Effect of thickness-mediated misfit strain on the heterophase polydomain structure of epitaxial BiFeO3 films

A heterophase polydomain structure capable of providing large electromechanical responses was recently discovered in BiFeO3 epitaxial ferroelectric films. In this work, the energetics of such a microstructure are analyzed to predict the equilibrium volume fraction of domains at different film–substrate lattice misfits, which is a function of the substrate lattice parameters as well as the film thickness. The results from this work provide a theoretical starting point for designing and engineering elastic polydomains in BiFeO3 thin film materials.