Synthesis and structural characterization of YVO3 prepared by sol-gel acrylamide polymerization and solid state reaction methods

The formation of the YVO3 compound obtained by sol-gel acrylamide polymerization is reported. This synthesis method is contrasted with solid state reaction. Differential thermal analysis (DTA) results show the formation of YVO3 at 805 degrees C compared with 1312 degrees C for solid state reaction. Thermogravimetric analysis (TG) results show that between 400 and 600 degrees C the denaturalization of the organic part, ethylenediamine, and the decomposition of nitrates occur. The evolution of YVO4 into YVO3 was also studied by X-ray powder diffraction (XRD). The refinement results obtained for both YVO3 samples show an orthorhombic phase with Pbnm (62) space group and lattice parameters: a = 5.283 angstrom, b = 5.605 angstrom and c = 7.580 angstrom. Grain size and morphology evolution for different heat treatments were studied with scanning electron microscopy (SEM). The use of sol-gel acrylamide synthesis allows us to start with a homogeneous grain distribution with a mean size of 5.03 +/- 0.65 nm growing up to 4.11 +/- 0.87 mu m in YVO4. After reduction to YVO3 the final grain size was 2.87 +/- 0.10 mu m also with grain size homogeneity. This is in contrast with samples prepared by solid state reaction for which the grain size starts (YVO4) between 1 and 7.0 mu m and ends (YVO3) with a size distribution centered at 90.32 +/- 74.46 mu m. Transmission electron microscopy (TEM) results corroborate XRD results. Energy dispersive X-ray (EDX) results are in agreement with theoretical values.