JP2011009269A - Piezoelectric material, laminated piezoelectric element and method of manufacturing the same, and unit junction laminated piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric material excellent in displacement performance, a laminated piezoelectric element and a method of manufacturing the same, and a unit junction laminated piezoelectric element.SOLUTION: The piezoelectric material is expressed by a general a formula (1): (PbSr){ZrTi(YNbSb)}O. The general formula (1) satisfies relations of 0.90≤a+b≤0.98, 0.03≤b≤0.08, c+d+e+f+g=1, 0.980≤c+d≤0.998, 0.45≤d≤0.48, 0.001≤e+f≤0.01, and 0.001≤g≤0.009. Also provided are: the laminated piezoelectric element 2 including a piezoelectric body layer 21 made of the piezoelectric material, a ceramic laminate 20 constituted by alternately laminating a plurality of electrode disposition layers 22, 23, and a pair of side electrodes 28, 29 formed on the side surfaces thereof; and a method of manufacturing the same. The unit junction laminated piezoelectric element 1 is constituted by joining a plurality of the laminated piezoelectric elements 2 in a laminating direction.

Description

  The present invention relates to a piezoelectric material that can be expanded and contracted by applying a voltage, a laminated piezoelectric element using the piezoelectric material as a piezoelectric layer, a method for manufacturing the same, and a unit bonded laminated piezoelectric element obtained by further laminating the laminated piezoelectric element. About.

An actuator using a piezoelectric element is used for a drive source of a fuel injection valve and various electrical components.
In general, a perovskite type compound such as a PZT (lead zirconate titanate) material represented by ABO ₃ has been used as a piezoelectric material used for a piezoelectric element. As the piezoelectric material, a material having a large displacement is desired, and various piezoelectric materials made of complex oxides having a specific composition have been developed so far.

In order to obtain a piezoelectric material with a large displacement, it is considered important to increase the mobility of the domain wall of the PZT crystal.
The mobility of the domain wall depends on the amount of defects at the A site where Pb is arranged. For example, when the B site of PZT is replaced with an element having a large valence, defects are generated at the A site due to charge compensation, and the amount of displacement is reduced. Can be increased. As an example, a composition in which a part of Pb is replaced with La and MnO ₂ is reduced to 1.0% by weight or less to improve piezoelectric characteristics has been developed (see Patent Document 1).

Japanese Patent Publication No. 8-728

  However, the displacement performance of the conventional piezoelectric material has not been sufficient depending on the application of the actuator. In particular, in applications such as a drive source for a fuel injection valve of an internal combustion engine, higher displacement performance has been required. In addition, the piezoelectric material containing Mn has a problem that by-products are generated, the change in piezoelectric characteristics with time increases, and stable piezoelectric characteristics cannot be exhibited. Therefore, in the piezoelectric material containing Mn, it is necessary to take further measures for stabilizing the characteristics.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a piezoelectric material excellent in displacement performance, a laminated piezoelectric element, a manufacturing method thereof, and a unit bonded laminated piezoelectric element.

The first invention is a piezoelectric material represented by the general formula (1): (Pb _a Sr _b ) {Zr _c Ti _d (Y _e Nb _f Sb _g )} O ₃ ,
0.90 ≦ a + b ≦ 0.98,
0.03 ≦ b ≦ 0.08,
c + d + e + f + g = 1,
0.980 ≦ c + d ≦ 0.998,
0.45 ≦ d ≦ 0.48,
0.001 ≦ e + f ≦ 0.01, and 0.001 ≦ g ≦ 0.009
The piezoelectric material is characterized by satisfying the following relationship (claim 1).

According to a second aspect of the present invention, there is provided a ceramic laminate formed by alternately laminating a plurality of piezoelectric layers made of a piezoelectric material that can be expanded and contracted by applying a voltage, and electrode arrangement layers including electrode portions constituting internal electrodes, and In the multilayer piezoelectric element having a pair of side electrodes formed on the side surface of the ceramic laminate,
The piezoelectric layer is a multilayer piezoelectric element comprising the piezoelectric material of the first invention as a main component (claim 2).

According to a third aspect of the present invention, there is provided a ceramic laminate formed by alternately laminating piezoelectric layers made of a piezoelectric material that can be expanded and contracted by applying a voltage, and electrode arrangement layers including electrode portions constituting internal electrodes, and In the manufacturing method of the multilayer piezoelectric element having a pair of side electrodes formed on the side surface of the ceramic laminate,
The Pb source, Sr source, Zr source, Ti source, Y source, Nb source, and Sb source are _expressed by the general formula (1): (Pb _a Sr _b ) (Zr _c Ti _d (Y _e Nb _f Sb _g )) O ₃ (provided that 0.90 ≦ a + b ≦ 0.98, 0.03 ≦ b ≦ 0.08, c + d + e + f + g = 1, 0.980 ≦ c + d ≦ 0.998, 0.45 ≦ d ≦ 0.48,. 001 ≦ e + f ≦ 0.01 and 0.001 ≦ g ≦ 0.009) are mixed at a mixing ratio to prepare a raw material mixture,
A calcining step of calcining the raw material mixture at a temperature of 1000 ° C. or less to obtain calcined powder;
A sheet molding step of obtaining a molded body sheet by adding at least a binder to the calcined powder and mixing to form a sheet; and
An electrode printing step of obtaining an electrode printing sheet by printing an electrode material containing a conductive metal on the molded body sheet,
A laminating step of laminating a plurality of the electrode print sheets to produce a laminate;
A degreasing step for degreasing the laminate,
A firing step of firing the laminate after the degreasing step to obtain the ceramic laminate;
A method of manufacturing a multilayer piezoelectric element, comprising: a step of forming a side electrode on the ceramic laminate, wherein the side electrode is formed.

