JPS5937594B2 - piezoelectric ceramic composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric ceramic composition, particularly a piezoelectric ceramic composition with excellent piezoelectric properties suitable for use in powerful ultrasonic vibrators, piezoelectric transformers, speakers, and the like.

Traditionally, piezoelectric ceramic materials include barium titanate porcelain, lead zirconate titanate porcelain, magnesium niobate titanate zirconate lead porcelain, and zinc niobium tin niobate titanate zirconoate lead porcelain, depending on the intended use. Various improvements have been made accordingly.

Although each of the above compositions has its own characteristics, it still has various drawbacks. That is, one of the problems is that in conventional compositions, the value of internal stress at which the piezoelectric properties begin to deteriorate is relatively small. The present invention eliminates the drawbacks of the conventional compositions described above and provides a piezoelectric ceramic composition with significantly superior properties.

That is, the piezoelectric magnetic composition of the present invention specifically includes P
b(Zn“Nb”)A(Sn,ANb゛)BTiCZr
D03 (however, 0<A≦0.50, 0<B≦0.25
, 0.25≦C≦0.625, 0.20≦D≦0.62
5, A + B + C + D = 1), and a composition in which 15% or less of the lead atoms are replaced with one or more of strontium, calcium, and barium as the basic composition, and 0.05 to 5% by weight of the total amount of manganese dioxide (MnO2) as a subcomponent,
and 0.05 to 2 of the total amount of cerium oxide (Ce02)
．． It is characterized by containing 5% by weight. As a result, it is possible to provide a piezoelectric ceramic composition having characteristics such as a large electromechanical coupling coefficient and a large mechanical quality factor, and excellent linearity of resonance frequency and resonance resistance with respect to internal stress. The characteristics that a piezoelectric material should have differ depending on its use.

For example, in applications such as vibrators for generating powerful ultrasonic waves and voltage transformers, the electromechanical coupling coefficient and mechanical quality factor are large compared to the piezoelectric ceramics that constitute them, and the resonant frequency and resonant resistance are also large. , excellent linearity with respect to internal stress is required. The present invention relates to a piezoelectric ceramic composition suitable for such uses. Hereinafter, the composition of the present invention will be explained in detail based on Examples. First, raw materials were weighed and mixed to have the composition shown in the following table.

This mixture was calcined at about 850° C. for 2 hours and then wet-pulverized in a ball mill. After drying the crushed material, approximately 70
A disk with dimensions of 20 ml in diameter and 2 I1 in thickness was molded at a pressure of 0 kg/cm and fired at a temperature in the range of 1200-1300° C. for about 45 minutes. To measure piezoelectricity, use fired porcelain about 1 meter thick! After polishing and baking silver electrodes on both sides, it was polarized in silicone oil at a temperature in the range of 100 to 150°C with a DC voltage of 3 to 4 KV/degree. In addition, the linearity of the resonant frequency with respect to internal stress was determined using the above disk sample with a length of approximately 12.5 m.
m, cut into a bar shape with a cross section of 2 x 2 m as a sample,
The horizontal effect of the bar was measured and evaluated. In addition, during the above process, M
Even when nO2 and CeO2 were added at the time of crushing the calcined product, they showed similar characteristics. In addition, as raw materials, PbO,
ZnO, SnO2, Nb2O5, TiO2, zrO2,
MnO2, ceO2, srcO3, cacO3, Bac
Although O, was used, other peroxides, hydroxides, carbonates, etc. can also be used. The following table shows the properties of the porcelain composition of the present invention.

In addition, A, B, C, and D in the table are Pb(Zn〆NZΔ)A
(Sn, 7-Nb back) This is the ratio of each component in the basic composition shown by BTiCZrDO3. Further, FR-T is a change in the resonance frequency when the maximum internal stress is 150 kg/CF7l with respect to the resonance frequency at the maximum internal stress number Kg/Cd. As is clear from the above table, the porcelain made of the composition of the present invention has the following properties: by adding MnO2 to the basic composition and further adding CeO2 to contain both,
The linearity of the resonant frequency with respect to internal stress is significantly improved without reducing the large coupling coefficient (Kp) and mechanical quality factor (QM) obtained by the basic composition and the inclusion of MnO2, and the maximum Internal stress is 150kg/
Changes in resonance frequency when using CrA are reduced.

Therefore, the composition of the present invention is useful for applications such as powerful ultrasonic vibrators and piezoelectric transformers. Further, it goes without saying that the same improvement effect can be obtained with compositions other than the above-mentioned examples within the scope of the present invention. In addition·
, A>0.50, B>0.25, C<0.25, C>0
．． 625, D<0.20, D>0.625 is difficult to sinter or has low piezoelectricity (Kp is 0.15 or less).
b(7) Compositions in which the amount of substitution by one or more of Sr, Ca, and Ba exceeds 15% have a significant decrease in piezoelectricity, and compositions in which the amount of MnO2 is less than 0.05% by weight has a small QM, and compositions exceeding 5% by weight are difficult to sinter, and the amount of VcceO2 is 0.05% by weight.
Compositions containing less than 2.5% by weight and more than 2.5% by weight have little effect on improving the linear range for internal stress at the resonance frequency.
Each range has been excluded from the present invention.

Claims (1)

[Claims] 1 Pb(Zn_1_/_3Nb_2_/_3)_A(
Sn_1_/_3Nb_2_/_3)_BTi_CZr
_DO_3 (However, 0<A≦0.50, 0<B≦0.
25, 0.25≦C≦0.625, 0.20≦D≦0.
625, A+B+C+D=1) as the basic composition, and manganese dioxide (Mn
A piezoelectric ceramic composition comprising 0.05 to 5% by weight of O_2) and 0.05 to 2.5% by weight of cerium oxide (CeO_2), respectively. 2 Pb(Zn_1_/_3Nb_2_/_3)_A(
Sn_1_/_3Nb_2_/_3)_BTi_CZr
_DO_3 (however, 0<A≦0.50, 0<B≦0.2
5, 0.25≦C≦0.625, 0.20≦D≦0.6
25, A+B+C+D=1), in which 15% or less of the lead atoms are replaced with one or more of strontium, calcium, and barium, and manganese dioxide (MnO_2) 0.05 to 5% by weight of the total amount, and cerium oxide (CeO
A piezoelectric ceramic composition comprising _2) in an amount of 0.5 to 2.5% by weight based on the total amount.