JP4901165B2 - Multilayer piezoelectric body - Google Patents

Description

  The present invention relates to a laminated piezoelectric material, for example, a fuel injection injector, an inkjet printer, or a piezoelectric sensor such as a piezoelectric resonator, an oscillator, an ultrasonic motor, an ultrasonic vibrator, a filter or acceleration sensor, a knocking sensor, and an AE sensor. In particular, the present invention relates to a laminated piezoelectric material suitably used as a print head using spreading vibration, stretching vibration, and thickness vibration.

  Conventionally, products using a piezoelectric ceramic include, for example, an actuator, a filter, a piezoelectric resonator (hereinafter, a concept including an oscillator), an ultrasonic vibrator, an ultrasonic motor, a piezoelectric sensor, and the like.

  Among these, for example, actuators have a very high response speed to electrical signals on the order of μsec, so they are applied to XY stage positioning actuators in semiconductor manufacturing equipment, actuators used in inkjet printer print heads, and the like. Yes. In particular, due to the recent increase in speed and cost of color printers, there is an increasing demand for use in ink ejection actuators such as inkjet printers.

  Such an actuator uses a piezoelectric displacement element. For example, a film type comprising a ceramic substrate acting as a vibration plate and a first electrode film, a piezoelectric film, and a second electrode film provided thereon. There has been proposed one composed of a piezoelectric actuating part (see, for example, Patent Document 1).

The ceramic substrate used as the diaphragm of such an actuator is made of zirconium oxide, aluminum oxide, magnesium oxide, aluminum nitride, silicon nitride or the like. A piezoelectric displacement element is placed on such a ceramic substrate at 100 ° C. When bonding using an adhesive that cures at a high temperature as described above, the linear displacement coefficient of the ceramic substrate and that of the piezoelectric displacement element are different, so that compressive stress is generated in the piezoelectric displacement element. There has been a problem that the piezoelectric characteristics of the piezoelectric displacement element are significantly deteriorated by the compressive stress. In order to solve this, it has been proposed that a ceramic substrate used as a diaphragm is made of piezoelectric ceramics having the same composition (see, for example, Patent Document 2).
W02002 / 073710 JP 2004-165650 A

  However, when the piezoelectric ceramics described in Patent Document 1 and Patent Document 2 are used as actuators, there is a problem in that the displacement characteristics of a plurality of piezoelectric displacement elements provided on the same plane vary. For example, in a piezoelectric actuator in which a plurality of piezoelectric displacement elements are formed on a diaphragm, the amount of displacement varies between the plurality of piezoelectric displacement elements.

  Further, when the driving of the piezoelectric displacement element is continued by repeatedly applying and removing the electric field between the individual surface electrode and the common electrode layer of the piezoelectric displacement element, the displacement amount of a certain element among the plurality of piezoelectric displacement elements changes. However, there is a problem that the degree of deterioration of driving characteristics varies such that the amount of displacement of another element is greatly reduced.

  Accordingly, an object of the present invention is to provide a laminated piezoelectric body that suppresses variation in displacement amount and variation in driving characteristics of a plurality of displacement regions or a plurality of displacement elements provided on the surface.

  The multilayer piezoelectric body of the present invention includes a plurality of surface electrodes on a surface of a multilayer body in which a piezoelectric ceramic layer and an internal electrode layer are stacked, and a displacement region corresponding to each of the surface electrodes and the displacement region on the surface of the multilayer body. The piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer have an average crystal grain size of 1.2 to 1.8 μm and 80 of the piezoelectric ceramic crystal particles. % Or more has a crystal grain size within a range of ± 15% of the average crystal grain size.

  In another laminated piezoelectric material of the present invention, a common electrode layer and a piezoelectric ceramic layer are formed in this order on a diaphragm made of piezoelectric ceramic, and a plurality of individual surface electrodes are formed on the surface of the piezoelectric ceramic layer. A plurality of piezoelectric displacement elements formed by the individual surface electrode, the common electrode layer facing the individual surface electrode, and the piezoelectric ceramic layer sandwiched between the individual surface electrodes, are formed on the diaphragm. The piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer have an average crystal grain size of 1.2 to 1.8 μm, and 80% or more of the piezoelectric ceramic crystal particles are within a range of ± 15% of the average crystal grain size. It is characterized by having a crystal grain size of

  It is preferable that at least one of the internal electrode layer and the common electrode layer is made of a silver-palladium alloy containing silver in a proportion of 80% by volume or more.

