Pyrochlore-structured high-entropy rare-earth zirconates (La0.2Nd0.2Sm0.2Eu0.2A0.2)2Zr2O7 (A = Dy, Ho, or Er): Promising NTC thermistor ceramics for ultra-high temperature sensing

In this study, a series of high-entropy rare-earth zirconate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 ) 2 Zr 2 O 7 (A = Dy, Ho, or Er) ceramics containing five principal elements were synthesized via the high-temperature solid-state method, and their potential as high-temperature thermosensitive ceramics was investigated. X-ray diffraction and Raman spectroscopy confirmed the single-phase pyrochlore structural characteristics of these ceramics, while scanning electron microscopy revealed a dense microstructure. Electrical measurements demonstrated that these ceramics are capable of operating at temperatures up to 1500 °C and exhibiting exceptional sensitivity within the 400–1500 °C range, both of which are attributed to their high resistivity at elevated temperatures and a large material constant B value (≥11,241 K) across the entire operating temperature span. Notably, (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 ) 2 Zr 2 O 7 (A = Dy, Ho, or Er) ceramics also maintained a resistivity drift rate of ≤0.53 % after 500 h of continuous exposure at 1500 °C, a result ascribed to the high-entropy effect suppressing lattice distortion, as evidenced by ab initio molecular dynamics simulations. These findings validate the high-entropy strategy as a promising approach for developing durable, high-performance NTC thermistors for extreme-temperature applications.