Insight into perovskite antiferroelectric phases: Landau theory and phase field study

The appearance of commensurate and incommensurate modulations in perovskite antiferroelectrics (AFEs) is not understood. And the elastic property of the AFE domain boundaries is lack of investigation. In this work, a novel Landau theory is proposed to understand the transformation of AFE commensurate and incommensurate phases, by considering the coupling between the oxygen octahedral tilt mode and the polar mode. The relationship between the modulation periodicity and temperature is obtained. Using the phase field study, we show that the suppressed polarization at the AFE domain boundaries can lead to a remanent polarization and local elastic stress field. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.