Synthesis and thermal expansion properties of Y2-xLaxMo3O12 (x=0, 0.5, 2)

Y2-xLaxMo3O12 (x=0, 0.5, 2) ceramics were successfully synthesized by the solid state reaction method. The microstructure, composition and thermal expansion property of the resulting samples were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and dilatometry. Results indicate that the Y1.5L0.5Mo3O12 crystallizes in monoclinic Tb2Mo3O12-type structure and it is non-hygroscopic. The Y1.5La0.5Mo3O12 ceramic is denser than the Y2Mo3O12 and La2Mo3O12 ceramics, and its relative density can reach 94.12% of the theoretical value. Most importantly, it shows almost zero thermal expansion and its thermal coefficient is 0.87 x 10(-6) K-1 from 178 degrees C to 600 degrees C. Y2Mo3O12 ceramic shows negative thermal expansion whereas La2Mo3O12 ceramic shows positive thermal expansion, their thermal expansion coefficients being-12.06 x 10(-6) K-1 and 8.88 x 10(-6) x 10(-6) K-1, respectively. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.