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 °C compared with 1312 °C for solid state reaction. Thermogravimetric analysis (TG) results show that between 400 and 600 °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 Å, b = 5.605 Å and c = 7.580 Å. 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 μm in YVO_4. After reduction to YVO₃ the final grain size was 2.87 ± 0.10 μm 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 μm and ends (YVO₃) with a size distribution centered at 90.32 ± 74.46 μm. Transmission electron microscopy (TEM) results corroborate XRD results. Energy dispersive X-ray (EDX) results are in agreement with theoretical values.