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/sub C/), are Pb(Zr,TiO)/sub 3/ (PZT), PbTiO/sub 3/, (Pb,Ba)Nb/sub 2/O/sub 6/, Na/sub 0.5/Bi/sub 4.5/Ti/sub 4/O/sub 15/, and LiNbO/sub 3/. The maximum operation temperature is limited by T/sub C/ and dielectric loss combined with the level of electrical resistivity. With increased T/sub C/ also comes the expense of reduced piezoelectric coefficient (d), being further reduced in non-morphotropic phase boundary (MPB) systems. Recently new high T/sub C/ systems with MPBs analogous to PZT have been developed. Predicted by a perovskite crystal structure tolerance factor relationship, compositions based on Bi(Me)O/sub 3/-PbTiO/sub 3/, where Me=Sc/sup +3/,(Mg/sup +2/,Ti/sup +4/), etc., exhibit piezoelectric activity compared to PZT, with T/sub C/s greater than 100/spl deg/C higher, making them promising candidates for high temperature applications.