Impact of A-site deficiency on the structural, thermal, and ionic transport properties of SrTiO ₃ : A molecular dynamics study

This study investigates the impact of A-site deficiency on the structural, thermal, and ionic properties of strontium titanate (SrTiO[Formula: see text], a material of interest for high-temperature applications such as solid oxide fuel cells and thermal sensors. Using molecular dynamics simulations, Sr[Formula: see text]TiO[Formula: see text] compositions with [Formula: see text], 0.025, 0.05, 0.10, 0.15, and 0.20 were examined across a temperature range of 973–1373[Formula: see text]K to understand the relationship between compositional variations and material behavior. The introduction of A-site deficiency led to the formation of oxygen vacancies, causing a consistent reduction in lattice constants while preserving cubic symmetry. Thermal expansion coefficients followed linear trends, with deviations at higher deficiency levels ([Formula: see text]) and temperatures ([Formula: see text][Formula: see text]K), suggesting possible thermally-induced phase transitions. Oxygen anion diffusivity exhibited a non-monotonic trend, peak value at [Formula: see text][Formula: see text]m 2 /s at 1373[Formula: see text]K for Sr[Formula: see text]TiO[Formula: see text] Arrhenius plots revealed that activation energy for oxygen anion diffusion decreased to 0.50[Formula: see text]eV with increasing deficiency up to 7.5%, indicating the formation of enhanced diffusion pathways. Beyond this optimal deficiency, ionic mobility declined. These results provide quantitative insights into defect-driven ion transport and thermal stability in perovskite materials.