High performance, high temperature perovskite piezoelectrics

The industrial and scientific communities have expressed the need for sensing and actuation over a broad temperature range. This review presents high temperature piezoelectric materials that are commercially available and those that are under development. Key materials, in order of increasing Curie temperature (T_C), are Pb(Zr,TiO)₃ (PZT), PbTiO₃, (Pb,Ba)Nb₂O₆, Na_0.5Bi_4.5Ti₄O₁₅, and LiNbO₃. The maximum operation temperature is limited by T_C and dielectric loss combined with the level of electrical resistivity. With increased T_C also comes the expense of reduced piezoelectric coefficient (d), being further reduced in non-morphotropic phase boundary (MPB) systems. Recently new high T_C systems with MPBs analogous to PZT have been developed. Predicted by a perovskite crystal structure tolerance factor relationship, compositions based on Bi(Me)O₃-PbTiO₃, where Me=Sc⁺³,(Mg⁺²,Ti⁺⁴), etc., exhibit piezoelectric activity compared to PZT, with T_Cs greater than 100°C higher, making them promising candidates for high temperature applications.