JPH11278929A - Porcelain composition for integrally baked type laminated piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a porcelain composition for an integrally baked type laminated piezoelectric actuator capable of being baked at a low temperature range capable of using an inexpensive Ag/Pd, etc., as an internal electrode. SOLUTION: This porcelain composition is represented by the formula: xPb(Zn1/3 Ta2/3 )O3 -yPbTiO3 -zPbZrO3 and composed of a region surrounded by respective points of A(x, y, z)=(0.45, 0.33, 0.22), B(x, y, z)=(0.30, 0.47, 0.22), C(x, y, z)=(0.03, 0.47, 0.50), D(x, y, z)=(0.003, 0.40, 0.57), E(x, y, z)=(0.10, 0.33, 0.57)and F(x, y, z):(0.30, 0.30, 0.40) in a ternary system triangular diagram represented by molar ratios in which Pb(Zn1/3 Ta2/3 )O3 is (x), PbTiO3 is (y) and PbZrO3 is (z) and further contains 0.1-2.0 mol.% of one or more kinds of components selected from the group consisting of W, Nb and Fe therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a porcelain composition for an integrally fired laminated piezoelectric actuator.

[0002]

2. Description of the Related Art An integrated firing type laminated piezoelectric actuator is
It has a configuration as shown in FIG.
Indicates a piezoelectric layer, 2 indicates an external electrode, 3 indicates an insulator, and 4 indicates an internal electrode. The integrated firing type laminated piezoelectric actuator having such a configuration is formed by forming an internal electrode material on a green sheet formed of a material exhibiting an electrostrictive effect and an organic material by screen printing or the like, laminating / compressing, then firing integrally, and Has a structure in which the internal electrodes are connected to every other layer by the external electrodes formed on the substrate.

Conventionally, green sheets include Pb (Ni
_{1/3 Nb 2/3) O 3 -PbTiO 3} -PbZrO 3 series, Pb
A piezoelectric porcelain composition containing a PbTiO ₃ -PbZrO ₃ system as a main component such as a (Mg _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ -PbZrO ₃ system and adding a third component such as a composite perovskite is used. I was However, in recent years, piezoelectric actuators have been required to be miniaturized, driven at a low voltage, and driven at high speeds, and piezoelectric actuators have been reduced in size, multi-layered, and thinned at intervals between layers. It has been desired to reduce the capacity, reduce the loss, and generate heat.

In order to solve the problems of increasing the capacity of a piezoelectric actuator using the above-described piezoelectric ceramic composition, generating heat at the time of high-speed driving, and further solving the problems of hysteresis and drift of electric strain of the piezoelectric actuator, JP 2
JP-67773 discloses a general formula

## STR2 ## xPb (Zn _1/3 Ta _2/3 ) O ₃ -yPbTiO ₃
Represented by -ZPbZrO ₃ and Pb (Zn _1/3 Ta _2/3) the O ₃ x, PBT
In a ternary triangular chart showing a molar ratio where iO ₃ is y and PbZrO ₃ is z, A (x, y, z) = (0.45, 0.33, 0.22) B (x, y, z) = (0.30, 0.47, 0.22) C (x, y, z) = (0.03, 0.47, 0.50) D (x, y, z) = (0.4) 03, 0.40, 0.57) E (x, y, z) = (0.10, 0.33, 0.57) A region surrounded by each point of A porcelain composition is disclosed.

[0005]

The piezoelectric porcelain composition for an actuator disclosed in this publication has a large electrostriction as a material for a piezoelectric actuator, a low dielectric constant, a low loss, and a hysteresis of the electrostriction. Although it has an excellent feature that drift is small, a firing temperature of 1200 to 1300 ° C. is required when manufacturing a piezoelectric actuator. As described above, the piezoelectric actuator is manufactured by integral firing in which the sheets on which the internal electrodes are printed are stacked and fired. However, if the firing temperature is as high as 1200 to 1300 ° C., the metal usable for the internal electrodes is expensive such as Pt. It is limited to metal and has a problem in terms of cost and the like.

Accordingly, an object of the present invention is to provide a porcelain composition for a monolithically fired laminated piezoelectric actuator that can be fired in a low temperature range and that can use inexpensive Ag / Pd or the like as internal electrodes. is there.

