Theory of morphotropic phase boundary in solid solution systems of perovskite-type oxide ferroelectrics: Engineered domain configurations

Polarization-field and strain-field hysteresis loops with held-induced transition in two types of engineered domain configurations in perovskite-type oxide ferroelectrics were calculated in terms of the Landau-Devonshire type free energy. Using the free energy function truncated at the fourth order with respect to the polarization, it was found that the field-induced transition from the tetragonal phase to the rhombohedral phase under the field along the [111] direction is of the first order, while the transition from the rhombohedral phase to the tetragonal phase under the field along the [001] direction is of che second order. Physical properties of the engineered domain configurations were discussed.