Synergistic Entropy Engineering with Oxygen Vacancy: Modulating Microstructure for Extraordinary Thermosensitive Property in ReNbO 4 Materials

Abstract The pursuit of high precision and stability simultaneously in high‐temperature thermistor fields is longstanding. However, most spinel or perovskite‐structured thermosensitive materials struggle to tolerate prolonged high‐temperature environments at the expense of sensitivity and stability. Here, a novel entropy engineering strategy involving vacancies is proposed to balance sensitivity and stability for fergusonite‐structured ReNbO 4 (Re is a rare earth element) material in extreme environments. The synergistic effect of entropy stabilization and allovalent substitution on the A‐site generates unusually high concentrations of oxygen vacancy that improves the electronic structure and structural stability. Moreover, entropy engineering involving oxygen vacancies introduces potent and stable microstructural features including twinned domains, lattice distortion, and lattice reconfigurations, which facilitate stability and accuracy at a wide temperature range, thereby synergistically contributing to excellent thermosensitive properties. As‐prepared high‐entropy ceramics show low aging drift rates and high‐temperature measurement accuracy over the extended temperature range of 223–1423 K, exhibiting a competitive temperature coefficient of resistivity of 0.223%/K at 1423 K. This work not only provides valuable insights into the design of high‐temperature thermosensitive sensors but also establishes an effective paradigm for entropy engineering involving vacancies.