[0007]

That is, the present invention provides a compound represented by the following general formula:

## STR3 ## xPb (Zn _1/3 Ta _2/3 ) O ₃ -yPbTiO ₃
-PbZrO ₃ , wherein Pb (Zn _1/3 Ta _2/3 ) O ₃ is x, Pb
In a ternary triangular chart showing a molar ratio where TiO ₃ is y and PbZrO ₃ is z, A (x, y, z) = (0.45, 0.33, 0.22) B (x, y, z) = (0.30, 0.47, 0.22) C (x, y, z) = (0.03, 0.47, 0.50) D (x, y, z) = (0.4) 03, 0.40, 0.57) E (x, y, z) = (0.10, 0.33, 0.57) F (x, y, z) = (0.30, 0.30, 0.40), and contains 0.1 to 2.0 mol% of one or more components selected from the group consisting of W, Nb and Fe. The porcelain composition for an integrally fired laminated piezoelectric actuator is characterized in that:

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The porcelain composition for an integrally fired laminated piezoelectric actuator of the present invention is composed of Pb (Zn _1/3 Ta _2/3 ) O.
₃ is a ternary triangular chart shown in FIG. 2 in which a molar ratio is represented by x, PbTiO ₃ by y, and PbZrO ₃ by z, and A (x, y, z) = (0.45, 0.33, 0.3). 22) B (x, y, z) = (0.30, 0.47, 0.22) C (x, y, z) = (0.03, 0.47, 0.50) D (x, y, z) = (0.03, 0.40, 0.57) E (x, y, z) = (0.10, 0.33, 0.57) F (x, y, z) = ( 0.30, 0.30, 0.40) in the composition consisting of a region surrounded by each point of 0.1, 2 or more components selected from the group consisting of W, Nb and Fe. 2.0 mol%.

Here, in the triangular chart shown in FIG.
b (Zn _1/3 Ta _2/3 ) O ₃ , PbTiO ₃ , PbZrO ₃
Points, respectively A, B, C, D, was a composition enclosed in E and F, the electric strain out of this range is 450 × 10 ^-12
This is because it is smaller than m / V and is not suitable as a porcelain composition for an integrally fired laminated piezoelectric actuator.

Further, the porcelain composition for an integrally fired laminated piezoelectric actuator of the present invention contains Pb (Zn _1/3
Ta _2/3 ) O ₃ , PbTiO ₃ , and PbZrO ₃ , and 0.1 to 2.0 mol% of one or more components selected from the group consisting of W, Nb and Fe. It becomes. By blending W, Nb and / or Fe,
When firing to produce a laminated piezoelectric actuator, the firing temperature can be reduced to about 1000 to 1150 ° C., preferably to about 1100 ° C. or less, whereby Pt is used as an internal electrode material of the laminated piezoelectric actuator.
Ag / Pd or the like which is inexpensive as compared with the above can be used. If the compounding amount of W, Nb and / or Fe is less than 0.1 mol, the firing temperature is set to A
It is not preferable because g / Pd or the like cannot be lowered to a usable temperature range of 1000 to 1150 ° C. On the other hand, if the compounding amount of W, Nb and / or Fe exceeds 2.0 mol, the electric strain becomes small, and the piezoelectric characteristics are undesirably deteriorated.

The porcelain composition for a monolithically fired laminated piezoelectric actuator of the present invention has good properties such that the electrostriction, the relative dielectric constant and the dielectric loss are substantially the same as those described in JP-A-2-67773. , While maintaining the temperature, the temperature for integral firing when producing the laminated piezoelectric actuator is set to 100.
Since the temperature can be lowered to a temperature range of 0 to 1150 ° C., thereby making it possible to use an inexpensive internal electrode material, it is optimal as a ceramic composition for a laminated piezoelectric actuator.

The porcelain composition for an integrally fired laminated piezoelectric actuator of the present invention can be obtained by an ordinary method for producing new ceramics. For example, PbO, TiO ₂ , Z
rO ₂ , ZnO, Ta ₂ O ₅ , WO ₃ , Nb ₂ O ₅ , Fe ₂ O ₃
Are weighed and mixed at a predetermined ratio so as to fall within the range defined by the above general formula. Next, the resulting mixture was 800
After calcination for 1 to 6 hours in a temperature range of １０００1000 ° C., it can be obtained by grinding.

Using the porcelain composition for an integrally fired laminated piezoelectric actuator of the present invention obtained as described above, an integrally fired laminated piezoelectric actuator can be manufactured in accordance with a normal manufacturing method of an integrally fired laminated piezoelectric actuator. . For example, a predetermined amount of a binder is added to the porcelain composition for an integrally fired laminated piezoelectric actuator of the present invention to produce a green sheet, and an internal electrode material is formed on the obtained green sheet by screen printing or the like. Later, 1
By integrally firing in a temperature range of 000 to 1150 ° C., an integrally fired multilayer piezoelectric actuator can be manufactured.

As a raw material of the ceramic composition for an integrally fired laminated piezoelectric actuator of the present invention, a compound which decomposes into the above oxide by heating or a compound of these compounds can be used. As these raw materials, for example, carbonates, acetates and the like can be used.

