Landau theoretical analyses of phase transitions and ferroelec-tricity in antiferroelectric ferroics

This paper presents Landau theoretical interpretation of phase transitions in Antiferroelectrics (AFEs) materials. The results show that the phase transitions occurring in AFEs have prominently first and second order properties. Landau theories of first and second order phase transition have been appropriately analyzed in order to explain some of desirable phenomenological behaviors occurring in AFE materials. The spatial order parameter profile of AFE domain wall was derived and tested for possibilities of having ferroelectricity (FE) in accordance with Landau type energy functional. It was found that FE may appear but with additional system instability because of additional energy as a result of polarization gradient.