  According to a fourth aspect of the present invention, there is provided a unit bonded multilayer piezoelectric element configured by bonding a plurality of the multilayer piezoelectric elements obtained by the multilayer piezoelectric element of the second invention or the manufacturing method of the third invention in the stacking direction. It is in.

In the first invention, the piezoelectric material is made of a PZT material represented by a general formula ABO ₃ and has a specific composition represented by the general formula (1).
Therefore, the piezoelectric material can exhibit excellent displacement performance. Further, the piezoelectric material does not contain Mn which generates a by-product and lowers the stability of the piezoelectric characteristics. Therefore, the piezoelectric material can stably exhibit the piezoelectric characteristics such as the above-described excellent displacement performance for a long period of time.

In the general formula (1), 0.03 ≦ b ≦ 0.08. That is, by adding Sr, defects are generated in the Pb crystal at the A site, the mobility of the domain wall is increased, and the displacement performance can be improved.
When b <0.03, the Curie temperature of the piezoelectric material may be lowered to, for example, 300 ° C. or lower. As a result, it may be difficult to apply the piezoelectric material in a high temperature environment such as an internal combustion engine of an automobile. On the other hand, when b> 0.08, the displacement performance may be reduced. Preferably, b is 0.03 or more and 0.07 or less.

In the general formula (1), 0.90 ≦ a + b ≦ 0.98 and c + d + e + f + g = 1. That is, in the general formula (1), the blending ratio of the A site to the B site is reduced. Therefore, Pb defects in the compound represented by the general formula (1) can be increased. As a result, the mobility of the domain wall is increased and the displacement performance can be improved.
In the case of a + b <0.90, there is a possibility that firing at a high temperature of 1100 ° C. or higher is necessary when the piezoelectric material is manufactured. And it becomes easy to produce | generate a by-product at the time of baking at high temperature, and there exists a possibility that the improvement effect of displacement performance may not fully be acquired by this by-product. On the other hand, when a + b> 0.98, the amount of defects becomes small, and there is a possibility that the effect of improving the displacement performance cannot be obtained sufficiently. Preferably, a + b is 0.93 or more and 0.96 or less.

In the general formula (1), 0.980 ≦ c + d ≦ 0.998, 0.45 ≦ d ≦ 0.48, 0.001 ≦ e + f ≦ 0.01, and 0.001 ≦ g ≦ 0. 009.
That is, Nb and Y are added to the B site, and Sb is further added. Therefore, defects can be generated at the A site by charge compensation.
In particular, Sb (ion radius: 61 pm) having an ionic radius that easily replaces Ti (ion radius: 60.5 pm) has a higher electron withdrawing ability than Nb (Nb electronegativity: 1.6, Sb electricity) Negative degree: 2.0 (polling)), which has an effect of relaxing the crystal lattice. Therefore, the displacement performance can be improved.

In the case of e + f <0.001, the amount of defects becomes small, and there is a possibility that the effect of improving the displacement performance can hardly be obtained. On the other hand, when e + f> 0.01, there is a possibility that the picropore phase remains and the displacement performance deteriorates. Preferably, e + f is 0.003 or more and 0.008 or less.
In addition, when g <0.001, the amount of defects becomes small, and there is a possibility that the effect of improving the displacement performance can hardly be obtained. On the other hand, when g> 0.009, a heterogeneous phase remains, and the displacement performance may be deteriorated. Preferably, g is 0.002 or more and 0.008 or less.

In the case of c + d <0.980, a heterogeneous phase remains and the displacement performance may be deteriorated. On the other hand, when c + d> 0.998, the amount of defects becomes small, and there is a possibility that the effect of improving the displacement performance can hardly be obtained.
In addition, when d <0.45, a different phase remains, and the displacement performance may be deteriorated. On the other hand, in the case of d> 0.48, the amount of defects becomes small, and there is a possibility that the effect of improving the displacement performance is hardly obtained.

  Thus, according to the first aspect, a piezoelectric material having excellent displacement performance can be provided.

Next, in the second and third inventions, the multilayer piezoelectric element having a piezoelectric layer made of the piezoelectric material of the first invention can be obtained.
Therefore, taking advantage of the excellent characteristics of the piezoelectric material of the first invention, the multilayer piezoelectric element can exhibit excellent displacement performance.

