New High Temperature Morphotropic Phase Boundary Piezoelectrics Based on Bi(Me)O₃–PbTiO₃ Ceramics

Abstract

New morphotropic phase boundary (MPB) piezoelectrics, with ferroelectric phase transition ( T c ) exceeding that of PbZrO 3 –PbTiO 3 (PZT), were investigated. Based on a perovskite tolerance factor- T c relationship, new high T c MPB systems were projected in the Bi(Me)O 3 –PbTiO 3 system, where Me is a relatively large B +3 -site cation. For the (1- x )BiScO 3 –( x )PbTiO 3 solid solution, a MPB was found at x -0.64 separating the rhombohedral and tetragonal phases, with correspondingly enhanced dielectric and piezoelectric properties. A transition temperature T c of ∼ 450°C was determined with evidence of T c 's on the order of ≥ 600°C in the BiInO 3 and BiYbO 3 analogues, though issues of perovskite stability remain for the smaller tolerance end-member systems.