Zero and controllable thermal expansion in ☆☆Project supported by the National Natural Science Foundation of China (Grant Nos. 10974183 and 11104252), the Key Natural Science Project of Henan Province, China (Grant No. 142102210073), the Doctoral Fund of the Ministry of Education of China (Grant No. 20114101110003), and the Fund for Science & Technology Innovation Team of Zhengzhou, China (Grant No.

Abstract

HfMgMo WxO12 with , 1.0, 1.5, 2.0, and 2.5 are developed with a simple solid state method. With increasing the content of W, solid solutions of HfMgMo WxO12 crystallize in an orthorhombic structure for and a monoclinic structure for . A near-zero thermal expansion (ZTE) is realized for HfMgMo W O12 and negative coefficients of thermal expansion (NCTE) are achieved for other compositions with different values. The ZTE and variation of NCTE are attributed to the difference in electronegativity between W and Mo and incorporation of a different amount of W, which cause variable distortion of the octahedra and softening of the MoO4 tetrahedra, and hence an enhanced NCTE in the a- and c-axis and reduced CTE in the b-axis as revealed by Raman spectroscopy and x-ray diffraction.