To meet the application demands in extreme high-temperature environments such as condition monitoring of aerospace engine and thermal management systems of new energy vehicle, high-temperature thermosensitive sensors must simultaneously possess high stability and sensitivity characteristics in a wide temperature range. Conventional thermosensitive materials are prone to performance instability under extreme temperatures, while emerging high-entropy materials demonstrate exceptional thermal/chemical stability and synergistic strengthening mechanisms through the entropy-stabilization effect. However, their strong lattice disorder leads to a sharp decline in carrier mobility, causing exacerbated electron scattering and deterioration of electrical transport performance, which severely limits the resistance-temperature response accuracy at elevated temperatures. Consequently, developing novel thermosensitive material that can balance the conflict in lattice stability and carrier transport efficiency has become the key to advancing high-precision sensing technologies.

To address this challenge, researchers from the Department of Materials Physics and Chemistry at the Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, have successfully developed high-entropy thermosensitive ceramics based on rare-earth niobates (ReNbO₄, where Re are rare-earth elements) with fergusonite-type structures, utilizing an oxygen vacancy regulation strategy. The synergistic effect between entropy stabilization (induced by multi-component rare-earth ion doping at A-sites) and Sr²⁺ allovalent doping significantly enhances oxygen vacancy concentration, thereby optimizing the material's electron transport characteristics and lattice stability. The study demonstrates that the oxygen vacancy-induced entropy stabilization strategy concurrently modulates the material's microstructure, forming stabilized features such as twin domains, lattice distortions, and dynamic reconstruction, which effectively improves both the linearity of temperature-resistance response and high-temperature stability. The synthesized material exhibits exceptional environmental adaptability (applicable in a wide temperature range from 223 K to 1423 K), high thermal stability (aging drift is less than 1% after 1000 hours high temperature aging) and temperature coefficient of resistance (0.223 %/K at 1423 K), providing theoretical guidance for designing novel thermosensitive ceramics for extreme environments.

The paper was published in Small with a title of "Synergistic Entropy Engineering with Oxygen Vacancy: Modulating Microstructure for Extraordinary Thermosensitive Property in ReNbO₄ Materials". The Xinjiang Institute of Physics and Chemistry, Chinese Academy of Sciences, is the sole corresponding affiliation. This work was supported by the National Natural Science Foundation of China, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, the Natural Science Foundation of Xinjiang Uygur Autonomous Region, and the Xinjiang Tianshan Training Program.

Figure. Relationship Between Microstructure and Properties of High-Temperature Thermosensitive Ceramics (Image by Prof. CHANG Aimin's group)