The phase diagram of epitaxial BaTiO3 films under bi-axial stress

The phase diagram of eptaxial BaTiO3 films in the coordinates of T and alpha(s) (substrate thermal expansion coefficient) is constructed on the basis of the thermodynamic analysis which has been carried out earlier [1]. It is found that two new phase are formed under bi-axial stress. The temperature dependencies of polarization and unit cell parameters for the films on the KTaO3 and SrTiO3 substrates are also calculated.