Inter-defect interactions, oxygen-vacancy distribution, and oxidation in acceptor-doped ABO3 perovskites

TL;DR

This study uses statistical theory and Monte Carlo simulations to analyze how inter-defect interactions and impurity disorder influence defect thermodynamics, oxidation, and local ion coordination in acceptor-doped ABO3 perovskites.

Contribution

It reveals the dominant role of impurity-oxygen vacancy interactions over vacancy-vacancy correlations and explains their effects on material properties and hole conductivity.

Findings

Oxygen vacancy-impurity interactions have a greater impact than vacancy-vacancy correlations.

Impurity distribution significantly affects oxygen-vacancy distribution.

Inter-defect interactions influence hole concentration and oxidation enthalpy.

Abstract

The effects of inter-defect interaction and impurity disorder on defect thermodynamics, local ion coordination, and oxidation in acceptor-doped wide-gap ABO3 perovskites are explored using the developed statistical theory and Monte Carlo simulations. The results demonstrate that under realistic energy parameters the interaction between oxygen vacancies and impurities generally has a greater impact on the studied properties than inter-vacancy correlations. The influence of inter-vacancy interaction significantly depends on dopant content x: inter-site vacancy repulsion becomes noticeable at sufficiently high x, whereas on-site correlations can be pronounced within a narrow doping range at moderate x values. It is found that a non-uniform impurity allocation, which can result from a sample preparation procedure, considerably affects oxygen-vacancy distribution, and has a weaker effect on short-range order and oxidation. It is also shown that inter-defect interaction reduces the hole concentration, increases the oxidation enthalpy, and can result in their non-trivial dependence on x. The obtained results agree with experimental data on local ion coordination and help to explain the behavior of hole conductivity in the considered perovskites. The findings of this study contribute to understanding the fundamental properties of acceptor-doped oxides, facilitating the development of new materials for clean energy applications.