Thermal expansion properties of Lu_2-x Fe_xMo₃O₁₂

Structures and thermal expansion properties of Lu_2-xFe_xMo₃O₁₂ have been investigated by X-ray diffraction (XRD). XRD patterns at room temperature indicate that compounds Lu_2-xFe_xMo₃O₁₂ with x≤ 1.3 exhibit orthorhombic structure with space group Pnca; compounds with x=1.5 and 1.7 have 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 Lu_1.3Fe_0.7Mo₃O₁₂ in the temperature range of 200-400 ℃.