Theory and mechanisms for martensitic transformations in ferroelectrics. Part I. proper transitions

Abstract

A quasi-one-dimensional (QOD) model in which soft modes develop by fluctuating correlated ionic shifts is applied to proper ferroelectric transitions, including cubic→ tetragonal, tetragonal→orthorhombic, and orthorhombic→orthorhombic, where the structural change is accomplished by two lattice-variant shears and a volume change relaxation.