Ferroelectric domain structure of SrBi2Nb2O9 epitaxial thin films.

The domain structure in a ferroelectric with well-defined crystallography and negligible ferroelastic distortion (<0.002%) is reported. In contrast to prototypical ferroelectrics in which long-range elastic strain dictates the domain structure, in SrBi2Nb2O9 the elastic term is insignificant, allowing dipole-dipole interactions and domain wall energies to dominate in determining the domain structure. Electron microscopy reveals ferroelectric domains that are irregularly shaped and highly curved. Out-of-phase boundary defects are shown to be weakly correlated with 90 degrees ferroelectric domain structure.