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 field-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 the second order. Physical properties of the engineered domain configurations were discussed.