JPH07206519A - Piezoelectric ceramic - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric ceramic having improved strength by using a composition expressed by a specific formula as a main component and adding a specific amount of WO3 as a subsidiary component. CONSTITUTION:This piezoelectric ceramic having high strength is produced by weighing main components consisting of PbO, TiO2, ZrO2, Zn0, Nb2O3, MnO2, Al2O3 and SiO3 at ratios to give a composition expressed by formula (A+B+C=1; 0.05<A<0.25; 0.38<B<0.59; 0.29<C<0.50; 0.1<alpha<2.0; 0.1< beta<2.0; 0.01<gamma< 0.2), adding 0.1-2.0wt.% (based on the main component) of O3 as a subsidiary component, calcining the mixture after mixing, drying and crushing, pulverizing the calcined product, granulating by adding a binder such as PVA, pressing to a prescribed form, stacking the press-formed materials one upon another interposing a chemically inert ZrO2 powder treated at high temperature between the formed materials to prevent the fusion of the materials, baking the stacked material, shaping the sintered material in the form of a circular dusk, applying an Ag paste to both faces of the disk, baking the paste to form electrodes and applying electric current to effect the polarization of the disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric ceramic.

[0002]

2. Description of the Related Art Conventionally, piezoelectric ceramics have been used for oscillators and filters of TVs and communication devices, and have been manufactured at high temperature and high pressure using a material of high purity and fine powder particles.

[0003]

The conventional piezoelectric ceramic has the problems that its electrical characteristics change due to its densification, and its strength decreases and cracks occur in the element when it is downsized. It was

Therefore, the present invention has an object to improve the strength of the piezoelectric ceramic without changing the electrical characteristics.

[0005]

To achieve this object, the piezoelectric ceramic of the present invention contains 0.1 to 2.0% by weight of WO ₃ in the main component represented by (Chemical formula 2). Form with things.

[0006]

[Chemical 2]

[0007]

[Action] WO ₃ a by adding 0.1 to 2.0 wt%, WO ₃ is precipitated in the grain boundary layer of the piezoelectric ceramic, inhibiting the growth of crystals. As a result, the crystal can be densified without changing the electrical characteristics and a piezoelectric ceramic with improved strength can be obtained.

[0008]

EXAMPLES An example of the present invention will be described below.

First, PbO, TiO ₂ , ZrO ₂ , Zn
A predetermined amount of O, Nb ₂ O ₅ , SiO ₂ , and WO ₃ was weighed so as to have the composition shown in (Table 1), pure water was added using a ball mill, and they were mixed for about 24 hours.

[0010]

[Table 1]

Next, the dried and crushed pieces were placed in an alumina crucible, calcined at 850 ° C. for 2 hours, placed again in a ball mill, added with pure water, pulverized for 24 hours, and then dried. Then, add 6% polyvinyl alcohol as a binder in a mortar, granulate using a pestle, and then uniformly fill the mold, and mold at a pressure of about 1 ton / cm ² to a diameter of 20 mm and a thickness of about 2 mm. did.

Next, in order to prevent reaction fusion between the compacts, ten zirconium oxide powders which were chemically inactive and subjected to high temperature treatment were laid between the compacts and stacked, and then fired in an alumina jar. . After that, the obtained sintered body has a diameter of 16 m.
After processing to a thickness of 1.0 mm and a thickness of 1.0 mm, silver paste was applied on both sides and baked to form electrodes, and then a direct current was applied in silicon oil for polarization.

Next, the electrical characteristics of the piezoelectric ceramic provided with these electrodes were measured, and the porcelain density (ρ g / cm ³ ) and dielectric constant (ε ₃₃
^T / ε ₀ ) and electromechanical coupling coefficient were determined and are shown in (Table 1).

Further, the silver electrode on the surface is removed, and the length becomes 5.1.
The bending strength (kgf / cm ² ) of the piezoelectric ceramic processed into mm, width 1.8 mm and thickness 0.45 mm was measured and shown in (Table 1).

Looking at (Table 1), sample Nos. 2 to 5 and 8 to
The content of WO ₃ is 0.1 to 11, 14 to 17
It can be seen that when the content is 2.0% by weight, the strength is improved without impairing the electrical characteristics. On the other hand, sample No. 1, 7, 1
When the content of WO ₃ is less than 0.1% by weight as shown in No. ₃ , the strength is hardly improved, and when the content of WO ₃ exceeds 2.0% by weight like Sample Nos. 6, 12, and 18. , The strength and the electrical characteristics are significantly deteriorated.

[0016]

As described above, according to the present invention, a piezoelectric ceramic with improved strength can be obtained without impairing the electrical characteristics.

Claims (1)

[Claims] 1. A piezoelectric ceramic in which 0.1 to 2.0% by weight of WO ₃ is contained as a subcomponent in the main component represented by the formula (1). [Chemical 1]