯ３を準備した。圧電材料が表１に示す組成比となるように、混合原料粉末を調製した。表１中のａ／ｂ比は、Ｔｉ及びＺｒの和に対するＢａ及びＣａの和のモル比（ａ／ｂ）である。なお、試料番号Ｎｏ．１～Ｎｏ．１１は、本発明の組成であり、Ｎｏ．１２～Ｎｏ．１７は、比較例の組成である。 BaTiO 3 , CaTiO 3 and BaZrO 3 were prepared as calcined oxide raw material powders. A mixed raw material powder was prepared so that the piezoelectric material had a composition ratio shown in Table 1. The a/b ratio in Table 1 is the molar ratio (a/b) of the sum of Ba and Ca to the sum of Ti and Zr. In addition, sample number No. 1 to No. No. 11 is the composition of the present invention. 12 to No. No. 17 is the composition of the comparative example.
　次いで、表１に示す試料番号Ｎｏ．１～Ｎｏ．１７の各組成を有する混合原料粉末１００重量部に対して、ＭｎＣＯ３を０．００重量部以上１５．００重量部以下、ＭｇＣＯ３を０．２４重量部、ＳｉＯ２を０．８重量部、ポリビニルブチラール(ＰＶＢ)樹脂１０重量部、トルエン１５０重量部及びエタノール１５０重量部を加えたのち、ボールミルで粉砕混合してセラミックスラリーを調製した。このセラミックスラリーをドクターブレードにより塗工後乾燥して、厚さ１０μｍのグリーンシートを得た。更に一部のグリーンシートには、Ｎｉ金属ぺースト印刷により所定の形状の表面電極を形成し、これらのシートを組み合わせて、焼結後の内部電極層間の圧電体セラミック層の厚さ３０μｍ、圧電体セラミック層が全１０層となるように積層圧着した構造体を得た。この構造体を５ｍｍ×２０ｍｍに切り出した後、脱脂処理及び還元雰囲気中１２５０℃での焼成処理を行った。更に焼成処理後の圧電セラミック素体の両端面に外部電極を形成して、内部電極層が交互にいずれか一方の外部電極に接続される圧電積層素子構造とした後、両極に各層２ｋＶ／ｍｍに相当する電圧を印加して分極処理を行った。この分極済み圧電積層素子に１ｋＶ／ｍｍの交流を印加して駆動し、素子変位量に基づいて以下の圧電特性を測定した。 Next, the sample No. shown in Table 1 was tested. 1 to No. 0.00 parts by weight or more and 15.00 parts by weight or less of MnCO3 , 0.24 parts by weight of MgCO3 , 0.8 parts by weight of SiO2 , and After adding 10 parts by weight of polyvinyl butyral (PVB) resin, 150 parts by weight of toluene and 150 parts by weight of ethanol, the mixture was pulverized and mixed with a ball mill to prepare a ceramic slurry. This ceramic slurry was applied with a doctor blade and then dried to obtain a green sheet with a thickness of 10 μm. Further, on some of the green sheets, surface electrodes of a predetermined shape are formed by Ni metal paste printing. A structure was obtained in which a total of 10 ceramic layers were laminated and press-bonded. After cutting this structure into a size of 5 mm×20 mm, it was degreased and fired at 1250° C. in a reducing atmosphere. Furthermore, external electrodes are formed on both end surfaces of the piezoelectric ceramic body after the firing treatment, and a piezoelectric laminated element structure in which the internal electrode layers are alternately connected to one of the external electrodes is formed. The polarization treatment was performed by applying a voltage corresponding to . An alternating current of 1 kV/mm was applied to this polarized piezoelectric laminated element to drive it, and the following piezoelectric characteristics were measured based on the amount of displacement of the element.
