High-precision and high-stability NTC thermistors driven by hole-electron bipolar conduction mechanism

Negative temperature coefficient (NTC) thermistors are critical components in electronic circuits for overheat protection, owing to their exceptional temperature compensation properties. However, the susceptibility of the inherent spinel structure to degradation in low-oxygen environments limits their operational stability. We report the design of a robust inverse spinel-perovskite-fluorite three-phase heterostructure, achieved by combining heterojunction and entropy engineering to withstand low-oxygen environments. By optimizing Mn doping and regulating R-O bonds, the high-temperature/low-oxygen grain boundary resistance is minimized to 0.55 Ω·cm. This specific architecture effectively suppresses interphase elemental diffusion and stabilizes manganese ions entirely as Mn 2+ . Consequently, the ceramics exhibit exceptional environmental stability, featuring restricted room-temperature resistance ( R 25 ) and material constant ( B 25/50 ) drifts of 0.93% and 0.11%, respectively, alongside a minimal aging rate of 0.2% after 600 h in air. A substantial room-temperature temperature coefficient of resistance (TCR) of −5.98% ensures high-precision sensing capabilities. Density functional theory (DFT) calculations reveal that La and Ce dopants establish high energy barriers against elemental migration, while an internal electric field and interfacial coupling synergistically stabilize the hole-electron conduction mechanism. This study provides a compelling ceramic heterostructure paradigm for advanced sensing in extreme environments.