A planar complex phase interface in BaTiO3

A model is proposed for a complex phase interface separating the cubic and tetragonal phases in barium titanate, which consists of an intermediate layer of the induced phase with small monoclinic distortions near the interface. It is demonstrated that the induced phase can have two different structures, which are formed during the direct and reverse phase transitions, respectively. The parameters of these structures, equations of phase boundaries, relative orientations of the phases upon the phase transition, and the number of possible orientation states are determined.