  When the grain size of the piezoelectric ceramic crystal particles is increased, the domain rotational strain increases and a large displacement is obtained, but the piezoelectric constant varies, but the average crystal grain size of the piezoelectric ceramic crystal grains constituting the piezoelectric ceramic layer is 1. 2 to 1.8 μm, and 80% or more of the piezoelectric ceramic crystal particles are set within a range of ± 15% of the average crystal grain size, whereby a displacement region or a displacement element provided in the same plane It is possible to obtain a laminated piezoelectric body that suppresses deterioration variation in piezoelectric characteristics and driving characteristics thereof.

  The multilayer piezoelectric body of the present invention includes a plurality of surface electrodes on a surface of a multilayer body in which a piezoelectric ceramic layer and an internal electrode layer are stacked, and a displacement region corresponding to each of the surface electrodes and the displacement region on the surface of the multilayer body. The piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer have an average crystal grain size of 1.2 to 1.8 μm and 80 of the piezoelectric ceramic crystal particles. % Or more has a crystal grain size within a range of ± 15% of the average crystal grain size.

  FIG. 1 is a cross-sectional view showing an embodiment of the laminated piezoelectric material of the present invention. Hereinafter, the present invention will be described using a laminated piezoelectric material having the structure of FIG. 1 as an example.

  According to FIG. 1, the laminated piezoelectric body 1 has an internal electrode layer 4 and a piezoelectric ceramic layer 5 formed in this order on a diaphragm 3, and a plurality of surface electrodes 6 are formed on the surface of the piezoelectric ceramic layer 5. The displacement element 7 is configured by the facing portion of the internal electrode layer 4 facing the surface electrode 6, the surface electrode 6, and the piezoelectric ceramic layer 5 existing in a region sandwiched between these electrodes 4 and 6.

  In this way, a plurality of displacement elements 7 are formed on the surface of the vibration plate 3, and the vibration portion 8 is formed by the displacement element 7 and a portion of the vibration plate 3 that contacts the displacement element 7. Since the displacement element 7 is displaced by applying a voltage between the internal electrode layer 4 and the internal electrode layer 4, the vibration part in contact with the displacement element 7 is also displaced accordingly, and as a result, the entire vibration part 8 is displaced.

  Needless to say, the plurality of vibrating portions 8 are provided with electric wiring so that a voltage can be applied to the internal electrode layer 4 and the surface electrode 6 from an external drive circuit.

  According to the present invention, the average crystal grain size of the piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer 5 is in the range of 1.2 to 1.8 μm, and 80 of the piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer 5. It is important that the composition has a crystal grain size in the range of ± 15% of the average crystal grain size.

  For example, if the average crystal grain size of the piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer 5 is 1.5 μm, the value of “−15%” of the average crystal grain size of 1.5 μm is 1.275 μm and “+15 Since the value of “%” is 1.725 μm, it is necessary that 80% or more of the piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer 5 fall within the range of 1.275 to 1.725 μm.

  In this way, by controlling the average crystal grain size and grain size distribution within the above ranges, it is possible to reduce the variation in domain rotational strain for each piezoelectric element, and to improve the piezoelectric characteristics in the plane of the laminated piezoelectric body and its driving characteristics. It is possible to realize a laminated piezoelectric body that suppresses deterioration variation.

  The displacement characteristics of piezoelectric ceramics increase as crystal grains increase. However, as crystal grains increase, the variation in domain rotational strain increases. Therefore, by setting the average crystal grain size within the above range, the variation in piezoelectric constant can be reduced. Can be reduced. In particular, the average crystal grain size is preferably 1.3 to 1.7 μm and 1.4 to 1.6 μm from the viewpoint of further reducing the variation.

  In a piezoelectric actuator using a substrate made of piezoelectric ceramics as a vibration plate or a piezoelectric actuator having a constrained region around a displacement element, stress is applied from the non-displacement region, which is a constrained region around the vibration plate or element. By being applied, the orientation state of the crystal changes. As a result, the displacement is greatly deteriorated due to the change of the restraint state of the displacement region or the piezoelectric displacement element, but the crystal orientation can be hardly changed by setting the particle size distribution in the above range. Variations in drive deterioration can be reduced.

