Phase Transition and Negative Thermal Expansion Property of ZrMnMo3O12**Supported by the National Natural Science Foundation of China under Grant Nos 11574276, 51503185 and 51302249, and the Doctoral Fund of the Ministry of Education of China under Grant No 20114101110003.

Abstract

A novel material of ZrMnMo3O12 with negative thermal expansion is presented. The phase transition temperature and coefficient of thermal expansion (CTE) are investigated by temperature-dependent x-ray diffraction and Raman spectra. It is shown that ZrMnMo3O12 adopts monoclinic structure with space group P21/a (No. 14) from 298 to 358 K and transforms to orthorhombic with space group Pnma (No. 62) above 363 K. The linear CTE obtained from the results of XRD refinement is −2.80 × 10−6 K−1 from 363 to 873 K. The CTE of the bulk cylinder ceramic measured by a thermal dilatometer is −4.7 × 10−6 K−1 from 373 to 773 K approximatively.