Phase transformation characteristics of barium strontium titanate films on anisotropic substrates with (001)//(001) epitaxy

The role of anisotropic misfit strains on the spontaneous polarization of (100) oriented Ba0.6Sr0.4TiO3 thin films on (100) orthorhombic substrates is theoretically analyzed. A modified thermodynamic model is utilized to evaluate the equilibrium polarization values as a function of the anisotropic misfit strains. Results show that ferroelectric phases that cannot be observed in single-crystal Ba0.6Sr0.4TiO3 can be stabilized due to the reduction in the symmetry induced by the anisotropic strain state.