　表１に示した各組成からなる圧電積層素子について、１ｋＶ／ｍｍ交流駆動による圧電定数ｄ３１、比誘電率εｒ、圧電効率ｄ３１／εｒ、及び、比誘電率の温度変化率εｒ－ＴＣを求めた。結果を表１に示す。
　測定にはいずれもＡｇｉｌｅｎｔ社製インピーダンスアナライザ４２９４Ａを用い、２０℃における圧電定数ｄ３１を共振－***振法によって求め、２０℃における比誘電率εｒを静電容量より計算して求めた。
　比誘電率の温度変化率εｒ－ＴＣは、同様の方法により恒温槽中にて静電容量を測定し、０℃以上８０℃以下での比誘電率を求め、０℃以上８０℃以下における比誘電率εｒの最大値を比誘電率εｒの最小値で除して求めた。 For the piezoelectric laminated element having each composition shown in Table 1, the piezoelectric constant d 31 , the dielectric constant ε r , the piezoelectric efficiency d 31 /ε r , and the temperature change rate ε r of the dielectric constant under 1 kV/mm AC drive. - Asked for TC. Table 1 shows the results.
Impedance analyzer 4294A manufactured by Agilent was used for all measurements, piezoelectric constant d 31 at 20° C. was determined by the resonance-antiresonance method, and dielectric constant ε r at 20° C. was calculated from capacitance.
The rate of change in relative permittivity with temperature ε r −TC is obtained by measuring the capacitance in a constant temperature bath by the same method, obtaining the relative permittivity at 0° C. or higher and 80° C. or lower. It was obtained by dividing the maximum value of relative permittivity εr by the minimum value of relative permittivity εr .
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　圧電効率についてはｄ３１／εｒ≧３．８（ｐＣ／Ｎ）、比誘電率の温度変化率についてはεｒ－ＴＣ≦３２０％である場合に、圧電特性が良好であると判断した。 Good piezoelectric characteristics were determined when d 31 /ε r ≧3.8 (pC/N) for the piezoelectric efficiency and ε r −TC ≦320% for the temperature change rate of the dielectric constant.
　ＢａＴｉＯ３に対して、Ｃａ置換率を０．５ｍｏｌ％以上１．７５ｍｏｌ％以下、Ｚｒ置換率を０．５ｍｏｌ％以上１．７５ｍｏｌ％以下とし、更にＭｎＣＯ３を０．１５重量部以上５重量部以下添加した試料（試料番号Ｎｏ．１～Ｎｏ．１１）を用いた圧電積層素子においては、高い圧電効率と小さい比誘電率の温度変化率を有していた。 With respect to BaTiO3 , the Ca substitution rate is 0.5 mol% or more and 1.75 mol% or less, the Zr substitution rate is 0.5 mol% or more and 1.75 mol% or less, and MnCO3 is 0.15 parts by weight or more and 5 parts by weight. The piezoelectric laminated elements using the samples (sample numbers No. 1 to No. 11) added below had a high piezoelectric efficiency and a small temperature change rate of the dielectric constant.
　ａ／ｂ比（１．００６）及びＭｎＣＯ３添加量（０．１５重量部）が同じである場合、Ｃａ、Ｚｒ置換率が等しい（試料番号Ｎｏ．１、Ｎｏ．２、Ｎｏ．６、Ｎｏ．８）と、圧電積層素子がより高い圧電効率ｄ３１／εｒを得ることができ、特に置換率がＣａ：１．０ｍｏｌ％、Ｚｒ：１．０ｍｏｌとなる試料番号Ｎｏ．１において、最も高い値を得ることができた。 When the a/b ratio (1.006) and the amount of MnCO3 added (0.15 parts by weight) are the same, the Ca and Zr substitution rates are equal (sample numbers No. 1, No. 2, No. 6, No. .8), the piezoelectric laminated element can obtain a higher piezoelectric efficiency d 31 / εr , and in particular, sample No. 1 with a replacement ratio of Ca: 1.0 mol % and Zr: 1.0 mol. 1, the highest value could be obtained.
　Ｃａ及びＺｒの置換率がともに１．００ｍｏｌ％でＭｎＣＯ３添加量（０．１５重量部）が同じである場合（試料番号Ｎｏ．１、Ｎｏ．９、Ｎｏ．１０）、ａ／ｂ比が小さいほど、圧電積層素子がより高い圧電効率ｄ３１／εｒを得ることができ、かつ、より小さい比誘電率の温度変化率εｒ－ＴＣを有していた。 When the Ca and Zr substitution ratios are both 1.00 mol% and the MnCO3 addition amount (0.15 parts by weight) is the same (sample numbers No. 1, No. 9, and No. 10), the a/b ratio is The smaller the piezoelectric laminate element, the higher the piezoelectric efficiency d 31 /ε r and the smaller the temperature change rate ε r −TC of the dielectric constant.
