Composition- and pressure-induced ferroelectric to antiferroelectric phase transitions in Sm-doped BiFeO₃ system

A three-dimensional phenomenological model is proposed to describe both ferroelectricity and antiferroelectricity based on the Ginzburg-Landau-Devonshire theory. Its application to the multiferroic Sm-doped BiFeO₃ system describes the temperature-, pressure-, and composition-induced ferroelectric to antiferroelectric phase transitions. The constructed temperature-composition and temperature-pressure phase diagrams show that compressive hydrostatic pressure and Sm doping have similar effects on the ferroelectric and antiferroelectric phase transitions. It is also indicated from the temperature-pressure phase diagram that the experimentally observed phase of BiFeO₃ under the hydrostatic pressure from 3 GPa to 10 GPa is a PbZrO₃-like antiferroelectric phase.