JPH02299276A - Piezoelectric ceramic composition - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric porcelain compound large in electrostriction and mechanical displacement and small in hysteresis by a method wherein La2O3, Co2O3, and MnO are added as secondary compositions to a specific extent respectively to a chemical compound whose basic composition is specified. CONSTITUTION:0.01-0.3wt.% La2O3, 0.01-0.3wt.% Co2O3, and 0.005-0.15wt.% MnO are added to a basic composition represented by a formula, Pb[Ni1/3Nb2/3)A (Sb1/2Nb1/2)BZrCTiD]O3, to be contained. In the formula concerned, an equation, A+B+C+D=1, is satisfied, and inequalities, 0.300<=A<=0.550, 0.002<=B<=0.050, 0.120<=C<=0.290, and 0.280<=D<=0.408, are satisfied. By this setup, a piezoelectric ceramic composition large in both electrostriction and mechanical displacement and small in voltage-displacement hysteresis can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a piezoelectric ceramic composition, and is particularly suitable for a voltage-driven voltage displacement element that requires large mechanical displacement and high-precision position control by voltage application. The present invention relates to a piezoelectric ceramic composition.

[Prior Art] In recent years, the m-magnetic type has been replaced. A new type of drive source is the practical use of voltage-driven piezoelectric displacement elements (hereinafter referred to as displacement elements) that utilize the electrostrictive effect of piezoelectric ceramics to convert electrical energy into mechanical energy.

Progress has been made in many fields, including micro position control equipment. As shown in FIG. 2, this type of displacement element is known to have a bimorph structure in which piezoelectric ceramic plates 2 and 2' having electrodes sandwiched between them are attached to a metal elastic plate 1. There is.

When a DC or AC voltage is applied to this displacement element, a mechanical displacement dS occurs due to an electrostrictive effect (in this case, a piezoelectric transverse effect).
Or ds2 occurs. Although this mechanical displacement depends on the application and the mechanism used when it is installed, it is generally desirable to have it as large as possible in terms of its function as a displacement element, and it is also desirable in terms of high-precision position control or quality as a device. It is desirable that the voltage-displacement hysteresis be as small as possible. For example, for two-mechanical displacement, piezoelectric device compositions with larger electrostrictive effects are considered advantageous.

[Problems to be Solved by the Invention] Conventionally, piezoelectric ceramic compositions of this type have been used, for example, P b (N i , . . . ) having a relatively large piezoelectric constant d31.

3 such as Nb23)03 PbZrO3-PbTiO3
There are component-based ones.

However, although a certain degree of mechanical displacement can be obtained with conventional compositions,? J Pressure displacement displacement hysteresis was large, and its use as a displacement element was limited to an extremely narrow range. Therefore, a piezoelectric ceramic material that can be applied to a wide range of applications as a displacement element, provides a larger mechanical displacement, and has a smaller voltage-displacement hysteresis has been desired.

Therefore, one technical problem of the present invention is to provide a piezoelectric ceramic composition which can fully meet such demands, and which has a large electrostrictive effect when applied with a voltage and has a small hysteresis, so that it can be applied to a wide range of uses as a displacement element. There is a particular thing.

[Means for Solving the Problems] The piezoelectric ceramic composition of the present invention has the general formula P b [(N i 1., N b2 .]) A
(Sb12Nb1,2)B Z r. Ti, ]O, (where A+B+C+D-1)0. For the basic composition satisfying 300≦A≦0.550 0.002≦B≦0.050 0, 120≦C≦0.290 0.280≦D ffi 0.408, La2O3 is added from 0.01 to 0.
．． 3 layers]%, Co2O3 0. 0.01 to 0.3% by weight.

It is characterized by containing 0.005 to 0.15% by weight of MnO.

In addition, 0.300 > A, A >0.550,
B>0.050.

0.120 >C,A, >0.290, 0.280
>D, the basic composition consisting of D>0.408 and the subcomponent L a 20 N .

CO□0. are each more than 0.03% by weight, and MnO is 0.
．． For compositions with a weight of 15 or more than 96, the amount of electrostriction.

Mechanical displacement decreases, therefore, it is not preferable as a composition for the intended displacement element, and 0.002>B
Each of Ml component La20g and CO20x is 0°0
A composition containing less than 1% by weight of the electrostrain amount did not show a significant improvement effect on mechanical displacement, and furthermore, a composition containing less than 0.005% of the subcomponent M n O showed a significant improvement effect on hysteresis. Therefore, it was excluded from the scope of the present invention.

[Example] Hereinafter, examples of the present invention will be described in detail while comparing with reference examples.

As starting materials, pbO, Ni with chemical purity of 99% or more
p, Nb205. Sb20. ', ZrO2°TiO2, and predetermined subcomponents were selected and precisely weighed to give the compositions shown in Tables 1 to 6. Next, these raw materials were mixed in a ball mill, dried, and pre-fired at 850'C. Next, an appropriate amount of an organic binder was added to the powder obtained by pulverization using a ball mill, and the mixture was granulated, followed by pressure molding at a pressure of 1 ton/c-.

