A phenomenological constitutive law for the behaviour of ferroelectric ceramics

Abstract

A general thermodynamic structure for the constitutive behaviour of ferroelectric ceramics with the Perovskite structure is described. The state of the material is described in terms of the remanent strain and the remanent polarisation. A yield function is identified, such that changes in remanent strain and polarisation can only occur when the yield condition is satisfied. Simple forms of the Helmholtz free energy are presented, based on an understanding of the underlying micromechanical processes. The resulting hysteresis and butterfly loops predicted by this model are in good agreement with the general form of loops observed experimentally.