Suppressing intrinsic self-compensating of BaSm2Ti4O12-δ ceramics for high-temperature thermistor application

Abstract

BaSm₂Ti₄O₁₂ (BSTO) material is promising for high-temperature thermistor applications owing to its excellent thermal stability and sensitivity coefficients. However, above 973 K, the increase in oxygen vacancies triggers the self-compensating effect of BSTO, leading to a de-localization of the localized states in the forbidden band and electrical properties deviating from the Arrhenius equation. Herein, we propose a Passive Variable-Range Hopping (PVRH) conduction mechanism to explain the nonlinear nature. Meanwhile, we suppress oxygen vacancy formation using Tb^3.5 + doping and enhance structural stability through high-temperature aging, ensuring the electrical properties of BSTO materials follow the Arrhenius equation. In particular, the electrical properties of the BaTb_0.2Sm_1.8Ti₄O_12-δ sample demonstrate an excellent linear correlation with the Arrhenius equation, achieving a Pearson coefficient of 99.992 % across 723–1273 K. and maintaining a sensitivity coefficient as high as −1.28 % at 1273 K. This study provides valuable theoretical support for the development of high-temperature thermistors with high-precision.