Finite-Temperature Atomic Structure of 180^o Ferroelectric Domain Walls in PbTiO3

TL;DR

This study models the finite-temperature atomic structure of 180° ferroelectric domain walls in PbTiO3, revealing temperature-dependent thickness changes and energetic preferences for Ti-centered walls.

Contribution

It introduces a quasi-harmonic lattice dynamics method to analyze temperature effects on domain wall structures in PbTiO3.

Findings

Domain walls are thicker at room temperature.

Ti-centered domain walls have lower free energy.

Thickness increases by about three times from 0K to 300K.

Abstract

In this letter we obtain the finite-temperature structure of 180^o domain walls in PbTiO3 using a quasi-harmonic lattice dynamics approach. We obtain the temperature dependence of the atomic structure of domain walls from 0K up to room temperature. We also show that both Pb-centered and Ti-centered 180^o domain walls are thicker at room temperature; domain wall thickness at T=300K is about three times larger than that of T=0K. Our calculations show that Ti-centered domain walls have a lower free energy than Pb-centered domain walls and hence are more likely to be seen at finite temperatures.