Phenomenological theory of a single domain wall in uniaxial trigonal ferroelectrics: lithium niobate and lithium tantalate

TL;DR

This paper develops a phenomenological model for domain walls in uniaxial trigonal ferroelectrics lithium niobate and lithium tantalate, analyzing their energy and configurations to match experimental observations.

Contribution

It introduces analytical expressions for domain wall energy considering polarization and strain, revealing preferred wall orientations in these materials.

Findings

Hexagonal y-walls are energetically favored over x-walls.

Model predictions align with experimental domain geometries.

Analytical approach aids understanding of domain wall behavior.

Abstract

A phenomenological treatment of domain walls based on the Ginzburg-Landau-Devonshire theory is developed for uniaxial, trigonal ferroelectrics lithium niobate and lithium tantalate. The contributions to the domain wall energy from polarization and strain as a function of orientation are considered. Analytical expressions are developed which are analyzed numerically to determine the minimum polarization, strain, and energy configurations of domain walls. It is found that hexagonal y-walls are preferred over x-walls in both materials. This agrees well with experimental observation of domain geometries in stoichiometric composition crystals.