Ultra-temperature and High Thermal Stability Thermosensitive High-Entropy Ceramics up to 1873 K

Abstract

High ceiling temperature and corresponding thermal stability are crucial to thermo-sensitive materials under extreme conditions. However, these features are often difficult to achieve simultaneously in conventional thermo-sensitive ceramics, thus becoming a key bottleneck restricting the development of thermo-sensitive ceramics in next-generation advanced high-temperature sensors. Here, for the first time, it is reported a (Ho0.2Er0.2Tm0.2Yb0.2Lu0.2)3NbO7 high-entropy ceramic which possesses exceptional thermosensitive capability and high thermal stability. With the structure construction involving constraining NbO6 octahedron by tailoring the lattice distortion and solving the stability degeneration caused by the tilt of the NbO6 octahedron and dipolar interactions of the off-centered Nb cations, the materials with highly dense lattice distortion dominated by symmetric tensile-compressive strains exhibit thermo-sensitive characteristics from 623 k to 1873K. More importantly, the materials demonstrate exceptional thermal stability, with an aging coefficient of less than 1 % after aging at 1873 K for 400 h. They also show an ultrahigh measurement accuracy (R2 as high as 999.92 ‰ and RSS as low as 0.071) maintaining excellent sensitivity at high temperatures up to 1873 K. This work opens an effective way to design high-temperature thermosensitive ceramics with high ceiling temperature and high thermal stability to meet the demanding requirements of advanced high-temperature temperature measurement applications.