Reliable temperature monitoring is essential for hypersonic vehicles, aero-engines, gas turbines, and advanced energy-conversion systems, where critical components may operate above 1000 °C for extended periods. Negative-temperature-coefficient (NTC) thermistors offer high sensitivity, rapid response, compact size, and integration potential. However, conventional thermistor ceramics often undergo phase decomposition, cation migration, defect redistribution, grain coarsening, and interfacial degradation at elevated temperatures. These changes can cause nonlinear resistance–temperature behavior and progressive signal drift, limiting measurement accuracy and long-term reliability.
A research team led by Bo Zhang at the Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, has developed Mo-regulated high-entropy niobate ceramics for linear and stable thermal sensing over an ultrawide temperature range. The study addresses a central challenge in high-temperature sensing: achieving high linearity and long-term stability simultaneously, rather than improving the maximum operating temperature alone.
The team published their work in Journal of Advanced Ceramics on July 10, 2026.
The researchers designed a series of ferroelastic high-entropy ceramics with the composition (Ca0.2La₀.₂Ce0.2Eu0.2Gd0.2)Nb1-xMoxO4. The ceramics were fabricated through a conventional solid-state reaction followed by a two-step sintering process. After ball milling, the mixed oxide powders were calcined at 1100 °C, pressed into disks, heated to 1400 °C to initiate densification, and then cooled to 1280 °C for prolonged holding. This processing route was selected to promote pore shrinkage while restricting excessive grain-boundary migration and grain growth.
Density functional theory calculations showed that the chemically complex A-site environment made Mo substitution at Nb sites energetically more favorable than in a conventional CeNbO4 lattice. Structural analyses confirmed that compositions with Mo contents up to x = 0.2 retained the monoclinic C2/c framework. X-ray diffraction, high-resolution transmission electron microscopy, aberration-corrected scanning transmission electron microscopy, atomic-displacement analysis, and strain mapping were then used to examine how Mo altered the local structure.
The results showed that Mo incorporation broadened the distribution of local cation configurations and increased the average cation-displacement amplitude from 12.02 to 18.16 pm. It also modified the spacing and arrangement of ferroelastic twin domains and generated a more heterogeneous nanoscale strain environment. These structural changes did not simply increase disorder; they reshaped the localized energy barriers governing carrier migration.
"The objective was not merely to introduce more compositional complexity," Zhang said in a proposed statement for the release. "The team sought to use high-entropy chemistry and Mo regulation to coordinate local lattice distortion, carrier transport, and grain-boundary behavior. This produced a more balanced transport-energy landscape and helped maintain a smooth, calibratable response across a very broad temperature range."
Temperature-dependent Hall measurements and high-temperature impedance spectroscopy were used to clarify the electrical transport mechanism. The Hall results revealed compensating changes in carrier concentration and mobility at elevated temperatures, allowing resistivity to evolve smoothly despite a redistribution of transport contributions. Impedance analysis further separated grain and grain-boundary responses. For the optimized HEN-0.2Mo ceramic, the grain and grain-boundary activation energies were 1.209 and 1.218 eV, respectively, corresponding to a mismatch of only about 0.009 eV. This close barrier matching reduced transitions between competing conduction processes.
As a result, the optimized ceramic exhibited highly linear Arrhenius behavior from −50 to 1250 °C, with a coefficient of determination of 0.99907 and a B-value fluctuation of only 4.44%. Comparative measurements showed that other Mo concentrations produced larger activation-energy mismatches and less balanced transport behavior.
The team also conducted accelerated aging tests at 1250 °C for 1000 hours. After the initial sensitization stage, the optimized ceramic showed a stabilized-stage resistance drift of only 1.09%. Its relative density increased from 83.6% to approximately 91.3%, while strain analysis indicated redistribution and homogenization of the local stress field. The researchers attributed the enhanced stability to aging-induced post-densification, controlled grain growth, grain-boundary relaxation, and ferroelastic strain accommodation rather than to a fully established intrinsic self-healing mechanism.
The findings provide a mechanism-based route for designing thermistor ceramics that combine ultrawide-range response, high linearity, and resistance to prolonged thermal degradation. The material is a promising candidate for temperature monitoring in hypersonic propulsion, aero-engines, high-temperature reactors, and advanced energy systems. Further work will be required to integrate the ceramic into packaged sensors and to establish standardized pre-aging and recalibration procedures before practical deployment.
Other contributors include Hao Sun, Jianan Xu, Xuemei Jia, Jia Chen, Wenyuan Li, from the Center of Materials Science and Optoelectronics Engineering of University of Chinese Academy of Sciences and Xinjiang Technical Institute of Physics & Chemistry of CAS, China; Hanao Deng, Congwei Xie, Yafei Liu, Ruifeng Wu and Aimin Chang from the Xinjiang Technical Institute of Physics & Chemistry of CAS, China.
About Author
Bo Zhang is a professor and doctoral supervisor at the Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. His research focuses on the development and practical application of high-temperature thermosensitive ceramic materials and devices. He is an Outstanding Member of the Youth Innovation Promotion Association of the Chinese Academy of Sciences, a recipient of the 10th Xinjiang Youth Science and Technology Award, and a selected participant in the Xinjiang Tianshan Talents Programs. He has also received the Xinjiang Outstanding Young Scientists Fund and the Chinese Academy of Sciences President's Award, and was a visiting scholar at Alfred University. As first or corresponding author, Zhang has published 73 SCI-indexed papers in journals including Journal of Advanced Ceramics, Chemical Engineering Journal, Small, Journal of Materials Chemistry A, Applied Physics Letters, Journal of the European Ceramic Society, Journal of the American Ceramic Society, and ACS Applied Materials & Interfaces. He is the first inventor of 13 granted Chinese invention patents, three of which have been transferred for application. He has led more than 20 national and provincial research projects, including three projects funded by the National Natural Science Foundation of China. His research has received several major awards, including the First Prize of the Xinjiang Science and Technology Progress Award.
Funding
This work was supported by the National Natural Science Foundation of China (Grant No. 62471468), Xinjiang Tianshan Talent Training Program (Grant No. 2023TSYCCX0092), Natural Science Foundation of Xinjiang (Grant No. 2024D01E32), Tianshan Innovation Team Plan of Xinjiang (Grant No. 2025D14011), and Youth Innovation Promotion Association of CAS (Grant No. Y2023117).
DOI: 10.26599/JAC.2026.9221348
About Journal of Advanced Ceramics
Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen . JAC's 2025 IF is 14, ranking in Top 1 (1/34, Q1) among all journals in "Materials Science, Ceramics" category, and its 2025 CiteScore is 24.6 (6/133) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508
