Peculiarities of ferro-antiferroelectric phase transitions. 7. two phase (FE+AFE) nucleation and problem of diffusive paraelectric phase transitions

Abstract

Presented are the results of studying paraelectric phase transitions in PLLZT solid solutions near the triple ferro-antiferro-paraelectric point. Analysis of X-ray patterns shape allows to conclude that in solid solutions, for which ferro- and antiferroelectric states have a low energy difference, two-phase (FE+AFE) nuclei exist above the Curie point.

A model of diffusive phase transitions near the triple point is discussed. The model takes into account stratification of the solid solutions in local regions of the crystal in the vicinity of the inter-phase FE-AFE boundary. The possibility to apply the proposed model to a wide class of ferro- and antiferroelectrics which show diffusive phase transition, is discussed.