  In particular, in order to suppress in-plane drive deterioration variation, the number of crystal grains distributed in a range of ± 15% of the average crystal grain size is 85% or more, further 90% or more, more preferably 95% of the total number of grains. % Or more is preferable.

  The average crystal grain size can be measured using the intercept method by observation with an electron microscope or an optical microscope.

  The piezoelectric ceramic layer 5 is made of piezoelectric ceramic. The piezoelectric ceramic in the present invention means a ceramic exhibiting piezoelectricity, and includes a Bi layer compound, a tungsten bronze structure material, a perovskite structure compound of Nb acid alkali compound, Pb. Perovskite structure compounds containing lead zirconate titanate (PZT), lead titanate, etc. can be exemplified, but among these, lead zirconate titanate and lead titanate containing Pb have wettability with Ag-containing electrodes. It is preferable at the point which raises and raises the adhesive strength with an Ag containing electrode.

  In particular, lead titanate and barium titanate can obtain a large displacement, and in particular, a lead zirconate titanate-based compound provides a stable piezoelectric sintered body having a higher d constant. This is preferable.

The piezoelectric ceramic layer 5 preferably contains at least one of Sr, Ba, Ni, Sb, Nb, Zn, Yb and Te. As a result, a more stable piezoelectric sintered body can be obtained. For example, Pb (Zn _1/3 Sb _2/3 ) O ₃ and Pb (Ni _1/2 Te _1/2 ) O ₃ are solidified as subcomponents. What melt | dissolves can be illustrated.

  In particular, it is desirable to further contain an alkaline earth element as the A site constituent element. As the alkaline earth element, Ba and Sr are particularly preferable in that a high displacement can be obtained, and the inclusion of 0.02 to 0.08 mol of Ba and 0.02 to 0.12 mol of Sr is particularly mainly tetragonal composition. It is advantageous to obtain a large displacement in the case of the following composition.

For _{example, Pb 1-x-y Sr} x Ba y (Zn 1/3 Sb 2/3) a (Ni 1/2 Te 1/2) b Zr 1-a-b-c Ti c O 3 + αwt% Pb 1 _{/ 2} NbO ₃ (0 ≦ x ≦ 0.14, 0 ≦ y ≦ 0.14, 0.05 ≦ a ≦ 0.1, 0.002 ≦ b ≦ 0.01, 0.44 ≦ c ≦ 0.50 , Α = 0.1 to 1.0).

  Further, according to the present invention, the internal electrode layer 4 produced by co-firing with the piezoelectric ceramic layer 5 has a silver content of 80% or more, particularly 85% by volume or more, more preferably 90% by volume or more, and more preferably 93% by volume or more. It is made of a silver-palladium alloy containing, and thereby, an effect of reducing compressive stress due to contraction of the electrode can be expected.

  Furthermore, it is preferable to control the magnitude of residual stress generated in the laminated piezoelectric body after firing to 100 MPa or less. As a means for reducing the residual stress, a method of reducing the thickness of the internal electrode and a method of containing a ceramic filler in the internal electrode can be used.

Moreover, in order to suppress aggregation of the internal electrode layer 4, the average particle diameter of the internal electrode layer is preferably 0.1 to 5.0 μm, particularly preferably 0.5 to 3 μm, more preferably 1 to 2 μm, and further the adhesion strength. enhanced, in order to further stabilize piezoelectric properties d ₃₁ to reduce the residual stress, at least some of the electrodes, in particular the internal electrode layer 2 preferably comprises a piezoelectric ceramic.

  This piezoelectric ceramic is contained in a proportion of 10 to 60% by volume, particularly 18 to 50% by volume, and more preferably 20 to 30% by volume when the total amount of the silver-palladium alloy is 100% by volume. This is preferable for reducing the residual stress while increasing the adhesion strength between the electrodes. Furthermore, it is preferable for the piezoelectric ceramics present in the internal electrode layer 4 to have substantially the same composition as the piezoelectric ceramic layer 5 in order to further improve the adhesion and more stable driving.

  Next, the manufacturing method of the laminated piezoelectric material of the present invention will be described in the case where lead zirconate titanate (hereinafter referred to as PZT) is used as the piezoelectric ceramic.