  The unit-bonded laminated piezoelectric element of the fourth invention is obtained by further laminating the laminated piezoelectric element of the second invention and the laminated piezoelectric element obtained by the manufacturing method of the third invention. Therefore, the unit bonded multilayer piezoelectric element can exhibit excellent displacement performance by utilizing the superior displacement performance of the multilayer piezoelectric element.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the structure of the unit joining laminated piezoelectric element concerning Example 1. FIG. FIG. 3 is an explanatory diagram illustrating a structure of a multilayer piezoelectric element according to the first embodiment. FIG. 3 is an explanatory diagram illustrating a cross-sectional structure of the multilayer piezoelectric element according to the first embodiment. Explanatory drawing which shows the process of forming the 1st electrode printing sheet concerning Example 1. FIG. Explanatory drawing which shows the process of forming the 2nd electrode printing sheet concerning Example 1. FIG. Explanatory drawing which shows the process of forming the loss | disappearance material printing sheet concerning Example 1. FIG. Explanatory drawing which shows the process of laminating | stacking the electrode printing sheet and the loss | disappearance material printing sheet concerning Example 1. FIG. FIG. 2 is a top view of a pre-laminated body according to Example 1. Explanatory drawing which shows the cross section (AA cross section of FIG. 8) of the preliminary laminated body concerning Example 1. FIG. FIG. 3 is an explanatory view showing a cross-sectional structure of an intermediate laminate according to Example 1. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the process concerning Example 1 which joins the several lamination type piezoelectric element, and produces a unit joining laminated type piezoelectric element. BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 3 is an explanatory diagram illustrating a relationship between an Sr amount and a displacement amount according to the first embodiment. Explanatory drawing which shows the relationship between the total amount of Pb and Sr and displacement amount concerning Example 1. FIG. Explanatory drawing which shows the relationship between Sb amount and displacement amount concerning Example 1. FIG. Explanatory drawing which shows the relationship between the total amount of Y and Nb concerning Example 1, and a displacement amount.

Next, a preferred embodiment of the present invention will be described.
In the present invention, the multilayer piezoelectric element includes the ceramic laminate and a pair of side electrodes formed on a side surface (a surface in a direction perpendicular to the lamination direction) of the ceramic laminate.
The ceramic laminate is formed by alternately laminating a plurality of piezoelectric layers made of the piezoelectric material represented by the general formula (1) and electrode arrangement layers including electrode portions constituting internal electrodes. Yes.

  The electrode arrangement layer preferably includes the electrode portion and an electrode non-forming portion in which an outer peripheral end portion of the electrode portion is recessed inward from an outer peripheral side surface of the ceramic laminate. In this case, the side electrodes that are alternately electrically connected to the internal electrodes (electrode portions) adjacent in the stacking direction can be easily formed.

The ceramic laminate preferably has a stress relaxation portion in a slit-like region recessed inward from the side surface of the ceramic laminate.
The stress relieving part is a part in the ceramic laminate, in which crystal grains constituting the piezoelectric layer are separated in the stacking direction, and the shape can be changed more easily than the piezoelectric layer.
The stress relaxation part can relieve stress accumulated in the stacking direction of the ceramic laminate. When the number of stacked layers is small, the stress relaxation effect by the stress relaxation portion is reduced. Therefore, the ceramic laminate preferably has 20 or more electrode arrangement layers. For the same reason, it is preferable that the stress relaxation portions are formed with an interval of 10 to 50 electrode arrangement layers in the stacking direction.
When the stress relaxation portions are formed at an interval of less than 10 electrode arrangement layers or at intervals exceeding the electrode arrangement layer 50 layers, in any case, the stress relaxation portions The stress relaxation effect may not be obtained sufficiently.

Specifically, the stress relaxation part is, for example, a slit-like space (groove part), a structure in which the slit-like space is filled with a material such as a resin having a lower Young's modulus than the piezoelectric material of the piezoelectric layer, and the piezoelectric A slit-like fragile layer made of the same material as the piezoelectric material of the body layer in a porous shape, a slit-like fragile layer formed of a material such as lead titanate different from the piezoelectric material of the piezoelectric layer, or polarization or It can be formed by a crack-like slit or the like intentionally generated by operation.
Preferably, the stress relaxation part is a slit-like groove part recessed inward from the side surface of the ceramic laminate. In this case, the stress relaxation part can be formed relatively easily.

  The stress relaxation part is formed on a side surface of the ceramic laminate. The stress relaxation portion can be partially formed on the side surface on which the side electrode is formed, for example, but can also be provided in the circumferential direction over the entire outer peripheral surface of the ceramic laminate.

Moreover, the said stress relaxation part can be formed, for example using the loss | disappearance material which lose | disappears at the time of baking.
As the disappearing material, for example, carbonized organic particles obtained by carbonizing powdered carbon particles, resin particles, powdered organic particles, or the like can be used.
In particular, when the carbon particles are used as the disappearing material, the stress relaxation portion can be formed with high shape accuracy by taking advantage of the characteristics of the carbon particles that the shape change due to heat is small.
On the other hand, when the carbonized organic particles are used as the disappearing material, the cost for forming the stress relaxation portion can be suppressed.
Examples of the organic particles include particles formed by pulverizing a resin material.
The carbonized organic particles are particles that are carbonized to some extent by removing a part of the water contained in the organic particles, and are in a state of fine particles having good fluidity and dispersibility.

  Further, the stress relaxation portion is formed by forming a slit-like region from a material that cracks when the laminated piezoelectric element is polarized or driven, and causing cracks when the laminated piezoelectric element is polarized or driven. You can also.

Moreover, it is preferable that the two electrode arrangement layers sandwiching the stress relaxation portion in the stacking direction are both electrically connected to the same side electrode. More preferably, it is preferably electrically connected to the side electrode on the positive electrode side.
In this case, the durability of the multilayer piezoelectric element can be improved.

