Nanoscale oxygen octahedral tilting in 0.90(Bi1/2Na1/2)TiO3–0.05(Bi1/2K1/2)TiO3–0.05BaTiO3 lead-free perovskite piezoelectric ceramics

The oxygen octahedral tilted domains in 0.90(Bi1/2Na1/2)TiO3–0.5(Bi1/2K1/2)TiO3–0.5BaTiO3 lead-free perovskite piezoelectric ceramic have been studied by transmission electron microscopy (TEM). Selected-area electron diffraction patterns shows the 12ooo and 12ooe reflections, indicating the presence of antiphase (a−a−a−) and in-phase (aoaoc+) octahedral tilting, respectively. The morphology and distributions of these tilted domains are shown in the centered dark-field images. Further, the Bragg-filtered high-resolution TEM image reveals that the size of the in-phase tilted domains varies from 1 to 8 nm across. The ceramic contains the mixture of nontilted and variants of the antiphase and in-phase tilted domains.