Phase transition and near-zero thermal expansion of Zr0.5Hf0.5VPO7**Project supported by the National Natural Science Foundation of China (Grant Nos. 11574276, U173112, and 41401384), the Project of Shandong Provincial Higher Educational Science and Technology Program, China (Grant No. J17KB127), the Science and Technology Development Plans of Binzhou City, China (Grant Nos. 2014ZC0307 and 2015ZC0210), and Binzhou University Research Fund Project, China

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The Zr0.5Hf0.5VPO7 is successfully synthesized by the solid-state method with near-zero thermal expansion. Powder x-ray diffraction (XRD), Raman spectroscopy, thermal dilatometry, and scanning electron microscopy (SEM) are used to investigate the structure, the phase transition, and the coefficient of thermal expansion (CTE) of Zr0.5Hf0.5VPO7. The investigation results show that the samples are of the single cubic type with a space group of at room temperature (RT). It can be inferred that the superstructure is transformed from the 3 × 3 × 3 superstructure to the 1 × 1 × 1 ideal crystal in a temperature range between 310 K and 323 K. The CTE is measured by a dilatometer to be 0.59 × 10−6 K−1 (310 K–673 K). The values of intrinsic (XRD) and extrinsic (dilatometric) thermal expansion are both near zero. The results show that Zr0.5Hf0.5VPO7 has near-zero thermal expansion behavior over a wide temperature range.