High temperature piezoelectric ceramics in the Bi(Mg1/2Ti1/2)O3-BiFeO3-BiScO3-PbTiO3 system

Compositons in the pseudoquaternary system, 1-×(0.35Bi(Mg1/2Ti1/2)O3-0.30BiFeO3-0.35BiScO3)—×PbTiO3 were fabricated and characterised at the morphotropic phase boundary (MPB) between ferroelectric rhombohedral and tetragonal phases. The MPB occurred at × ≈ 0.48 at which composition the ferreoelectric to paraelectric phase transition, TC = 450°C, the piezoelectric constant, d33 = 328 pC/N and electromechanical coupling factor, kp = 0.44. The piezoelectric properties are viable for actuator applications but lower than equivalent high TC piezoelectrics such as 0.36BiScO3–0.64PbTiO3 (d33 = 450 pC/N, TC = 450°C). However, the relative reduction in the Sc2O3 content gives a significant cost saving which may prove a commercial advantage.