Variation in phase diagrams of strained (011) epitaxial BaTiO3 thin films

Phenomenological theory based on sixth-order and eighth-order potentials are used to investigate the effect of variation in free energy coefficients and material constants on phase stability of single-domain (011)-oriented epitaxial BaTiO3 subject to both biaxial and uniaxial substrate constraints. Relative size of a variety of ferroelectric regions in the computed misfit strain phase diagrams is systematically examined. The computed Curie phase transition and subsequent polarization rotation and formation of low-symmetry monoclinic structures are dependent on the selection of potentials and variation in electrostrictive and elastic constants, and such dependence is found to be closely associated with in-plane strain anisotropy.