The effect of mechanical strains on the ferroelectric and dielectric properties of a model single crystal - Phase field simulation

The effect of applied mechanical strains on the ferroelectric and dielectric properties of a model single crystal is investigated using a phase field model based on the time-dependent Ginzburg-Landau equation, which takes both multiple-dipole-dipole-clectric and -elastic interactions into account. The evolution of the ferroelectric domain structure is simulated at different temperatures and applied strains. The results show that the paraelectric/ferroelectric phase transition temperature linearly increases with the applied mechanical strain under mechanical clamping conditions. Analogous to the classical Ehrenfest equation, a thermodynamics equation is derived to describe the relationship between the transition temperature and the applied strain. The change in the domain structure with temperature under applied inequiaxial strains is different from that under applied equiaxial strains. The simulations also illustrate the changes in the coercive field, the remanent polarization and the nonlinear dielectric constant with the applied strain. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.