Christopher S. Lynch

Relaxor ferroelectric single crystals of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) have outstanding electromechanical properties in the linear regime. When operated across a phase transition, these properties are significantly enhanced. Understanding the phase transition mechanism under electromechanical external fields is crucial for the new application of PMN–PT that takes advantage of this phase transition. In the present study, the phase transition of PMN–0.3PT single crystals subjected to a mechanical loading/unloading process and the effects of electric field on the phase transition and electromechanical responses of PMN–0.3PT single crystal under coupled mechanical-electrical loading were systematically investigated using a thermodynamics-based phase-field model. The roles the different energy terms play in the evolution of domain and phase structures were assessed. These findings have important implications for both understanding of the phase transition of relaxor ferroelectric single crystal PMN–0.3PT and applications that take advantage of phase transitions in these materials. The model results for the reversible/irreversible phase transition of PMN–0.3PT during the mechanical loading/unloading process are qualitatively consistent with experimental results.