| Abstract Scope |
Point defects govern functional properties, from carrier behavior in semiconductors to redox activity, non-stoichiometry, and transport in complex oxides. Existing approaches do not directly relate defect energetics to thermodynamic Gibbs energy models without relying on environment-dependent quantities or empirical parameters. In this presentation, we introduce the Defect Energy Formalism (DEF), a first-principles-based CALPHAD framework that establishes this connection, providing a systematic route for constructing predictive thermodynamic models of chemically and electronically driven defects. We first demonstrate DEF for dilute defects in anti-fluorite Mg₂Si, showing how vacancies, interstitials, and antisite defects from first-principles calculations can be incorporated directly into CALPHAD to predict defect concentrations, charge carriers, and phase stability. We then discuss extending DEF to high-concentration defect regimes in perovskite oxides, focusing on the Sr(Ti, Fe)O3-δ system, which exhibit high oxygen vacancy concentrations and coupled defect, redox, and configurational behavior. (1-DOI: https://doi.org/10.1103/PhysRevMaterials.8.113802)(2-SSRN: https://ssrn.com/abstract=6118126) |