Temperature‐dependent electromechanical response of BaTi ₁ ₋ <i> _x </i> Sn <i> _x </i> O ₃ : Analysis of reversible and irreversible contributions

Abstract The increasing demand for efficient, multifunctional energy conversion systems has sparked interest in light‐active polar perovskite oxides. These materials offer structural flexibility and chemical tunability, making them promising candidates for multimodal energy harvesting. In particular, photoferroelectrics enable the simultaneous harvesting of thermal, light, and mechanical energy. However, mostly room temperature properties have been studied, leaving a critical gap in understanding their behavior under varying thermal conditions. This study investigates the electromechanical properties in conjunction with crystallographic changes of photoferroelectric BaTi 1 ₋ x Sn x O 3 across a temperature range of −150°C to 150°C. Increasing Sn content reduces tetragonal distortion, shifts phase transition temperatures, and induces a multi‐phase region at higher concentrations. As a result, temperature‐dependent small‐signal measurements show changes in dielectric and piezoelectric responses, with a trend toward relaxor‐like behavior at higher Sn levels. Rayleigh analysis of stress amplitude‐dependent piezoelectric coefficient reveals enhanced properties at specific compositions, for example, 7 mol% Sn) and temperatures, attributed to an optimal balance of reversible and irreversible contributions. Further, Sn doping appears to improve thermal stability by reducing irreversible contributions. These results provide significant implications for optimizing photoferroelectric BaTiO 3 by influencing material properties through Sn doping for various applications, including energy harvesting.