JPH10303476A - Polarizing method of piezoelectric member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize excellent polarization state without damaging electrodes, by stacking a plurality of piezoelectric members wherein electrodes are formed on both surfaces, via conducting members. SOLUTION: Electrodes 12 are formed on the upper surfaces of piezoelectric members 11, and electrodes 13 are formed on the lower surfaces of the piezoelectric members 11. The piezoelectric members 11 are stacked via stick-shaped conducting members 14, and a power supply 15 is connected with the electrode 12 of the uppermost step and the electrode 13 of the lowermost step. When a member such as an Au wire whose section is circular is used for the stick-shaped conducting member 14, contact parts with the electrode 12 and the electrode 13 are not surfaces but lines, so that contact irregularity is reduced and stability is obtained. When the same material as the outermost surfaces of the electrodes 12 and 13 is used for the stick-shaped conducting member 14, the stick-shaped conducting member 14 and the electrodes 12 and 13 are not damaged. In gas, electric field is applied across the electrodes of the outermost parts of the piezoelectric members stacked in this state, and polarizing is performed. The electrodes are not directly in contact with each other, but in contact with the conducting members, so that contact irregularity is reduced and heat is hardly generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polarizing a piezoelectric material used in various piezoelectric devices such as a piezoelectric oscillator and a piezoelectric filter.

[0002]

2. Description of the Related Art Conventionally, when a piezoelectric material such as a piezoelectric ceramic is polarized, a piezoelectric material 11 having electrodes 12 and 13 formed on both surfaces thereof in a gas such as a highly insulating gas as shown in FIG.
Are connected to the power supply 15 in a state of being directly superposed, and an electric field is applied to perform polarization.

[0003]

In the above method, the electrode 12 and the electrode 13 provided on the piezoelectric body 11 are superimposed so as to be in direct contact with each other. , Resulting in unstable contact. For this reason,
In particular, in the polarization of the piezoelectric body 11 having a low resistance value or the polarization at a high temperature at which the resistance value of the piezoelectric body 11 decreases, a current easily flows at the time of polarization. There has been a problem that the electrodes 12 and 13 are damaged by fusing together.

Accordingly, an object of the present invention is to provide a piezoelectric body having a good polarization state without damaging the electrodes, regardless of the type of the piezoelectric body or the temperature of polarization.

[0005]

In order to achieve this object, a method for polarizing a piezoelectric body according to the present invention comprises a first step of laminating a plurality of piezoelectric bodies provided with electrodes on both sides via a conductor. A second step of applying an electric field in a gas between the outermost electrodes of the next superposed piezoelectric body to polarize them, wherein the electrodes are not in direct contact with each other, Since the contact is with the conductor, contact unevenness is reduced, and heat is hardly generated. Further, even if heat is generated, the space between the piezoelectric bodies has a space between the piezoelectric bodies, so that the heat dissipation is good and the above object can be achieved.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The first aspect of the present invention is a first step of superposing a plurality of piezoelectric bodies provided with electrodes on both sides via conductors, and a step of superimposing the piezoelectric bodies. To polarize by applying an electric field in the gas between the outermost electrodes of
And a method of polarizing a piezoelectric body, comprising the steps of: (a) providing a piezoelectric body having a favorable polarization state efficiently without damaging an electrode provided on the piezoelectric body;

A second aspect of the present invention is a method of polarizing a piezoelectric body using a conductor having a linear contact portion between the electrode provided on the piezoelectric body and the conductor. Contact unevenness can be further reduced.

According to a third aspect of the present invention, as the conductor,
This is a method of polarizing a piezoelectric body using at least one metal selected from gold, silver, and platinum, and can prevent deterioration of a conductor even at high temperatures.

According to a fourth aspect of the present invention, as the conductor,
This is a method for polarizing a piezoelectric body using the same substance as the substance on the outermost surface of an electrode provided on the piezoelectric body, and can prevent reaction and diffusion between the conductor and the electrode provided on the piezoelectric body.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a cross-sectional view showing a polarization method according to the present embodiment. An electrode 12 is provided on an upper surface of a piezoelectric body 11, an electrode 13 is provided on a lower surface, and a rod-shaped conductor 14 is provided. The power supply 15 is connected to the uppermost electrode 12 and the lowermost electrode 13.