Next, in manufacturing the laminated piezoelectric element, the raw material preparation step, the calcining step, the sheet forming step, the electrode printing step, the laminating step, the degreasing step, and the firing step. And the side electrode forming step.
In the raw material preparation step, the Pb source, Sr source, Zr source, Ti source, Y source, Nb source, and Sb source are represented by the general formula (1): (Pb _a Sr _b ) (Zr _c Ti _d (Y _e Nb _f Sb _g )) O ₃ (where 0.90 ≦ a + b ≦ 0.98, 0.03 ≦ b ≦ 0.08, c + d + e + f + g = 1, 0.980 ≦ c + d ≦ 0.998, 0.45 ≦ d) ≦ 0.48, 0.001 ≦ e + f ≦ 0.01, and 0.001 ≦ g ≦ 0.009) are mixed to prepare a raw material mixture.
By adjusting the raw material mixture at such a blending ratio, the piezoelectric layer made of the piezoelectric material represented by the general formula (1) can be formed after the firing step described later.

  Each element source such as Pb source, Sr source, Zr source, Ti source, Y source, Nb source, and Sb source is an oxide containing at least Pb, Sr, Zr, Ti, Y, Nb, or Sb, respectively. A compound such as a complex oxide can be employed.

In the calcining step, the raw material mixture is calcined at a temperature of 1000 ° C. or lower to obtain calcined powder.
When the heating temperature (calcining temperature) in the calcination step exceeds 1000 ° C., Pb of the main constituent material is evaporated and vaporized, resulting in a composition shift, and there is a possibility that a piezoelectric material having a desired composition cannot be obtained. The calcining temperature is preferably 800 ° C. or higher from the viewpoint of the lowest synthesis temperature for heating the raw material mixture to obtain a piezoelectric material having a desired composition. More preferably, the calcining temperature is 850 ° C. or higher and 950 ° C. or lower.

In the sheet forming step, a molded body sheet is obtained by adding at least a binder to the calcined powder, mixing and forming the sheet into a sheet shape.
In the said electrode printing process, the electrode material containing a conductive metal is printed on the area | region which forms the said electrode part, for example on the said molded object sheet, and an electrode printed sheet is obtained. At this time, it is possible to form the electrode non-formation portion on which the electrode material is not printed on the outer periphery of the electrode portion.
Moreover, when forming the said stress relaxation part, the said loss | disappearance material is printed on the said molded object sheet, and a loss | disappearance material printing sheet is obtained.

  Next, in the lamination step, a plurality of the electrode print sheets are laminated to produce a laminate. At this time, when forming the stress relaxation part, the disappearing material printing sheet is laminated between the electrode printing sheets at a desired interval. Thereafter, in the degreasing step, the laminate is degreased.

Next, in the firing step, the laminated body after the degreasing step is fired.
Thereby, the molded body sheet is sintered to form the piezoelectric layer composed of the piezoelectric material, and the electrode portion is formed in a region where the electrode material is printed. As a result, it is possible to obtain the ceramic laminate in which a plurality of the piezoelectric layers and the electrode arrangement layers are alternately laminated.
Moreover, when the said loss | disappearance material printing sheet is laminated | stacked, the said loss | disappearance material lose | disappears in the said baking process, and the said stress relaxation part (groove part) can be formed.

  In the side electrode forming step, the side electrode is formed on the ceramic laminate. The side electrode can be formed, for example, by baking a conductive metal such as Ag or an Ag alloy. In this way, the multilayer piezoelectric element can be obtained.

Further, the unit bonded stacked piezoelectric element can be formed by bonding a plurality of the stacked piezoelectric elements in the stacking direction.
Specifically, the stacked piezoelectric elements are stacked in the stacking direction, and the bonding portion is bonded with an adhesive or the like. Thereby, the unit bonded laminated piezoelectric element can be obtained.

  The laminated piezoelectric element and the unit bonded laminated piezoelectric element can be used for a fuel injection valve, for example.

Example 1
Next, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, in this example, a unit bonded stacked piezoelectric element 1 in which a plurality of stacked piezoelectric elements 2 are bonded in the stacking direction is manufactured. The stacked piezoelectric elements 2 are bonded to each other at the ends in the stacking direction, and a bonded portion 15 is formed between the stacked piezoelectric elements 2.

  As shown in FIGS. 2 and 3, the multilayer piezoelectric element 2 includes a ceramic laminate 20 in which a plurality of piezoelectric layers 21 and a plurality of electrode arrangement layers 22 and 23 are alternately laminated, and in the stacking direction. It has a pair of side surface electrodes 28 and 29 formed on the side surface which is a vertical surface. The electrode arrangement layers 22 and 23 are electrically connected to one of the side electrodes 28 and 29 in the electrode portions 221 and 231, respectively.

  As shown in FIGS. 2 and 3, the electrode arrangement layers 22 and 23 have no boundary with the upper and lower piezoelectric layers 21 sandwiching the electrode arrangement layers 22 and 23 in the electrode non-forming portions 222 and 232. . That is, the piezoelectric layer 21 and the electrode arrangement layers 22 and 23 are not laminated with a complete layered structure. However, in this specification, for convenience, in the ceramic laminate 20, no electrodes are formed on a plane in which the electrode portions 221 and 231 of the electrode arrangement layers 22 and 23 are extended in the horizontal direction (direction perpendicular to the lamination direction). The portions 222 and 232 exist, and the electrode arrangement layers 22 and 23 including the electrode portions 221 and 231 and the electrode non-formation portions 222 and 232 are handled as forming a laminated structure with the piezoelectric layer 21. Accordingly, each piezoelectric layer 21 is a region sandwiched between two adjacent electrode arrangement layers 22 and 23.

