| 摘要 |
PROBLEM TO BE SOLVED: To obtain a piezoelectric porcelain compsn. fit for a wide band filter utilizing thickness glide mode resonance, capable of firing at a relatively low temp. and having such characteristics as a high relative dielectric constant and a high electromechanical coupling factor by substituting at least one among Ca, Sr and Ba for a specified percentage of Pb in a compd. consisting of Pb, Nb, Cr, Ti, Zr and O. SOLUTION: At least one among Ca, Sr and Ba is substd. for 5-20 mol.% of Pb in a compd. represented by the formula (1.00<=α<=1.06, 0.02<=A<=0.10, 0.40<=B<=0.65, 0.25<=C$<=0.58 and A+B+C=1) to obtain the objective piezoelectric porcelain compsn. A sintered compact of this compsn. is polarized by applying a DC electric field of >=3.5 kV/mm at 130-180 deg.C and it is heat-treated at a high temp. of 180-250 deg.C to obtain the objective piezoelectric porcelain having a high electromechanical coupling factor and satisfactory heat resistance and less liable to a change in resonance frequency and piezoelectric characteristics before and after a temp. cycle with the lapse of time. |
