Synthesis and tunable thermal expansion properties of Sc2−xYxW3O12 solid solutions

A new series of rare earth solid solutions Sc2−xYxW3O12 was successfully synthesized by the conventional solid-state method. Effects of doping ion yttrium on the crystal structure, morphology and thermal expansion property of as-prepared Sc2−xYxW3O12 ceramics were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TG), field emission scanning electron microscope (FE-SEM) and thermal mechanical analyzer (TMA). Results indicate that the obtained Sc2−xYxW3O12 samples with Y doping of 0≤x≤0.5 are in the form of orthorhombic Sc2W3O12-structure and show negative thermal expansion (NTE) from room temperature to 600 °C; while as-synthesized materials with Y doping of 1.5≤x≤2 take hygroscopic Y2W3O12·nH2O-structure at room temperature and exhibit NTE only after losing water molecules. It is suggested that the obvious difference in crystal structure leads to different thermal expansion behaviors in Sc2−xYxW3O12. Thus it is proposed that thermal expansion properties of Sc2−xYxW3O12 can be adjusted by the employment of Y dopant; the obtained Sc1.5Y0.5W3O12 ceramic shows almost zero thermal expansion and its average linear thermal expansion coefficient is −0.00683×10−6 °C−1 in the 25–250 °C range.