　また、Ｃａ及びＺｒの置換率がともに０ｍｏｌ％のとき（試料番号Ｎｏ．１２）は、圧電積層素子の圧電効率ｄ３１／εｒが低く、充分な圧電効率が得られなかった。 Moreover, when the Ca and Zr substitution ratios were both 0 mol % (Sample No. 12), the piezoelectric efficiency d 31 / εr of the piezoelectric laminated element was low, and sufficient piezoelectric efficiency was not obtained.
　ＢａＴｉＯ３に対して、Ｃａ及びＺｒの置換率が２ｍｏｌ％又は５ｍｏｌ％の試料（試料番号Ｎｏ．１３、Ｎｏ．１４）を用いた圧電積層素子においては、圧電定数ｄ３１の低下及び比誘電率εｒの増大が著しく、ｄ３１／εｒで示した圧電効率が大きく低下した。また０～８０℃における比誘電率の温度変化率εｒ－ＴＣが増加しており、高温域の使用時に駆動電流増加が認められた。 In the piezoelectric laminated elements using samples (sample numbers No. 13 and No. 14) in which the substitution ratio of Ca and Zr is 2 mol% or 5 mol% with respect to BaTiO3 , the decrease in the piezoelectric constant d31 and the relative permittivity The increase in ε r was remarkable, and the piezoelectric efficiency indicated by d 31 /ε r greatly decreased. In addition, the temperature change rate ε r -TC of the relative permittivity in the range of 0 to 80° C. increased, and an increase in the drive current was recognized during use in the high temperature range.
　ＭｎＣＯ３の添加量の増加に伴い、圧電定数ｄ３１及び比誘電率εｒが低下し、特にＭｎＣＯ３の添加量が１０重量部を超えると（試料番号Ｎｏ．１６、Ｎｏ．１７）、圧電定数ｄ３１の低下が許容できない値となった。また、ＭｎＣＯ３の添加量が０．００重量部の場合（試料番号Ｎｏ．１５）は、絶縁抵抗の低下により分極不良が生じた。 As the amount of MnCO3 added increases, the piezoelectric constant d31 and the dielectric constant εr decrease . A decrease in the constant d31 resulted in an unacceptable value. Further, when the amount of MnCO 3 added was 0.00 parts by weight (Sample No. 15), poor polarization occurred due to a decrease in insulation resistance.
　次に、試料番号Ｎｏ．１及びＮｏ．１３の試料を用いて、圧電体セラミック層の厚さを６０μｍ又は１００μｍとした圧電積層素子を上記と同様の方法により作製し、圧電定数ｄ３１、比誘電率εｒ及び圧電効率ｄ３１／εｒを求めた。結果を表２に示す。 Next, sample number no. 1 and no. Using the 13 samples, piezoelectric laminated elements with piezoelectric ceramic layers having a thickness of 60 μm or 100 μm were produced by the same method as described above, and the piezoelectric constant d 31 , relative permittivity ε r and piezoelectric efficiency d 31 /ε were obtained. We asked for r . Table 2 shows the results.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　Ｃａ及びＺｒの置換率が１．０ｍｏｌ％のＮｏ．１、Ｎｏ．１８及びＮｏ．１９の試料を用いた圧電積層素子は、よりＣａ及びＺｒ置換率の高いＮｏ．１３、Ｎｏ．２０及びＮｏ．２１の試料を用いた圧電積層素子の性能と比較すると、圧電体セラミック層の厚さの減少に伴う圧電定数ｄ３１及び圧電効率ｄ３１／εｒの低下が小さく、特に圧電体セラミック層の厚さが３０μｍである場合においてその差が顕著である。これより、試料番号Ｎｏ．１～Ｎｏ．１１の試料は、Ｎｉを主成分とする内部電極層を有する圧電体セラミック層の厚さが３０μｍ以下の圧電積層素子において適した組成であるといえる。 No. 1 with a substitution rate of Ca and Zr of 1.0 mol %. 1, No. 18 and no. The piezoelectric laminated element using the sample of No. 19 has a higher Ca and Zr substitution rate. 13, No. 20 and no. 21, the piezoelectric constant d31 and the piezoelectric efficiency d31 / εr decrease less as the thickness of the piezoelectric ceramic layer decreases. The difference is remarkable when the thickness is 30 μm. From this, sample number No. 1 to No. Sample No. 11 can be said to have a composition suitable for a piezoelectric laminated element having a piezoelectric ceramic layer having a thickness of 30 μm or less and having internal electrode layers containing Ni as a main component.
