Materials Research Bulletin, Vol.99, 255-259, 2018
Phase transition and negative thermal expansion of HfMnMo3O12
A novel compound HfMnMo3O12 with negative thermal expansion (NTE) was synthesized using solid state method. The crystal structure, fracture morphology and NTE properties of the material were investigated by temperature-dependent X-ray diffraction (XRD), scanning electron microscope (SEM) and temperature-dependent Raman spectra. Our experimental results show that the compound adopts a monoclinic symmetry below room temperature and transforms to an orthorhombic phase above 348 K. In the orthorhombic phase the compound exhibits NTE property with a linear coefficient of thermal expansion (CTE) -3.8 x 10(-6) K-1 from 400 K to 700 K. The physical mechanism of the NTE is discussed and elucidated according to our experiments.