Roles of the Higher Order Anisotropic Terms in Successive Structural Phase Transitions: The Method of Determination of Phenomenological Parameters

Abstract

A simple and general method for choosing appropriate coefficients of the higher order invariants in the free energy function to reproduce successive phase transitions is presented. It is found, when applied to perovskite structure-based systems, that the phase sequences such as cubic-rhombohedral-orthorhombic-tetragonal, cubic-tetragonal-rhombohedral, cubic-rhombohedral-orthorhombic and cubic-rhombohedral-tetragonal are reproducible in the phase diagram as a result of appropriate choice of model parameters as shown using the present method.