High piezoelectricity associated with crossover from nonergodicity to ergodicity in modified Bi0.5Na0.5TiO3 relaxor ferroelectrics

The structural origin of high piezoelectricity in perovskite-type relaxor ferroelectrics is a fundamental issue that remains elusive for decades. In this study, high and unstable piezoelectricity for the poled ceramics, accompanied with a crossover from a nonergodic relaxor to an ergodic relaxor state at room temperature, has been observed for 0.95(Bi_0.5Na_0.5)_1-x (Li_0.5Sm_0.5) _x TiO₃–0.05BaTiO₃ ceramics with x = 0.06. The result suggests that the high piezoelectric activity origins from the electric field-induced-ordered nanodomains. The rapid loss of piezoelectricity stems from the reversibility of the ordered nanodomains after removing applied electric field.