Achieving near-zero thermal expansion in high-entropy ceramic (Ti1/3Zr1/3Hf1/3)Sc <i>x</i> Fe1− <i>x</i> Mo2VO12

Abstract

Near-zero thermal expansion materials exhibit minimal volume changes under extreme temperature fluctuations, offering significant application value in high-precision instruments, optical equipment, satellite technology, and other fields. In this study, the (Ti1/3Zr1/3Hf1/3)ScxFe1−xMo2VO12 ceramic system was designed using a high-entropy solid solution strategy. The study indicates that the high-entropy effect at the A site due to Sc3+ doping successfully suppresses the Fe2Mo3O12 phase transition temperature from 773 K to below 173 K when x ≥ 0.75, achieving a stable orthorhombic phase and near-zero thermal expansion (173–673 K) with a volumetric thermal expansion coefficient of αv = 1.2 × 10−6 K−1. Variable-temperature XRD and Raman spectroscopy reveal that the microscopic mechanism stems from the synergistic interaction between lattice anisotropy (a-axis expansion and b/c-axis contraction) and the positive anharmonicity of the 332 cm−1 vibrational mode. The material exhibits outstanding thermal stability up to 1273 K, offering a novel material solution for precision thermal management devices across a broad temperature range.