First, a piezoelectric ceramic containing lead zirconate titanate as a main component is cut into a square plate having a side of about 30 mm and a thickness of about 0.5 mm. 11 were produced. Electrodes 12 and 13 were provided on both surfaces of the piezoelectric body 11 using a vacuum evaporation machine so that the base was composed of Cr and the surface was composed of Au. Next, these were superposed via two bar-shaped conductors 14 each made of Au wire having a diameter of about 1 mm and a length of about 30 mm so that the three piezoelectric bodies 11 were electrically connected in series. . As described above, when a rod-shaped conductor having a circular cross-section, such as an Au wire, is used, the contact portions with the electrodes 12 and 13 are contacted not with the surface but with the line, so that the contact unevenness is further reduced and the contact is stabilized. . Further, when a metal having high corrosion resistance such as Au is used for the rod-shaped conductor 14, the conductivity is not impaired even in an oxidizing atmosphere. The rod-shaped conductor 14
When the same material as the outermost surfaces of the electrodes 12 and 13 is used, the electrodes 12 and 13 are not damaged by the reaction or diffusion between the rod-shaped conductor 14 and the electrodes 12 and 13.

Next, the uppermost electrode 12 and the lowermost electrode 1
The power supply 15 was connected to 3 and a DC voltage of 4.5 kV was applied to perform polarization.

Thereafter, the piezoelectric body 11 was cut at intervals of about 5 mm to form a rectangular plate having a length of about 30 mm, a width of about 5 mm, and a thickness of about 0.5 mm. The electromechanical coupling coefficient (k ₃₁ ) of the resonator thus obtained was measured. The results are shown in (Table 1).

[0014]

[Table 1]

As is clear from Table 1, the resonator using the polarization method of the present embodiment is not inferior to the conventional resonator and has a good polarization state. I understand.

In this embodiment, the piezoelectric body 1
Although a piezoelectric ceramic containing lead zirconate titanate as a main component is used as the material 1, similar effects can be obtained with other piezoelectric ceramics or piezoelectric single crystals.
The number of the piezoelectric bodies 11 is not limited to three. The number of the piezoelectric bodies 11 may be changed according to the capability of the power supply, or a plurality of superposed ones may be prepared and connected to the power supply in parallel.

Further, although a wire having a circular cross section is used for the rod-shaped conductor 14, it is not limited to a circular shape.
It is preferable to use one having a shape such that the contact portion with the electrodes 12 and 13 is not a surface but a line. In addition, the number of the piezoelectric bodies 11 was also used two each for stabilizing the piezoelectric bodies 11,
For example, the same effect can be obtained even if one bent sheet is used.

Further, the outermost surfaces of the electrodes 12 and 13 are made of Au.
However, it is preferable that the material is not easily affected by a noble metal such as Ag or Pt or the surrounding atmosphere, and the material of the rod-shaped conductor 14 may be changed accordingly.

Further, when the polarization is performed, when the applied voltage is high, it is preferable to perform the polarization in an insulating gas such as SF ₆ gas.

When polarization is performed in an atmosphere in which dielectric breakdown easily occurs, such as in air, the electrodes 12 and 13 are formed so as not to reach the ends of the piezoelectric body 11 in order to prevent dielectric breakdown. It is desirable.

[0021]

As described above, according to the present invention, the electrodes are not in direct contact with each other at the time of polarization, but are in contact with the conductors. Therefore, contact unevenness is reduced, and heat is hardly generated. Further, even if heat is generated, heat dissipation is good because there is air between the piezoelectric bodies.

Therefore, regardless of the type of the piezoelectric material and the temperature of the polarization, it is possible to efficiently obtain a piezoelectric material having a good polarization state without damage to the electrodes.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a polarization state according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional method of polarizing a piezoelectric body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Piezoelectric body 12 Electrode 13 Electrode 14 Rod conductor 15 Power supply

Claims (4)

[Claims] 1. A first step of superposing a plurality of piezoelectric bodies provided with electrodes on both sides via a conductor, and then applying an electric field between the outermost electrodes of the superposed piezoelectric bodies in a gas. And a second step of polarizing the piezoelectric body. 2. The method for polarizing a piezoelectric body according to claim 1, wherein a contact portion between the electrode provided on the piezoelectric body and the conductor uses a conductor having a linear shape. 3. The method according to claim 1, wherein at least one metal selected from gold, silver, and platinum is used as the conductor. 4. The method for polarizing a piezoelectric body according to claim 1, wherein the same substance as the outermost material of the electrode provided on the piezoelectric body is used as the conductor.