The piezoelectric layer 21 is represented by the general formula (1): (Pb _a Sr _b ) {Zr _c Ti _d (Y _e Nb _f Sb _g )} O ₃ , 0.90 ≦ a + b ≦ 0.98, 0. 03 ≦ b ≦ 0.08, c + d + e + f + g = 1, 0.980 ≦ c + d ≦ 0.998, 0.45 ≦ d ≦ 0.48, 0.001 ≦ e + f ≦ 0.01, and 0.001 ≦ g ≦ 0 .009 made of a piezoelectric material satisfying the relationship.
A piezoelectric layer 210 (dummy layer 210) having a larger thickness than the others is formed at both ends of the ceramic laminate 20.

Moreover, the ceramic laminated body 20 has the slit-shaped stress relaxation part 25 (groove part 25) dented inward from a side surface. In this example, the stress relaxation part 25 is a slit-like groove part recessed inward from the side surface of the ceramic laminated body 20, and is formed in the circumferential direction over the entire side surface of the ceramic laminated body 20.
Further, the electrode portions 221 of the two electrode arrangement layers 22 adjacent to each other with the stress relaxation portion 25 interposed therebetween are both electrically connected to the side electrode 28 on the positive electrode side. The other electrode arrangement layers 22 and 23 are electrically connected to alternately different side electrodes 28 and 29 in the electrode portions 221 and 231.

As shown in FIG. 1, in the unit bonded multilayer piezoelectric element 1, external electrodes 18 and 19 that electrically connect the side electrodes 28 and 29 formed on the same side surface of each ceramic laminate 20 are formed. Yes.
In FIG. 1 to FIG. 3, for convenience of drawing, the multilayer piezoelectric element is shown in a form in which the actual number of layers is omitted.

In manufacturing the laminated piezoelectric element of this example, a raw material preparation step, a calcination step, a sheet forming step, an electrode printing step, a lamination step, a degreasing step, a firing step, and a side electrode forming step are performed.
In the raw material blending step, the Pb source, Sr source, Zr source, Ti source, Y source, Nb source, and Sb source are represented by the general formula (1): (Pb _a Sr _b ) (Zr _c Ti _d (Y _e Nb _f Sb _g )) O ₃ (where c + d + e + f = 1, 0.90 ≦ a + b ≦ 0.97, 0.03 ≦ b ≦ 0.08, 0.980 ≦ c + d ≦ 0.998, 0.45 ≦ d ≦ 0.48, 0.001 ≦ e + f ≦ 0.01, and 0.001 ≦ g ≦ 0.01) to prepare a raw material mixture.

In the calcining step, the raw material mixture is calcined at a temperature of 1000 ° C. or lower to obtain calcined powder.
In the sheet forming step, at least a binder is added to the calcined powder and mixed to form a sheet, thereby obtaining a formed body sheet.
In the electrode printing process, electrode materials 220 and 230 containing a conductive metal are printed on the region 41 where the electrode part is formed on the molded sheet 210 to obtain the electrode printed sheets 31 and 32 (FIGS. 4 and 4). 5).

In the lamination step, a plurality of electrode print sheets 31 and 32 are laminated to produce a laminate 40 (4) (see FIG. 7). Thereafter, in the degreasing step, the laminate is degreased.
Next, in the firing step, the laminate after the degreasing step is fired to obtain a ceramic laminate 20 (see FIGS. 2 and 3).
In the side electrode forming step, side electrodes 28 and 29 are formed on the ceramic laminate 20 (see FIGS. 2 and 3).

Moreover, in this example, in order to form a stress relaxation part, a loss | disappearance material printing process is performed.
In the disappearing material printing step, the disappearing material 250 that disappears by firing is printed on the part that finally becomes the stress relaxation portion on the molded body sheet 210 to form the disappearing material printing sheet 33. And in the said lamination process, the loss | disappearance material printing sheet 33 is arrange | positioned between the electrode printing sheets 31 and 32 laminated | stacked a predetermined number, and the laminated body 40 is produced (refer FIG. 7).

  Hereinafter, the manufacturing method of the multilayer piezoelectric element of this example will be described in detail with reference to FIGS. 1 to 10 and FIG. In this example, a laminated piezoelectric element is obtained by performing from the preparation 1 of the process diagram shown in FIG. 12 to the side electrode baking.

<Raw material preparation process>
First, a ceramic raw material powder such as lead zirconate titanate (PZT) serving as a piezoelectric material was prepared. Specifically, Pb ₃ O ₄ , SrCO ₃ , ZrO ₂ , TiO ₂ , Y ₂ O ₃ , Nb ₂ O ₅ and Sb ₂ O ₃ are prepared as starting materials, and these starting materials are represented by the above general formula (1 ) (Pb _a Sr _b ) {Zr _c Ti _d (Y _e Nb _f Sb _g )} O ₃ Weighed in a stoichiometric ratio. Next, the mixture was wet-mixed and pulverized, and then dried at a temperature of 120 ° C.

<Calcination process>
Next, the raw material mixture was calcined at a temperature of 850 ° C. for 7 hours. Next, the calcined powder was coarsely pulverized with a rake machine. Next, the calcined powder was wet pulverized by a pearl mill, and the pulverized product of the calcined powder (particle diameter (D50 value): 0.65 ± 0.05 μm) was dried.