１　圧電セラミック素体
２ａ、２ｂ、２ｃ、２ｄ、２ｅ、２ｆ、２ｇ、２ｈ、２ｉ、２ｊ　圧電体セラミック層
３ａ、３ｂ、３ｃ、３ｄ、３ｅ、３ｆ、３ｇ、３ｈ、３ｉ　内部電極層
４ａ、４ｂ　外部電極
１０　圧電積層素子 1 piezoelectric ceramic bodies 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i, 2j piezoelectric ceramic layers 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i internal electrode layers 4a, 4b External electrode 10 Piezoelectric multilayer element

Claims (3)

  1. 　複数の圧電体セラミック層と、前記圧電体セラミック層間に設けられた内部電極層と、前記内部電極層に電気的に接続された外部電極とを備え、
    　前記圧電体セラミック層が、Ｂａ、Ｃａ、Ｔｉ及びＺｒを含む酸化物、並びにＭｎを含有する圧電材料で構成され、
    　前記Ｂａ及び前記Ｃａの和に対する前記Ｃａのモル比ｘが０．００５≦ｘ≦０．０１７５であり、
    　前記Ｔｉ及び前記Ｚｒの和に対する前記Ｚｒのモル比ｙが０．００５≦ｙ≦０．０１７５であり、
    　前記酸化物１００重量部に対する前記Ｍｎの含有量が、ＭｎＯ換算で０．１５重量部以上５．０重量部以下であり、
    　前記内部電極層がＮｉを主成分とする、ことを特徴とする圧電積層素子。     comprising a plurality of piezoelectric ceramic layers, internal electrode layers provided between the piezoelectric ceramic layers, and external electrodes electrically connected to the internal electrode layers,
    the piezoelectric ceramic layer is composed of an oxide containing Ba, Ca, Ti and Zr, and a piezoelectric material containing Mn;
    The molar ratio x of Ca to the sum of Ba and Ca is 0.005 ≤ x ≤ 0.0175,
    the molar ratio y of the Zr to the sum of the Ti and the Zr is 0.005 ≤ y ≤ 0.0175;
    The Mn content relative to 100 parts by weight of the oxide is 0.15 parts by weight or more and 5.0 parts by weight or less in terms of MnO,
    A piezoelectric laminated element, wherein the internal electrode layers contain Ni as a main component.
  2. 　前記圧電体セラミック層の１層あたりの平均厚さが３０μｍ以下である請求項１に記載の圧電積層素子。 The piezoelectric laminated element according to claim 1, wherein the average thickness of each piezoelectric ceramic layer is 30 µm or less.
  3. 　前記モル比ｘと前記モル比ｙとが同じ値である、請求項１又は２に記載の圧電積層素子。 The piezoelectric laminated element according to claim 1 or 2, wherein the molar ratio x and the molar ratio y are the same value.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0645182A (en) * 1992-03-27 1994-02-18 Tdk Corp Multilayer ceramic chip capacitor
JP2012206889A (en) * 2011-03-29 2012-10-25 Tdk Corp Dielectric ceramic composition, and ceramic electronic component
JP2014172799A (en) * 2013-03-11 2014-09-22 Ricoh Co Ltd Piezoelectric material, manufacturing method of piezoelectric material, piezoelectric actuator, manufacturing method of piezoelectric actuator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0645182A (en) * 1992-03-27 1994-02-18 Tdk Corp Multilayer ceramic chip capacitor
JP2012206889A (en) * 2011-03-29 2012-10-25 Tdk Corp Dielectric ceramic composition, and ceramic electronic component
JP2014172799A (en) * 2013-03-11 2014-09-22 Ricoh Co Ltd Piezoelectric material, manufacturing method of piezoelectric material, piezoelectric actuator, manufacturing method of piezoelectric actuator

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