Preparation and Characterization of High Temperature Perovskite Ferroelectrics in the Solid-Solution (1-x)BiScO₃–xPbTiO₃

The dielectric and piezoelectric properties of the new perovskite solid solution system (1-x)BiScO₃–xPbTiO₃ were investigated. This system is representative of a new group of high temperature piezoelectrics that includes Bi(Me)O₃–PbTiO₃, where Me⁺³ is a relatively large cation, Sc, Y, Yb, In, etc., and combinations thereof. In the (1-x)BiScO₃–xPbTiO₃ series, perovskite stability was achieved for x>50 mol% PbTiO₃ being ferroelectric rhombohedral and transforming to ferroelectric tetragonal in the region x=64 mol% PbTiO₃, designated as the morphotropic phase boundary (MPB). Analogous to (1-x)PbZrO₃–xPbTiO₃ (PZT), the dielectric and piezoelectric properties were enhanced for compositions near the MPB. Piezoelectric coefficient d₃₃ values reached 450 pC/N, comparable to soft PZT's with a transition temperature of 450°C, more than 100°C higher than commercial PZT. The combination of high T_C and excellent piezoelectric activity make (1-x)BiScO₃–xPbTiO₃ materials candidates for high temperature, and temperature stable actuators and transducers.