<Molding process>
Next, a solvent, a binder, a plasticizer, a dispersant, etc. are added to the calcined powder and mixed by a ball mill, and the resulting calcined powder slurry is vacuum degassed while being stirred by a stirrer in a vacuum apparatus. The viscosity was further adjusted.
Next, a calcined powder slurry was applied onto a carrier film by a doctor blade method to form a long molded sheet (green sheet) having a thickness of 80 μm. The green sheet was cut into a predetermined size to produce a wide green sheet (sheet molding).
In addition to the doctor blade method used in this example, an extrusion molding method and various other methods can be employed as the green sheet molding method.

<Electrode printing process>
Next, in the electrode printing step, as shown in FIGS. 4 and 5, the electrode materials 220 and 230 serving as the electrode portions are printed on the green sheet 210, and the first electrode printing sheet 31 and the second electrode printing sheet 32. Various types of electrode printing sheets were prepared (electrode printing).
Below, preparation of an electrode printing sheet is further demonstrated.
As shown in FIG. 4, in producing the first electrode printed sheet 31, the electrode material 220 was printed on a portion that finally becomes an electrode portion in the printing region 41 on the green sheet 210. Thereby, the 1st electrode printing sheet 31 was formed.
Further, as shown in FIG. 5, in forming the second electrode print sheet 32, the electrode material 230 was printed on the portion to be an electrode portion in the print region 41 on the green sheet 210 in the same manner as the first electrode print sheet. . Thereby, the 2nd electrode printing sheet 32 was formed.
In the first electrode printing sheet and the second electrode printing sheet, the electrode materials 220 and 230 were printed so that the electrode materials 220 and 230 were exposed at different ends in the printing region 41.
In this example, a pasty Ag / Pd alloy was used as the electrode material. In addition to the above, simple substances such as Ag, Pd, Cu, and Ni, and alloys such as Cu / Ni can be used.

<Disappearing material printing process>
Next, in order to provide the stress relaxation part 25 (refer FIG.2 and FIG.3) on the side surface of the ceramic laminated body 20, as shown in FIG. 6, the vanishing material printing process which forms the vanishing material printing sheet 33 was performed.
As shown in the figure, in the printing region 41 on the green sheet 210, a disappearing material 250 that disappears by firing was printed on a portion that finally becomes a stress relaxation portion. Thereby, the disappearance material printing sheet 33 was produced.
In this example, a material made of carbon particles was used as the disappearing material. In addition to carbon particles, carbonized organic particles can also be used. The carbonized organic particles can be obtained by carbonizing powdered organic particles, or by pulverizing the carbonized organic material. Furthermore, as the organic substance, a polymer material such as a resin can be used.

Further, in the electrode printing process and the disappearing material printing process, a plurality of electrode materials 220 and 230 and the disappearing material 250 are printed on one green sheet in order to produce a plurality of laminated bodies by the laminating and cutting processes described later. did.
Further, the electrode materials 220 and 230 and the disappearing material layer 250 were printed with a gap 42 as shown in FIGS. 4 to 6 so as to avoid a portion to be cut in the cutting process. That is, printing was performed by providing a gap 42 between adjacent print areas 41 on the green sheet 210.

<Lamination process>
Next, as shown in FIG. 7, the first electrode printing sheet 31, the second electrode printing sheet 32, and the disappearing material printing sheet 33 were stacked in a predetermined order with the printing regions 41 aligned in the stacking direction.
At this time, the 1st electrode printing sheet 31 and the 2nd electrode printing sheet 32 were laminated | stacked alternately, and the loss | disappearance material printing sheet 33 was inserted and laminated | stacked in the position which wants to form the said stress relaxation part.
Specifically, in this example, the disappearance material printing sheet 33 is laminated for every 11 layers of the laminated structure of the first electrode printing sheet 31 and the second electrode printing sheet 32, and the first electrode printing sheet 31 and the second electrode are laminated. The printing sheets 32 were stacked so that the total number of sheets was 95.
At this time, the first electrode print sheet 31 and the second electrode print sheet 32 were laminated so that the electrode materials 220 and 230 were alternately exposed on the opposing end surfaces of the print region 41. However, for the two electrode print sheets sandwiching the disappearing material print sheet 33 adjacent to each other, a print sheet having the same electrode material formation pattern (first electrode print sheet 31) is used, and two opposing end surfaces of the print region 41 are used. Of these, the electrode material 220 was laminated so as to be exposed on the same end face. That is, as shown in FIG. 9, the first electrode printing sheet 31 is arranged above and below the disappearing material printing sheet 33 in such a direction that the electrode material 220 is exposed on the same side surface after the cutting process described later.
Moreover, the green sheet 210 which has not printed the electrode material or the loss | disappearance material was laminated | stacked on the both ends of the laminated body. And the sheet | seat laminated | stacked in this way was heated at 100 degreeC, and it pressurized by 50 Mpa in the lamination direction, and the preliminary | backup laminated body 40 was formed. In FIG. 7, for the convenience of drawing, the preliminary laminated body is shown in a form in which the actual number of laminated layers is omitted.

