Ultra-temperature and high thermal stability thermosensitive high-entropy ceramics up to 1873 K

Abstract

High ceiling temperature and the 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, a (Ho_0.2Er_0.2Tm_0.2Yb_0.2Lu_0.2)₃NbO₇ high-entropy ceramic is reported which possesses exceptional thermosensitive capability and high thermal stability. With the structure construction involving constraining a 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 1873 K. 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 temperatures up to 1873 K. This work provides 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 measurement applications.