Effect of electric field and temperature on average structure and domain wall motion in 0.93Bi_0.5Na_0.5TiO₃-0. 07BaTiO₃ ceramic

In situ neutron powder diffraction patterns and dielectric spectra of 0.93Bi_0.5Na_0.5TiO₃-0.07BaTiO₃ ceramic were investigated under different electrical fields and temperatures. An electric-field-induced phase transition from metrically cubic to metrically tetragonal, associated with strong domain wall motion, occurs. Such induced phase and domain wall motion are unchanged until the high-temperature phase transition occurs from metrically tetragonal to metrically cubic. All these changes are irrelevant to the observed depolarization temperature (75°C). The depolarization behaviour is thus suggested to be associated with the local structure caused by the octahedral tilt twinning disorder.