High temperature piezoelectric ceramics

摘要

Piezoelectric ceramics that can be used in high temperature actuators. The piezoelectric ceramics have various desirable properties, for example the materials do not depole up to about 400° C. and have large piezoelectric coefficients >400 pm/V. In addition the thickness mode electromechanical coupling coefficient is large, increasing from 0.5 to 0.65 with temperature. The planar electromechanical coefficient is around 0.40 and does not show a significant dependence on temperature. These materials are highly polarizable with remnant polarization around 50 muC/cm2 and are electrically hard with coercive field above 20 kV/cm. They exhibit single crystal like ferroelectric behavior with square hysteresis loops. Such properties make these materials a piezoelectric ceramic that can be used in stack actuators at high temperatures. Methods for preparing the piezoelectric ceramics are also disclosed.