Facile and Low-Temperature Synthesis of Scandium Molybdate for Thermal Expansion Control

Sc2Mo3O12 was successfully synthesized via a facile co-precipitation reaction by scandium nitrate and ammonium molybdate solution followed by a heat-treatment process at 200 ℃. Phase evolution, microstructure and morphology of the Sc2Mo3O12 sample were investigated using TG-DSC, XRD, Raman, TEM, and SEM. High-temperature XRD was used to investigate the change of the lattice parameters of the Sc2Mo3O12 sample as the temperature rise and characterize its negative thermal expansion (NTE) property. Results indicate that well-crystallized flaky Sc2Mo3O12 with an orthorhombic structure can be synthesized by co-precipitation reaction following by an annealing at the temperature as low as 200 °C. The obtained flaky Sc2Mo3O12 sample exhibits anisotropic NTE. The coefficients of thermal expansion (CTE) are -6.28×10-6, 5.53×10-6 and -4.28×10-6 °C-1 along the a-, b- and c- axis directions, respectively. The corresponding volumetric CTE (αv) is -5.05×10-6 °C-1 in 25-700 °C.