Thinckness dependence of phase transition temperature of epitaxial ferroelectric films

Considering the electromechanical coupling boundary conditions, such as misfit strain in epitaxial ferroelectric thin films, surface eigenstrain relaxation and depolarization induced by surface charges, the phase transition temperature of epitaxial ferroelectric thin film is analyzed and discussed systematically via the dynamic Ginzburg-Landau equation (DGL). Linear stability analysis of the evolutionary trajectory of the system for the phase transition is adopted in this paper. Explicit expressions are then derived for the critical phase transition temperature under various electromechanical surface conditions. The important factors on phase transition temperature of ferroelectric films are discussed and compared with experimental data for BaTiO₃ thin film epitaxially grown on SrTiO₃ substrate.