Imaging planar tetragonal sheets in rhombohedral Na0.5Bi0.5TiO3 using transmission electron microscopy

Planar nanometre-scale inclusions in single-crystal Na0.5Bi0.5TiO3 have been investigated using transmission electron microscopy at room temperature. In diffraction patterns, they give rise to weak extra spots and diffuse contrast. Here we show that they are visible in diffraction contrast images, giving a new route to directly observe subtly different structures in perovskites. Visibility is determined by their structure and diffraction vector. We show that single-crystal a−a−a− Na0.5Bi0.5TiO3 contains an inhomogeneous distribution of nanometre-scale {0 0 1} platelets of tetragonal a0a0c+ material.