Peculiarities of ferro-antiferro-electric phase transitions. 3. Phenomenological approach to the problem of fe and afe phases coexistence. Nonuniform state

Abstract

A phenomenological description of the effects originating in the coexistence of FE and AFE phases is presented. The behaviour of the discussed systems is analysed in the frame of the Landau phenomenological model on the base of the thermodynamic potential taking into account the order parameters of the both mentioned phases. The interaction of domains of FE and AFE phases is taken into consideration.

It is shown that in some cases the interphase interaction leads to a negative value of the interphase surface energy. The latter stabilizes the nonuniform state of the coexisting FE and AFE phases. The discussion of the effects caused by the interphase interaction is presented.

Keywords:

• Ferroelectric
• antiferroelectric
• phase transitions
• interphase interaction
• phase coexistence