Preparation and negative thermal expansion in medium-entropy ceramics (Zr1/3Hf1/3Ti1/3)V2O7

The negative thermal expansion material ZrV2O7 exhibits superior performance and holds significant potential for applications. In this study, the medium entropy concept was employed to successfully synthesize (Zr1/3Hf1/3Ti1/3)V2O7, with metal atoms (Ti, Zr, and Hf) occupying the position of Zr in ZrV2O7. The material shows a negative thermal expansion coefficient of 4.2 × 10-6K-1, which is essentially consistent with the crystal structure and expansion performance of ZrV2O7. However, (Zr1/3Hf1/3Ti1/3)V2O7 demonstrates higher softening temperature and thermal stability. This study simplified the complex preparation process of the material, broadening its negative thermal expansion range and enhancing its high-temperature stability. Furthermore, the material possesses a significant dielectric constant of 2.24 × 108 (log f <1) and a high hardness of 187.7 HV0.5, making it a new type of dielectric ceramic material. It has great potential for applications in the fields of energy storage and electronic packaging.