A phenomenological Gibbs function for the single cell region of the PbZrO3:PbTiO3 solid solution system

Abstract

The ADAGE computer graphics system has been used to develop a modified Devonshire form for the elastic Gibbs function to describe the simple proper ferroelectric phases in the PbZrO3:PbTiO3 family of crystalline solid solutions. The unusual morphotropic phase boundary between tetragonal and rhombohedral forms has been used to help delineate the coefficients in the function at that composition. For the Devonshire formulation, spontaneous strain in the ferroelectric phases is assumed to be electrostrictive in origin and an x-ray determination of the strains as function of composition and temperature has been used to derive the composition and temperature dependence of the higher order stiffness coefficients. The Gibbs function which has been derived permits for the first time the calculation of the full family of thermal, elastic, dielectric, and piezoelectric parameters for the ferroelectric single domain states and an evaluation of the manner in which these parameters change under different elastic and electric boundary conditions.