Coexisting ferroelectric and antiferroelectric phases in dipole ordered substances. Material properties and possible applications

Comprehensive review of investigations of substances with a small difference in the energies of the ferroelectric and antiferroelectric types of dipole ordering is presented. Detailed analysis of the stability of homogeneous phases and conditions for existence of the inhomogeneous state of the substance containing domains of the coexisting ferroelectric and antiferroelectric phases is presented. It is shown that the interaction of locally separated domains of the ferroelectric and antiferroelectric phases stabilizes an inhomogeneous state of these materials. The analysis of physical phenomena caused by the presence of domains of the coexisting ferroelectric and antiferroelectric phases in different dipole ordered substances is presented. Peculiarities of behavior of the systems with the inhomogeneous state of coexisting phases under the action of changing external thermodynamic parameters (temperature, pressure, electric field, and chemical composition) are analyzed and their importance for applications of these materials is discussed.