On the Temperature Regions of the Phases of BaTiO3

Abstract

The Landau potential of BaTiO3 should be the invariant of the operations of the group Oh. By using the phase stability conditions, the temperature regions of possible phases are given. The pressure-temperature phase diagram of BaTiO3 has been investigated by using a modification of Landau potential. At low temperature, each phase boundary bends sharply down, and the non-linear behavior is associated with quantum effects. Saturation temperature characterizes the extent of quantum mechanical, and is related to the extent to which changes in the hard phonon modes influence the transition mechanism.