It was baked at a temperature of 1200-1250°C for several hours.

The obtained sintered body was cut into a predetermined shape and polished, and then electrodes were attached and polarization was performed by applying a DC electric field of 35 to 50 kv/cI for 30 minutes in silicone oil at a temperature of 60 to 100°C. was applied to piezoelectrically activate it. next,
After determining the number of piezoelectric chambers using a predetermined measurement method, polishing was performed to confirm the actual effect, and two types of rectangular piezoelectric elements were obtained: Thickness: 1mm, length: 35mm, width: 10mm, thickness: 0.
15++n was obtained. Of these two types of piezoelectric elements, the shape■
to those of.

A DC voltage of 500 V was applied in the same direction as the polarization direction.

The electrostriction fl (shrinkage strain) that occurs at that time is measured.

617M (6 g...shrinkage 1 g...element length), the piezoelectric element with one side shape ■ was further sandwiched between both sides on a metal elastic plate and subjected to bimorph type displacement as shown in Fig. 2. Mechanical displacement and hysteresis were investigated.

As shown in Figure 1, mechanical displacement is determined by the displacement ds3o that occurs at the tip when one end is fixed and the other end is free when a DC voltage of 30V is applied, while hysteresis is determined by applying a DC voltage of 30V.
It was calculated from the following equation from the displacement dS at V and the residual displacement dSo generated when the voltage was returned to zero.

Hysteresis-a(dSo/dSso)X
100 C%] Examples of the results are shown in Tables 1 to 6.

In Tables 1 to 6, the sample numbers marked with * correspond to the piezoelectric ceramic compositions of the present invention. As is clear from Table 1, the samples made of the piezoelectric ceramic composition of the present invention have a large amount of electrical strain and mechanical displacement, and have extremely high voltage-displacement hysteresis compared to the reference examples of each composition group. small,
It is clear that H has favorable characteristics as a displacement element.

2. In the embodiments of the present invention, the electrical strain amount 1 mechanical displacement and voltage-displacement hysteresis accompanying the piezoelectric transverse effect have been explained with particular reference to the bimorph type piezoelectric displacement element. The longitudinal effect has also been investigated and its improvement effect has been confirmed, so it is fully possible to apply it to, for example, a laminated piezoelectric displacement element.

〔Effect of the invention〕

In this way, one aspect of the present invention is as follows.

P b [(N i l, Nb2.)A-(Sb+□N
b+ 2) a Z r (TiD) 03 is the basic composition, A, B, C, and D are each set in appropriate ranges, and L a 2031Co20. and M n O are simultaneously added as by-products in appropriate ranges. In particular, due to the interaction between the PB(Sb, □Nbr, 2)03 component in the basic composition and the subcomponents, a larger electrostriction than 1 which could not be achieved with conventional compositions is achieved. Low hysteresis can be achieved with quantity 2 mechanical displacement.

Furthermore, the piezoelectric ceramic composition of the present invention can be expected to be applied to the following uses.

(1) Since large mechanical displacement is generated and voltage/displacement hysteresis is small, it can be widely applied to new fields of displacement elements that require high-precision position control.

(2) Since it generates a large mechanical displacement, it can be made smaller, lighter, and driven at a lower voltage, and can be applied to the field of displacement elements that meet the energy saving era.

(3) Application to displacement elements requiring large mechanical displacement at relatively low voltage is possible.

(4) By adopting a one-sided drive method (applying only a DC voltage in the same direction as the polarization direction of the piezoelectric element), it can be applied to displacement elements that require large mechanical displacements.

In this case, the magnitude of the applied voltage can be freely selected depending on the application.

(5) Since it has a relatively high piezoelectric constant (for example, piezoelectric d constant), it can be applied to various piezoelectric products that require a high piezoelectric constant.

As detailed above, the piezoelectric ceramic composition of the present invention is suitable for displacement elements that can be used in a wide range of applications, and is of great industrial value.

[Brief explanation of drawings]

FIG. 1 is a graph showing a measurement standard in an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a conventional bimorph type piezoelectric displacement element. In the figure, 1 is a metal elastic plate, and 2.2' is a piezoelectric ceramic plate.

Claims (1)

[Claims] 1. General formula Pb[(Ni_1_/_3Nb_2_/_3
)_A(Sb_1_/_2Nb_1_/_2)_BZr
_CTi_D]O_3 (where A+B+C+D=1) satisfies 0.300≦A≦0.550 0.002≦B≦0.050 0.120≦C≦0.290 0.280≦D≦0.408 For the basic composition, La_2O_3 is 0.01
A piezoelectric ceramic composition characterized in that it contains Co_2O_3 in an amount of 0.01 to 0.3% by weight, and MnO in an amount of 0.005 to 0.15% by weight.