Hierarchical domains in Na1/2Bi1/2TiO3 single crystals: Ferroelectric phase transformations within the geometrical restrictions of a ferroelastic inheritance

We have found unique hierarchical domains in Na1/2Bi1/2TiO3 single crystals. A tetragonal ferroelastic domain structure is unchanged on cooling from 520 to 25 °C. Polar microdomains then nucleated on cooling in the rhombohedral ferroelectric phase within the geometrical restrictions imposed by the inherited ferroelastic domains.