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Abstract In the study, Zr 0.5 Hf 0.5 V 2−x P x O 7 (0 ≤ x ≤ 1.2) was prepared by solid state method and then the microstructure of synthesized samples was investigated. The microstructure, coefficient of thermal expansion (CTE) and phase transition of Zr 0.5 Hf 0.5 V 2−x P x O 7 (0 ≤ x ≤ 1.2) were investigated with thermal dilatometry, x-ray diffraction (XRD) and Raman spectroscopy. The results showed that the samples were single cubic phase with the space group of Pa 3 ¯ in the crystal structure. When the substitution rate of P5+ was higher than 0.6, the 3 × 3 × 3 superstructure disappeared. The expansion coefficient of Zr 0.5 Hf 0.5 V 1.2 P 0.8 O 7 was calculated to be −0.53 × 10−6 K−1 under the linear thermal expansion in a very wide temperature range from 300 to 573 K. With the increase of P5+ content, the temperatures of positive-to-negative thermal expansion of Zr 0.5 Hf 0.5 V 2−x P x O 7 firstly even decreased below room temperature and then increased. The synthesized Zr 0.5 Hf 0.5 V 2−x P x O 7 exhibited near zero thermal expansion behavior in a wide temperature range around room temperature. Highlights • Near-zero thermal expansion behavior over a wide temperature range. • The samples are of single-phase cubic type with space group Pa 3 ¯ at RT. • The samples have low phase change temperature. • From superstructure to ideal crystal structure between 310 and 323 K. • CTE was measured by dilatometer to be 0.59 × 10−6 K−1 (310 ∼ 673 K). [ABSTRACT FROM AUTHOR]

Zr x Hf 1- x MgMo 3 O 12 with x  = 0.3, 0.5, 0.7 and 0.8 are developed with a simple solid state method. It is shown that Zr x Hf 1- x MgMo 3 O 12 ( x   =  0–1)crystallizes in an orthorhombic symmetry with space group Pnma and exhibits zero-thermal expansion in a large temperature range, with the value of x ( x  = 0.5, α l  =  −0.363 × 10 −6  K −1 from 80 K to 573 K by X-ray diffraction and α l  =  −0.25 × 10 −6 K −1 from 273 K to 673 K by dilatometer). Zr x Hf 1- x MgMo 3 O 12 with x   =  0.5 remains the orthorhombic structure without phase transition or decomposition at least from 158 K to 673 K and is not hygroscopic. These properties make it an excellent material with near-zero thermal expansion for a variety of applications. [ABSTRACT FROM AUTHOR]

An orthorhombic AlMoVO 7 was synthesized by solid-state method. Its phase, expansion property, and Raman spectra were analyzed in detail. Analysis showed that AlMoVO 7 has near-zero expansion in 173–673 K. With increasing temperature, the librational and translational vibrations of [AlO 6 ] and [MoO 4 ] caused the Al-O-Mo chain bending. The thermal expansion of AlMoVO 7 unit cell has an anisotropic and near-zero expansion. The thermal expansion performance of AlMoVO 7 block depends on its unit cell structure and microstructure. Therefore, near-zero expansion in 173–673 K is shown. [Display omitted] • AlMoVO 7 always maintains an orthogonal structure at 153–673 K. • AlMoVO 7 exhibits near-zero expansion in the temperature range of 173–673 K. • With the change of the a , b and c , AlMoVO 7 unit cell expansion is anisotropic. An orthorhombic AlMoVO 7 was synthesized by solid-state method. Its phase, expansion property, and Raman spectra were analyzed in detail. Analysis showed that AlMoVO 7 has near-zero expansion in 173–673 K. With increasing temperature, the librational and translational vibrations of [AlO 6 ] and [MoO 4 ] caused the Al-O-Mo chain bending. The thermal expansion of AlMoVO 7 unit cell has an anisotropic and near-zero expansion. The thermal expansion performance of AlMoVO 7 block depends on its unit cell structure and microstructure. Therefore, near-zero expansion in 173–673 K is shown. [ABSTRACT FROM AUTHOR]