Microstructural Engineering Enables Record Thermal Endurance of Metal Oxide Thin Films in Extreme Environments

Abstract High‐temperature thin‐film sensors (HTTSs) offer promising solutions for in situ monitoring of various thermal and mechanical parameters in extreme environments. However, maintaining their stable operation at high temperatures exceeding 1000 °C for extended durations remains challenging due to severe material degradation. This study first demonstrates a microstructural engineering strategy to enhance the thermal endurance of metal oxide thin films through integrating high‐melting‐point metal oxide nanophases. Using standard Micro‐Electro‐Mechanical System (MEMS) technologies, alumina (Al₂O₃) is atomically integrated into indium tin oxide (ITO) thin films. The influence of Al₂O₃ doping on the ITO matrix under various high‐temperature conditions, with emphasis on the variations of chemical composition, crystal structure, morphology, recrystallization, and sensing behavior, is systematically investigated. An optimized film, characterized by an Al/In ratio of 1.57 wt.%, exhibits a record‐low resistance drift of 0.002% h⁻¹ during a 10 h exposure at 1200 °C.