Hu Zhongbo

Thermal expansion properties of Lu2−x FexMo3O12

The structures and thermal expansion properties of Lu2−xFexMo3O12 have been investigated by X-ray diffraction (XRD). XRD patterns at room temperature indicate that compounds Lu2−xFexMo3O12 with x ≤ 1.3 exhibit an orthorhombic structure with space group Pnca; compounds with x = 1.5 and 1.7 have a monoclinic structure with space group P21/a. Studies on thermal expansion properties show that the linear thermal expansion coefficients of orthorhombic phase vary from negative to positive with increasing Fe content. Attempts to make zero thermal expansion materials indicate that zero thermal expansion can be observed in Lu1.3Fe0.7Mo3O12 in the temperature range of 200–400 °C.

Thermal expansion properties and hygroscopicity of Y2−x Sm x W3O12 (x = 0.0–0.4) compounds

A novel class of solid solutions of Y2−xSmxW3O12 (x = 0.0−0.4) were synthesized and studied by means of powder X-ray diffraction. All samples crystallize in an orthorhombic space group Pnca. The lattice parameters a, b and c of Y2−xSmxW3O12 increase with increasing Sm content. Since the compounds of this series hydrate at room temperature, thermogravimetric (TG) analysis was carried out. The result shows that the compound stores less water with increasing Sm content. The thermal expansion properties of Y2−xSmxW3O12 (x = 0.1, 0.3 and 0.4) were investigated with high temperature X-ray diffraction. Negative thermal expansion coefficient αI becomes less negative from −6.644×10−6 to −6.211×10−6°C−1 when x changes from 0.1 to 0.4.