Electrostrictive effects in non-polar perovskites

Polarization-related electrostrictive coefficients Qh have been determined for relaxation dielectrics 0.856Sr TiO3-0.144 Bi2/3 TiO3 and (K3/4Bi1/4) (Zn1/6Nb5/6)O3, and for a simple non-polar perovskite BaZrO3 by measuring the hydrostatic pressure dependence of the dielectric permittivity. Anomalous variation in the electrostrictive coefficient with temperature and frequency were observed in (K3/4Bi1/4) (Zn1/6Nb5/6)O3 in the relaxation-temperature region. This behavior can be explained qualitatively with a simple model based on potential barriers separating alternative cation sites. The empirical rule noted previously for ferroelectric perovskites, that the electrostrictive Q coefficient increases with cation order from disordered, through simple and then ordered perovskites is confirmed again in non-polar perovskites.