Next, as shown in FIGS. 8 to 10, the formed preliminary laminated body was cut in the lamination direction along the cutting position 43 to form the intermediate laminated body 4 (cutting step).
The preliminary laminated body 40 may be cut for each intermediate laminated body 4 or may be cut including a plurality of intermediate laminated bodies 4. In this example, each intermediate laminate 4 was cut and cut so that the electrode materials 220 and 230 and the disappearing material layer 250 were exposed on the side surfaces of the intermediate laminate 4.
In FIG. 9 and FIG. 10, the preliminary laminated body and the intermediate laminated body are shown in a form in which the actual number of laminated layers is omitted for the convenience of drawing.

<Degreasing process>
Next, 90% or more of the binder resin contained in the green sheet of the intermediate laminate was removed by heating (degreasing). In heating, the temperature was gradually raised to 500 ° C. over 80 hours and held for 10 hours.

<Baking process>
Next, the degreased intermediate laminate was fired. Firing was performed by gradually raising the temperature to 1070 ° C. over 18 hours, holding for 2 hours, and then gradually cooling.
In this way, as shown in FIGS. 2 and 3, the piezoelectric laminate 21 and the electrode arrangement layers 22 and 23 are alternately laminated, and the ceramic laminate 20 having the slit-like stress relaxation portions 25 is obtained. It was.

<Side electrode formation process>
After firing, the entire surface was polished to produce a ceramic laminate 20 having a length of 6 mm, a width of 6 mm, and a height of 4.4 mm, and a pair of side electrodes 28 and 29 were baked so as to sandwich both side surfaces thereof.
At this time, the electrode portions 221 and 222 of the electrode arrangement layers 22 and 23 are electrically connected to the side electrodes 28 and 29 on the different side surfaces alternately. However, the electrode portions 221 of the two electrode arrangement layers 22 sandwiching the stress relaxation portion 25 are electrically connected to the side electrode 28 on the same side. In this example, the side electrode 28 on the side where the electrode portions 221 of the two electrode arrangement layers 22 sandwiching the stress relaxation portion are connected as the positive electrode.

  As described above, as shown in FIGS. 2 and 3, the ceramic laminate 20 is formed by alternately laminating the plurality of piezoelectric layers 21 and the plurality of electrode arrangement layers 22 and 23, and is formed on the side surface thereof. The multilayer piezoelectric element 2 having the stress relaxation portion 25 and the pair of side surface electrodes 28 and 29 was produced.

Next, a plurality of multilayer piezoelectric elements obtained in this way are bonded to produce a unit bonded multilayer piezoelectric element.
First, a silicone resin adhesive was prepared as an adhesive for joining the laminated piezoelectric elements. This silicone resin adhesive contains a linear organopolysiloxane containing a vinyl group as a main ingredient of a silicone rubber composition, and contains an organohydrogenpolysiloxane as a crosslinking agent. In this example, a silicone resin adhesive having an adhesive strength after curing of 1.3 MPa or more was employed.

As shown in FIG. 11, the adhesive 5 was applied to the bonding surface of the multilayer piezoelectric element 2 with a thickness of 1 μm or less, and the multilayer piezoelectric elements 2 were bonded to each other in the stacking direction. In this example, six laminated piezoelectric elements 2 were joined. Thereafter, pressure was applied from the stacking direction, and the adhesive was cured by holding at a temperature of 180 ° C. for 1 hour.
In this way, a unit bonded multilayer piezoelectric element 1 in which six multilayer piezoelectric elements 2 were bonded in the stacking direction was produced. In FIG. 11, for convenience of drawing, the number of stacked piezoelectric elements in the unit-bonded stacked piezoelectric element is omitted, and the number of piezoelectric layers in the stacked piezoelectric element and the stress relaxation portion are shown. Is omitted.

Further, as shown in the figure, after the laminated piezoelectric elements 2 are joined, the external electrodes 18 for electrically connecting the positive side electrodes 28 formed on each laminated piezoelectric element 2 to each other, and the negative side electrodes External electrodes 19 were formed to electrically connect 29 to each other. The external electrodes 28 and 29 were formed by baking a conductive metal such as Ag.
In this way, as shown in FIG. 1, a unit bonded laminated piezoelectric element 1 in which a plurality of laminated piezoelectric elements 2 were bonded was produced.

In this example, the composition in the raw material blending process was changed to form a piezoelectric layer composed of a plurality of piezoelectric materials having different compositions.
Specifically, first, the starting material is weighed by changing the value of b (Sr amount) in the general formula: (Pb _0.94 Sr _b ) (Zr _0.529 Ti _0.454 (Y _0.0025 Nb _0.0025 Sb _0.006 )) O ₃ . Performed the same operation as described above to produce 11 types of unit-bonded laminated piezoelectric elements (samples E1 to E7 and samples C1 to C4). The value of b is shown in Table 1 described later.

In addition, the starting material was weighed by changing the value of a + 0.05 (Pb + Sr amount) in O ₃ in the general formula: (Pb _a Sr _0.05 ) (Zr _0.529 Ti _0.454 (Y _0.0025 Nb _0.0025 Sb _0.006 )). The same operation was performed to produce 13 types of unit-bonded laminated piezoelectric elements (samples E8 to E16 and samples C5 to C8). The value of a + 0.05 is shown in Table 2 below.

In addition, the starting material was weighed by changing the value of g (Sb amount) in the general formula: (Pb _0.94 Sr _0.05 ) (Zr _0.529 Ti _0.454 (Y _0.0025 Nb _0.0025 Sb _g )) O ₃ , and the others were the same as above Operation was performed to produce 14 types of unit-bonded laminated piezoelectric elements (samples E17 to E25 and samples C9 to C13). The value of g is shown in Table 3 below.

