Boundaries between coexisting phases in BaTiO3

The article presents a theoretical analysis of interphase boundaries between the coexisting phases at phase transitions in a perovskite ferroelectric. The concrete compound of BaTiO3 is chosen because of the most complete information on the values of the parameters of the Landau–Ginzburg–Devonshire phenomenological potential. The monoclinic phase has been observed in the temperature interval between the tetragonal and orthorhombic phases. The detailed analysis of the phase transition and the energy characteristics of the monoclinic phase in this temperature interval are studied using BaTiO3 as an example of a ferroelectric. The interphase boundaries between the tetragonal and orthorhombic phases and the monoclinic phase are investigated. The temperature dependencies of the width and surface energies of these boundaries are calculated and compared with domain walls within the different ferroelectric phases of BaTiO3.