  First, PZT powder having a purity of 99% or more and an average particle diameter of 1.2 μm or less is prepared as a piezoelectric ceramic powder as a raw material. In order to control the average particle size of the piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer after firing to 1.2 to 1.8 μm, the average particle size is 1.2 μm or less, particularly 1 μm or less, further 0.8 μm or less. It is preferable to use this raw material powder.

  Further, it is preferable that the particle size variation of the raw material powder is small. In particular, the maximum particle size is preferably 2 μm or less, particularly 1.8 μm or less, and more preferably 1.6 μm or less, and the particle size variation is preferably within ± 20% of the average particle size. If it is within ± 20%, small particles disappear during firing, and it is possible to make the average crystal grain size within ± 15%. For this purpose, it is necessary to precisely control the firing conditions. In order to control the particle size distribution more easily, it is preferable to set the particle size variation of the raw material powder within ± 15%, particularly within ± 10%.

  An appropriate organic binder is added to the piezoelectric ceramic powder and formed into a tape shape. An Ag-Pd paste is applied and laminated as a part of the produced green sheet as an internal electrode layer, and further at a pressure of 10 to 50 MPa. After pressing to produce a laminate, it is cut into a desired shape.

It is preferable raw density before sintering of a green sheet is 4.5 g / cm ² or more, by increasing the sintered density 4.5 g / cm ² or more, and more can be fired at a low temperature If the green density is further increased, it is possible to suppress the evaporation of Pb.

  The obtained green sheet is debindered at about 400 ° C. and then fired.

  The firing conditions vary depending on the particle size of the raw material powder, but are set so that the average particle size of the piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer is 1.2 to 1.8 μm. For example, when a PZT powder having an average particle size of 1.6 μm is used, the firing temperature is 800 to 1100 ° C., particularly 850 to 1050 ° C., further 870 to 970 ° C., and the firing time is 0.5 to 3 hours, particularly 1 It may be set to ~ 2.5 hours.

  Moreover, when employ | adopting the raw material containing a highly volatile element like Pb, it is preferable to use the baking atmosphere with a high Pb partial pressure, or to bake in an airtight container.

  Furthermore, by using oxygen as the firing atmosphere gas and increasing the oxygen concentration, grain growth of the crystal grain size can be suppressed.

  The laminated piezoelectric material of the present invention can be completed by polarizing the plurality of electrodes formed on the surface by firing in this way.

  Even when a piezoelectric ceramic other than PZT is used, the present invention can be carried out in the same manner as in the case of PZT.

The laminated piezoelectric material of the present invention suppresses variations in deterioration of piezoelectric characteristics and driving characteristics in the surface, so that it is a liquid ejecting injector, an ink jet printer, or a piezoelectric resonator, an oscillator, an ultrasonic motor, and an ultrasonic vibrator. It can be used for filters, acceleration sensors, knocking sensors, piezoelectric sensors such as AE sensors, and the like. In addition, since the response speed with respect to electrical signals is as high as 10 ⁻⁶ seconds, it is applied to a piezoelectric actuator for positioning an XY stage of a semiconductor manufacturing apparatus, a piezoelectric actuator used for a print head of an ink jet printer, or the like.

  In particular, when a piezoelectric actuator that uses spreading vibration, elongation vibration, and thickness vibration is employed in a print head, high-definition printing with little color unevenness can be realized with small variations in ink ejection characteristics between nozzles. For example, the laminated piezoelectric material of the present invention can be used as the print head shown in FIG.

  According to FIG. 2A, the piezoelectric actuator 1 has a structure provided on the flow path member 13. In the flow path member 13, a plurality of liquid pressurizing chambers 13 a are partitioned by partition walls 13 b, and the liquid pressurizing chambers 13 a are arranged side by side so as to contact the piezoelectric actuator 1.

  In the piezoelectric actuator 1, the common electrode 4 and the piezoelectric ceramic layer 5 are formed in this order on the diaphragm 3, and a plurality of surface electrodes 6 are provided on the surface of the piezoelectric ceramic layer 5. As shown in FIG. 2B, a plurality of the surface electrodes 6 are arranged on the surface of the piezoelectric ceramic layer 5 so that the surface electrode 6 and the common electrode 4 in a region facing the surface electrode 6 are sandwiched between them. A plurality of piezoelectric displacement portions 7 composed of the piezoelectric ceramic layer 5 thus formed are formed.

