A transmission electron microscopic investigation was made of the occurrence of various orientational states, and their relationship to rhombohedral distortions of the compound. It was shown that the twinned microstructure which was observed was consistent with that which was expected from group/sub-group relationships between the prototype and the room-temperature phase. Domain wall orientations were deduced from ferroelastic theory.

F.Sandiumenge, S.Gali, S.Piñol: Philosophical Magazine Letters, 1997, 76[1], 41-8