JPS6046556B2 - Manufacturing method of piezoelectric ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a piezoelectric ceramic material,
An energy confinement resonator for thick vertical vibrations can be constructed, and the mechanical quality factor QM and electromechanical coupling coefficient are...

The present invention provides a piezoelectric ceramic material having a large size and suitable for use in high frequency resonators, etc., which can be processed into a thin plate.

As the use of ICs in high-frequency circuits such as television receivers progresses, there is a strong demand for peripheral components of IC circuits, especially reactance circuits, to be solid-state, non-adjustable, and high-performance.

Piezoelectric ceramic resonators are expected to be able to meet this demand. When using a piezoelectric ceramic as a high-frequency resonator, it is advantageous to use thickness vibration, particularly thickness vertical vibration, in which the resonant frequency is determined by the thickness. The frequency constant of thickness vibration is about 2000H2-m, so if 50M
In order to obtain the resonant frequency of H2, the magnetic resonator must be processed into a very thin plate with a thickness of about 40 μm. Furthermore, when using thick vertical vibration in a resonator or filter, it is important to remove unnecessary resonance. The energy confinement method is effective for removing unnecessary vibrations.
The conditions under which this energy confinement method can be applied to the fundamental wave resonance of thick vertical vibration are (2-Cg.・S fan.)
It is necessary that Poisson's ratio σ given by /(2-2C83·S〒,) is larger than 113. However, the elastic stiffness related to the vertical vibration, S, is the elastic compliance related to the vertical vibration. Further, in order to obtain a resonator with low loss in a high frequency region, it is necessary that the mechanical quality factor QM is 20 degrees or more. Conventional firing methods yield only mechanically weak materials and can only be polished to a thickness of approximately 200 μm, making it difficult to obtain resonators of approximately 10 MH2 or higher even by thickness vibration. .

Furthermore, until now there have been very few examples of measurement of σ, and the composition range with σ of 113 or more has not been clarified.

Until now, no material has been obtained that has a QM of about 26 or more, a σ of 113 or more, and can be processed into a thin plate of 200 μm or less. The present invention has a σ of 113 or more and a σ of 20
It concerns a method of obtaining a piezoelectric ceramic material for high frequencies with a large coupling coefficient that can be processed into a thin plate of about 30 μm, including the QM on the zero view, and (1-w) (Pb
Til-z-ZrZO3)+WMnO2 (however, 0.
48≦z≦0.64, 0.004≦w≦0.06, Pb
Sr, Ca, Ba
The present invention is based on the discovery that it can be obtained by heating and pressurizing sintering under limited conditions.
Examples will be described below. PbO, SrCO3,
CaCO3, BaCO3, TiO2, zrO2, MnO
The raw materials No. 2 were weighed to have the composition shown in the table below, and wet mixed in a ball mill for 17 hours.

After the slurry was filtered and dried, it was calcined at about 850° C. for 2 hours, and then wet-pulverized again using a ball mill. After drying the crushed material, diameter 30TIrm1 thickness 17
A circular disk was molded at a pressure of 500 kg/d, and it was sintered under heat and pressure under the conditions shown in the table below. Thereafter, annealing treatment was performed at 900° C. for 4 hours. For comparison, a powder made under the same conditions was molded and fired normally. Cut out a disk with a diameter of 6w0n from these fired samples, and cut it into a size of at least 30μm.
It was polished to a thickness of . 30μ for mechanically weak samples
The thin plate element cracked by the time the thickness reached m, making it impossible to obtain the desired thin plate element. Note that the piezoelectric properties are good at a thickness of 0.
A gold electrode was provided on a 3-ring disk sample, and it was heated to 5KV/? in silicone oil at 160°C. Measurements were made on a sample to which a DC electric field of . K33 is 5×1×1, TrOOL
Measurements were made using a rod-shaped sample with dimensions of 3. Table 1 shows the relationship between firing conditions and polishing limits.

In normal firing, porcelain with maximum density can be obtained under the firing conditions shown in the table, but it was not possible to polish the porcelain to a thickness of 200 μm or less. However, according to the heat and pressure sintering of the present invention, an extremely thin ceramic body can be obtained. 30μm when the temperature of heating and pressure sintering is 1050 to 1300℃
I was able to polish it up to. Pressure force during sintering is 100k
If it is smaller than g/d, sintering is insufficient! This results in a non-uniform sample.
It was difficult to polish porcelain to a thickness of 200 μm or less. Porcelain that can be polished to a thickness of 30 μm was obtained by heat-pressing sintering at a pressure in the range of 100 to 500 k9/CTl. Regarding heating time, 0. If the sintering time is shorter than that, the sintering will be non-uniform, and a material that can withstand polishing into a thin plate of 100 μm or less cannot be obtained. Also, 2
Sintering at a depth greater than 100 degrees is undesirable because it significantly reduces the strength of the porcelain and the productivity. Therefore, the range of conditions for heating and pressure sintering in the method of the present invention is a temperature of 1050°C.
~1300℃, pressure 100~500k9/C! The range is between 0.5 and 2 for 11 hours. Table 1 shows a part of Pb
There is a table showing the polishing limit of compositions substituted with r, but P
Similar results were obtained with a composition in which part of b was replaced with Ba or Ca.

FIG. 1 shows the change in σ with respect to z for a ceramic sample (w=0.00 & composition in which atomic percent of Pb was replaced with Sr) heated and baked under the conditions of 1250° C. and 200 kg/Cltl for 4 hours.

As is clear from FIG. 1, σ was maximum when the value of z was 0.55. In this case, Kt and K33 are each 0
．． 55 and 0.70 showed large values. The tendency of the change in σ due to the change in z does not change much depending on the value of w, the type of element to be substituted (Sr, Ba or Ca), and the heating and pressurizing conditions. The range that satisfies the energy confinement condition of the fundamental wave of the thickness vertical vibration, that is, the condition of σ>113, is w=0.008, and for a composition in which 5 at.% of Pb is replaced with Sr, 0.48≦z≦0. 64 composition range.
Note that the condition of σ>113 was satisfied within the above range of z also in the case where w was 0.004 to 0.06 and the substituent element for Pb was Ba or Ca. Figure 2 shows temperature 12
The change in QM due to w of a sample (z=0.60, composition in which 10 atomic % of Pb was replaced with ?) which was heated and pressure sintered at 50° C. and a pressure of 200 kg/Clt for 4 hours is shown.

QM is maximum when w is 0.02. This tendency is
value, type of substituting element for Pb (Sr, Ba, or Ca
) and may vary depending on the heating and pressure sintering conditions. According to Figure 2, the range of w where QM is 200 or more is 0.00.
4 to 0.06. In addition, Sr of Pb,? or Ca
In compositions in which substitution exceeds 10 at.%, the decrease in Kt is significant, so the substitution is limited to 10 at.% or less.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the relationship between the composition and Poisson's ratio σ of a sample made by the method according to the present invention, and FIG. 2 is a diagram showing an example of the relationship between the composition and the mechanical quality factor QM. be.

Claims (1)

[Claims] 1 (1-w) [PbTi_1_-_zZr_zO_3+
In the composition represented by wMnO_2, 0.48≦z
Composition within the range of ≦0.64, 0.004≦w≦0.006 (however, 0 to 10 at% of Pb (0 is excluded)
is replaced with one or more of Sr, Ca, and Ba) is heated and pressure sintered at a temperature of 1050 to 1300°C and a pressure of 100 to 500 kg/cm^2 for 0.5 to 24 hours. A method for manufacturing piezoelectric ceramics.