  The piezoelectric actuator 1 is disposed on the flow path member 13 so that the surface electrode 6 is positioned immediately above the liquid pressurizing chamber 13a.

  Such a print head applies a voltage between the common electrode 4 and the predetermined surface electrode 6 to displace the piezoelectric ceramic layer 5 immediately below the surface electrode 6, thereby causing the piezoelectric displacement portion 7 and the diaphragm to be in contact therewith. The displacement region constituted by the above is deformed so as to change the volume of the liquid pressurizing chamber 13 a, pressurizes the ink in the liquid pressurizing chamber 13 a, and the ink is ejected from the ink discharge port 18 opened at the bottom of the flow path member 13. Drops can be ejected.

  By using such a print head, high-definition printing with little color unevenness can be easily realized.

  The laminated piezoelectric material of the present invention was produced and applied to the ink jet print head shown in FIG. 3 as a piezoelectric actuator.

First, a piezoelectric ceramic powder containing lead zirconate titanate whose purity was 99.5% and whose average particle size and particle size distribution are shown in Table 1 was prepared. Its composition is Pb _0.8 Sr _0.1 Ba _0.1 (Zn _1/3 Sb _2/3 ) _0.08 (Ni _1/2 Te _1/2 ) _0.07 Zr _0.4 Ti _0.45 O ₃ was 99.5% by mass and Pb _1/2 NbO ₃ was 0.5% by mass.

  The average particle size of the raw material powder was determined from the intensity of scattered light and the scattering angle by a laser diffraction scattering method. Further, the variation in particle size was evaluated according to ±% of the average particle size. A numerical value of 20 in the table indicates that it is within ± 20%.

  The average particle diameter of the electrode was measured in the same manner.

  The green sheet is prepared by adding butyl methacrylate as a water-based binder, ammonium polycarboxylate as a dispersant, and isopropyl alcohol and pure water as a solvent to the piezoelectric ceramic powder, and mixing the slurry with a carrier film by a doctor blade method. A sheet having a thickness of 30 μm was prepared.

  The green density of the green sheets was measured by measuring the dimensions and calculating the volume from the dimensions, and by measuring the weight and measuring the green density.

  The obtained green sheet was cut into a rectangular shape, and an internal electrode layer paste was printed on a part of the green sheet at a thickness of 4 μm on the surface of the green sheet for the vibration plate to form an internal electrode layer. As the internal electrode layer paste, the raw material powder showing the material, average particle diameter and Ag content shown in Table 1 was used.

  Furthermore, a green sheet for a piezoelectric ceramic layer was laminated on the diaphragm green sheet with the surface on which the internal electrode layer was printed facing upward, and pressed to obtain a laminated molded body.

  After degreasing the laminated molded body at 400 ° C. for 10 hours, the laminated molded body was fired under the firing conditions shown in Table 1 in a firing furnace having a temperature control accuracy of ± 2%, and the piezoelectric ceramic layer and the diaphragm And a laminated piezoelectric body made of internal electrode layers.

  The oxygen concentration was converted from the gas flow ratio with nitrogen gas.

  The lattice constant ratio c / a, residual stress, porosity, and crystal grain size of the piezoelectric ceramic layer provided on the surface of the obtained laminated piezoelectric material were measured.

  For the measurement of the lattice constant ratio c / a, the lattice constant was calculated from the diffraction peak by X-ray diffraction, and c / a was calculated by dividing the c-axis lattice constant by the a-axis lattice constant.

  The porosity was measured by Archimedes method.

  The silver content was quantitatively analyzed by fluorescent X-ray analysis using a calibration curve prepared in advance.

  The crystal grain size of the piezoelectric ceramic layer was photographed at 10 locations within the substrate surface with an optical microscope of 2000 times, and the crystal size of 10 particles was measured by the intercept method at each location. The crystal grain size of the crystal particles was measured. And the minimum value, the maximum value, and the average value were calculated.

  Next, a total of 100 surface electrodes 3 were formed on one side of the laminate body, 10 rows each in length and width. The surface electrode was formed by applying Au paste by screen printing and baking it in an air atmosphere at 700 ° C. for 30 minutes. The thickness of the obtained multilayer piezoelectric body including the surface electrode was about 50 μm.

