Piezoelectric Properties of Modified PbTiO₃ Ceramics

PbTiO 3 ceramics with high density and high resistivity have been prepared by adding less than 5 mol % of Bi 2/3 TiO 3 , PbZn 1/3 Nb 2/3 O 3 or their derivatives. These ceramics have dielectric constants of about 200, and can be poled at 200°C under a d. c. field of 40 to 70 kV/cm. The piezoelectric coupling factors k 15 , k 33 and k 31 amount to 0.43, 0.35 and 0.068, respectively. The value of k 33 is nearly constant up to the Curie temperature of about 500°C. The aging rate of frequency constant does not exceed 0.1%/time decade. The present ceramics can be used as stable piezoelectric elements in high temperature and high frequency.