Also, the starting material is changed by changing the value of e + f (Y + Nb amount, e: f = 1: 1) in the general formula: (Pb _0.94 Sr _0.05 ) (Zr _0.529 Ti _0.454 (Y _e Nb _f Sb _0.006 )) O ₃ Weighed and performed the other operations in the same manner as above to produce 14 types of unit-bonded laminated piezoelectric elements (samples E26 to E35 and samples C14 to C17). The value of e + f is shown in Table 4 described later.

Next, the displacement amount was measured for the unit bonded laminated piezoelectric elements (samples E1 to E35 and samples C1 to C17) obtained as described above.
Specifically, a voltage of 150 V was applied to each sample (unit bonded stacked piezoelectric element) while applying a load of 500 N in the stacking direction. The displacement of each sample at this time was measured with a laser displacement meter. The measurement was performed on two points, and the average of these was used as the displacement amount of each sample.
The displacement was measured at room temperature, but was measured after aging for about 20 with each sample being driven in advance. The results are shown in Tables 1 to 4 and FIGS.

As shown in Tables 1 to 4 and FIGS. 13 to 16, the general formula (1): (Pb _a Sr _b ) {Zr _c T _{i d} (Y _e Nb _f Sb _g )} O ₃ (c + d + e + f + g = 1, 0. 90 ≦ a + b ≦ 0.98, 0.03 ≦ b ≦ 0.08, 0.980 ≦ c + d ≦ 0.998, 0.45 ≦ d ≦ 0.48, 0.001 ≦ e + f ≦ 0.01, and 0 Sample E1 to Sample E35 on which a piezoelectric layer composed of a piezoelectric material having a composition represented by .001 ≦ g ≦ 0.009) showed a large displacement amount of 40 μm or more and was excellent in displacement performance. On the other hand, Sample C1 to Sample C17 outside the above composition range were insufficient in displacement performance.

  Therefore, according to this example, the piezoelectric material represented by the general formula (1) can exhibit excellent displacement performance, and the laminated piezoelectric element and the unit bonded laminated piezoelectric element using such a piezoelectric material are: It can be seen that the displacement performance excellent in practical use can be exhibited.

DESCRIPTION OF SYMBOLS 1 Unit junction laminated type piezoelectric element 15 Junction part 18 External electrode 19 External electrode 2 Laminated type piezoelectric element 21 Piezoelectric layer 22 Electrode arrangement layer 23 Electrode arrangement layer 25 Stress relaxation part 28 Side electrode 29 Side electrode

Claims (4)

A piezoelectric material represented by the general formula (1): (Pb _a Sr _b ) {Zr _c Ti _d (Y _e Nb _f Sb _g )} O ₃ ,
0.90 ≦ a + b ≦ 0.98,
0.03 ≦ b ≦ 0.08,
c + d + e + f + g = 1,
0.980 ≦ c + d ≦ 0.998,
0.45 ≦ d ≦ 0.48,
0.001 ≦ e + f ≦ 0.01, and 0.001 ≦ g ≦ 0.009
A piezoelectric material characterized by satisfying this relationship. A ceramic laminate formed by alternately laminating a plurality of piezoelectric layers made of a piezoelectric material that can be expanded and contracted by applying a voltage and an electrode arrangement layer including an electrode portion constituting an internal electrode, and a side surface of the ceramic laminate In a laminated piezoelectric element having a pair of side electrodes formed in
The multilayer piezoelectric element, wherein the piezoelectric layer is mainly composed of the piezoelectric material according to claim 1. A ceramic laminate formed by alternately laminating a piezoelectric layer made of a piezoelectric material that can be expanded and contracted by applying a voltage and an electrode arrangement layer including an electrode portion constituting an internal electrode, and a side surface of the ceramic laminate In a method for manufacturing a laminated piezoelectric element having a pair of side electrodes formed,
The Pb source, Sr source, Zr source, Ti source, Y source, Nb source, and Sb source are _expressed by the general formula (1): (Pb _a Sr _b ) (Zr _c Ti _d (Y _e Nb _f Sb _g )) O ₃ (provided that 0.90 ≦ a + b ≦ 0.98, 0.03 ≦ b ≦ 0.08, c + d + e + f + g = 1, 0.980 ≦ c + d ≦ 0.998, 0.45 ≦ d ≦ 0.48,. 001 ≦ e + f ≦ 0.01 and 0.001 ≦ g ≦ 0.009) are mixed at a mixing ratio to prepare a raw material mixture,
A calcining step of calcining the raw material mixture at a temperature of 1000 ° C. or less to obtain calcined powder;
A sheet molding step of obtaining a molded body sheet by adding at least a binder to the calcined powder and mixing to form a sheet; and
An electrode printing step of obtaining an electrode printing sheet by printing an electrode material containing a conductive metal on the molded body sheet,
A laminating step of laminating a plurality of the electrode print sheets to produce a laminate;
A degreasing step for degreasing the laminate,
A firing step of firing the laminate after the degreasing step to obtain the ceramic laminate;
A method for producing a multilayer piezoelectric element, comprising: a step of forming a side electrode on the ceramic laminate.   A unit-bonded stacked piezoelectric element comprising a plurality of the stacked piezoelectric elements according to claim 2 or a plurality of the stacked piezoelectric elements obtained by the manufacturing method according to claim 3 bonded in a stacking direction.

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