  Finally, the displacement measuring print head shown in FIG. 3 was produced. That is, external wiring is connected to each of the surface electrodes 6 so that a voltage can be supplied to each surface electrode 6 independently. Further, the flow path member 13 was attached to the laminated piezoelectric body on the vibration plate 3 side so that each surface electrode 6 and the liquid pressurizing chamber 13a were arranged at corresponding positions.

  All displacement elements 7 were polarized by applying a DC voltage of 3 kV / mm for 5 minutes in the thickness direction between the internal electrode layer and the surface electrode of the obtained print head. Thereafter, the displacement element is driven with a rectangular wave of 2 kHz and an electric field strength of 1 kV / mm, and the amount of displacement at that time is measured as an initial value from the opening 28 with a laser Doppler displacement meter. The displacement was evaluated. Next, the durability test was performed by driving continuously for 100 hours, and the displacement was measured again after the test was completed, and the deterioration rate of the displacement after the durability with respect to the initial value was obtained. The deterioration rate is defined as (Yb−Ya) / Ya, where Ya is the initial value and Yb is the value after endurance. In addition, the variation was the largest with respect to the average value, and the difference between the average value and the average value was displayed as a percentage of the average value.

The results are shown in Table 1.

  Sample No. of the present invention. As for 2-7, 9-11, and 13-24, the displacement initial value was 70 nm or more, the dispersion | variation was less than 10%, the average value of deterioration rate was less than 5%, and the distribution of deterioration rate was less than 5%.

  On the other hand, the sample No. 1 outside the scope of the present invention has a crystal grain size of 1 μm as the crystal grain size of the piezoelectric ceramic layer. 1 had an initial displacement of less than 70 nm.

  In addition, the sample No. 2 outside the scope of the present invention has a crystal grain size of 2 μm as the crystal grain size of the piezoelectric ceramic layer. No. 8 had an average deterioration rate greater than 5%.

  In addition, the sample no. No. 8 had a deterioration rate distribution larger than 5%.

It is a schematic sectional drawing which shows the structure of the laminated piezoelectric material of this invention. The structure of the print head which used the laminated piezoelectric material of this invention as a piezoelectric actuator is shown, (a) is a schematic sectional drawing, (b) is a top view. The laminated piezoelectric material of the present invention used in the examples shows a structure in which the laminated piezoelectric material is joined to the measurement flow path member, where (a) is a schematic sectional view and (b) is a plan view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laminated piezoelectric body 2 ... Displacement element 3 ... Diaphragm 4 ... Internal electrode layer 5 ... Piezoceramic layer 6 ... Surface electrode 7 ... Displacement element 8 ... Displacement Part 13: Channel member 13a ... Liquid pressurizing chamber 13b ... Partition 18 ... Ink ejection port

Claims (3)

A plurality of surface electrodes are provided on the surface of a laminate in which a piezoelectric ceramic layer and an internal electrode layer are laminated, and a displacement region corresponding to each of the surface electrodes is formed on the surface of the laminate and a non-layer formed so as to surround the displacement region. An average crystal grain size of the piezoelectric ceramic crystal grains constituting the piezoelectric ceramic layer is 1.2 to 1.8 μm, and 80% or more of the piezoelectric ceramic crystal grains are the average crystal grain size A laminated piezoelectric material having a crystal grain size within a range of ± 15% of the above. A common electrode layer and a piezoelectric ceramic layer are formed in this order on a diaphragm made of piezoelectric ceramic, and a plurality of individual surface electrodes are formed on the surface of the piezoelectric ceramic layer. The individual surface electrode and the individual surface electrode A plurality of piezoelectric displacement elements formed by opposing common electrode layers and the piezoelectric ceramic layer sandwiched between them are formed on the diaphragm, and the piezoelectric ceramic crystal particles constituting the piezoelectric ceramic layer are formed. An average crystal grain size is 1.2 to 1.8 μm, and 80% or more of the piezoelectric ceramic crystal particles have a crystal grain size within ± 15% of the average crystal grain size. 3. The multilayer piezoelectric body according to claim 1, wherein at least one of the internal electrode layer and the common electrode layer is made of a silver-palladium alloy containing silver in a proportion of 80% by volume or more.

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