Formation energy profiles of oxygen vacancies at grain boundaries in perovskite-type electroceramics

TL;DR

This study uses atomistic calculations to analyze how oxygen vacancy formation energies vary across different grain boundaries in perovskite electroceramics, affecting defect redistribution and material properties.

Contribution

It provides detailed atomistic profiles of oxygen vacancy formation energies at various grain boundaries in SrTiO₃, BaTiO₃, and BaZrO₃, revealing the influence of boundary type and composition.

Findings

Oxygen vacancy formation energies vary significantly across grain boundaries.

Grain boundary type and composition influence defect energetics.

Profiles help understand defect redistribution in electroceramics.

Abstract

Oxygen vacancy formation energies play a major role in the electric field assisted abnormal grain growth of technologically relevant polycrystalline perovskite phases. The underlying effect on the atomic scale is assumed to be a redistribution of cationic and anionic point defects between grain boundaries and the bulk interior regions of the grains due to different defect formation energies in the structurally different regions, accompanied by the formation of space charge zones. Using atomistic calculations based on classical interatomic potentials, we derive and discuss optimized structures of the symmetric tilt grain boundaries $\Sigma$5(210)[001] and $\Sigma$5(310)[001], and of the asymmetric tilt grain boundary (430)[001]||(100)[001] in the electroceramic perovskite materials SrTiO$_3$, BaTiO$_3$, and BaZrO$_3$. We present profiles of oxygen vacancy formation energies across those GBs and discuss their dependence on composition and grain boundary type.