Twin boundaries in perovskite

Abstract

The twin behaviour of natural and synthetic perovskite (CaTiO3) was examined by high-resolution electron microscopy (HREM) and selected-area electron diffraction (SAD). Pseudosymmetric twinning yields domains related to each other by either a 180 ° or a 90 ° rotation about an axis perpendicular to { 101}. A third type of twin involving a 180 ° rotation about the normal to ( 121 ) had previously been reported but this was not observed in the present study. The boundaries between twin domains were often complex and consisted of intergrowths on the finest possible scale of the various composition planes. It was confirmed that the most common composition planes were {101}; however, interface surfaces on {010} and {121} were also observed. For the simpler twin boundaries structural models were proposed and described using the Glazer notation.