화학공학소재연구정보센터
Inorganic Chemistry, Vol.53, No.17, 9206-9212, 2014
Structure, Phase Transition, and Controllable Thermal Expansion Behaviors of Sc2-xFexMo3O12
The crystal structures, phase transition, and thermal expansion behaviors of solid solutions of Sc2-xFexMo3O12 (0 <= x <= 2) have been examined using X-ray diffraction (XRD), neutron powder diffraction (NPD), and differential scanning calorimetry (DSC). At room temperature, samples crystallize in a single orthorhombic structure for the compositions of x < 0.6 and monoclinic for x >= 0.6, respectively. DSC results indicate that the phase transition temperature from monoclinic to orthorhombic structure is enhanced by increasing the Fe3+ content. High-temperature XRD and NPD results show that Sc1.3Fe0.7Mo3O12 exhibits near zero thermal expansion, and the volumetric coefficients of thermal expansion derived from XRD and NPD are 0.28 X 10(-6) degrees C-1 (250-800 degrees C) and 0.65 X 10(-6) C-1 (227-427 degrees C), respectively. NPD results of Sc2Mo3O12 (x = 0) and Sc1.3Fe0.7Mo3O12 (x = 0.7) indicate that Fe substitution for Sc induces reduction of the mean Sc(Fe)-Mo nonbond distance and the different thermal variations of Sc(Fe)-O5-Mo2 and Sc(Fe)-O3-Mo2 bond angles. The correlation between the displacements of oxygen atoms and the variation of unit cell parameters was investigated in detail for Sc2Mo3O12.