Researchers develop high-entropy ceramic for high-temperature sensors

As aeroengine thrust-to-weight ratios continue to improve, the operating temperature of their hot-end components has risen steadily, placing stricter demands on the performance of temperature sensors. Among potential solutions, negative temperature coefficient (NTC) thermistors—known for their low cost, small size, and fast response—are emerging as a promising candidate for next-generation advanced temperature sensors. However, extreme high-temperature environments pose significant challenges to the structural and electrical stability of thermosensitive ceramics, the core component of such thermistors.

To tackle this issue, a research team from the Xinjiang Institute of Physics and Chemistry (XTIPC) of the Chinese Academy of Sciences has developed a rare-earth tantalate (RETaO₄) thermosensitive ceramic using a high-entropy strategy. Their findings were published in the Journal of Materials Chemistry A.

The researchers introduced a large number of diverse [REO₈] polyhedra into the material system, which induces substantial lattice distortion. This distortion overlaps and compensates with the pre-existing distortions of interconnected [TaO₆] polyhedra in the original structure, creating a “localized alternating tension strain.” This synergistic compensation effect enhances both the structural and electrical stability of the material.

The synthesized (HoErTmYbLu)_0.2TaO₄ high-entropy ceramic demonstrates exceptional measurement sensitivity across an ultra-wide temperature range (673–1773 K). In continuous testing over 180 seconds, it exhibits a low relative standard deviation (RSD) of resistance at 0.0311. After 50 hours of aging, its aging coefficient stabilizes with fluctuations limited to 3%.

The research highlights the high-entropy strategy’s potential in designing high-performance, high-temperature thermosensitive ceramics.