[0015]

EXAMPLES The porcelain composition for an integrally fired laminated piezoelectric actuator of the present invention will be further described below with reference to examples. Examples PbO, TiO ₂ , ZrO ₂ , ZnO, Ta ₂ O ₅ , W
₂ O ₃ , Nb ₂ O ₅ , and Fe ₂ O ₃ were used as raw materials, weighed so as to have the composition shown in Table 1, wet-mixed using a pot mill, and then calcined at 900 ° C. for 2 hours. 200 g of this calcined powder
5 g of polyvinyl alcohol as a binder was added to the mixture, and after granulation, a diameter of 30 mm was obtained at a molding pressure of 1 ton / cm ² ,
It was formed into a disk having a thickness of 2 mm. 1100 ° C
At a temperature of 2 hours to obtain a disc-shaped sintered body. The diameter of the sintered body after firing was about 24 mm. Next, both surfaces of the obtained sintered body were polished to a thickness of 1.0.
mm ([5] in FIG. 3), and the electrode (silver) (6) in FIG. 3) was baked to obtain a specimen. The obtained specimen was polarized in silicon oil by applying an electric field of 20 kV / cm at 60 ° C.

[0016] The specimens were polarized as described above, density, dielectric constant was measured dielectric loss, electrostrictive and d _33. The results obtained are set forth in Table 1 below. In addition,
In Table 1, * indicates a comparative product.

[0017]

[Table 1]

[0018]

[Table 2]

In Table 1, the dielectric loss is measured with an LCZ meter. The relative permittivity is obtained by measuring the capacitance with an LCZ meter and calculating according to the following formula:

Ε _r = (Cf × t) / (S × ε ₀ ) where Cf: capacitance (F) t: electrode interval (m) S: electrode area (m ² ) ε ₀ : in vacuum Dielectric constant [8.854 × 10 ⁻¹² (F /
m)] Further, as for the electrostriction, a voltage of 1000 V is applied to the specimen (7) in a configuration as shown in FIG. 4 using an optical non-contact displacement meter (8) having a resolution of 0.01 μm. The amount of displacement at the time of performing was measured. Also, d ₃₃ is calculated from the measured value of the electrostriction according to the following formula:

D ₃₃ = [electrostriction (μm)] / [applied voltage (V) at the time of measuring voltage distortion] × 10 ⁻⁶ (m / V)

As is clear from Table 1, the porcelain composition for an integrally fired laminated piezoelectric actuator of the present invention has a thickness of 1100.
In a specimen fired at a low temperature of ℃, the electrostriction when a voltage of 1000 V is applied in the thickness direction (polarization direction) is as large as 0.45 to 0.73 μm, the relative dielectric constant is as low as 1550 or less, and The dielectric loss was as low as 2.6% or less.

[0021]

As described above, if a monolithic laminated piezoelectric actuator is manufactured using the ceramic composition for a monolithically laminated monolithic piezoelectric actuator of the present invention, a small-sized, low-capacity, low-voltage driven, large displacement laminated piezoelectric actuator can be obtained. And the amount of heat generated during high-speed driving of the multilayer piezoelectric actuator is:
It is possible to use an inexpensive material such as Ag / Pd as the internal electrode material while maintaining that of the composition described in JP-A-2-67773.

[Brief description of the drawings]

FIG. 1 is a schematic view of an integrally fired laminated piezoelectric actuator.

_{Pb (Zn 1/3 Ta 2/3} ) in FIG. 2 integrally sintered multilayer piezoelectric actuator porcelain composition of the present invention O ₃ component,
It is a ternary chart of a ternary system showing the molar ratio of the PbTiO ₃ component and the PbZrO ₃ component.

FIG. 3 is a schematic view of a specimen obtained in an example.

FIG. 4 is a schematic view of an apparatus for measuring the electrostriction of a specimen in an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric layer 2 External electrode 3 Insulator 4 Internal electrode 5 Sintered body 6 Electrode 7 Specimen 8 Optical non-contact displacement meter

Claims (3)

[Claims] 1. The general formula: ## STR1 ## xPb (Zn _1/3 Ta _2/3 ) O ₃ -yPbTiO ₃
-PbZrO ₃ , wherein Pb (Zn _1/3 Ta _2/3 ) O ₃ is x, Pb
In a ternary triangular chart showing a molar ratio where TiO ₃ is y and PbZrO ₃ is z, A (x, y, z) = (0.45, 0.33, 0.22) B (x, y, z) = (0.30, 0.47, 0.22) C (x, y, z) = (0.03, 0.47, 0.50) D (x, y, z) = (0.4) 03, 0.40, 0.57) E (x, y, z) = (0.10, 0.33, 0.57) F (x, y, z) = (0.30, 0.30, 0.40), and contains 0.1 to 2.0 mol% of one or more components selected from the group consisting of W, Nb and Fe. A porcelain composition for an integrally fired laminated piezoelectric actuator, comprising: 2. The porcelain composition for an integrally fired multilayer piezoelectric actuator according to claim 1, wherein the composition can be fired at a firing temperature of 1000 to 1150 ° C. 3. The calcined product has an electrostriction of 450 × 10 ⁻¹² m /
The porcelain composition for a monolithic laminated piezoelectric actuator according to claim 1 or 2, wherein the porcelain composition has a relative dielectric constant of 2,000 or less and a dielectric loss of 2.5% or less.