Structural and morphology comparison between m-LaVO₄ and LaVO₃ compounds prepared by sol-gel acrylamide polymerization and solid state reaction

We contrast the production of LaVO₃ polycrystalline samples obtained by reduction of m-LaVO₄ prepared by sol-gel acrylamide polymerization (SGAP) and solid state reaction (SSR). For SGAP the formation of m-LaVO₄ occurs at 400 °C, for SSR at 1400 °C. For m-LaVO₄-SGAP we observe a homogeneous morphology with needle-shaped grains of 50 nm average size. The SSR presents a broader size distribution in the micrometer range. Both m-LaVO₄ samples were reduced into LaVO₃ using a Zr rod at 850 °C in vacuum. LaVO₃-SGAP presents a homogeneous grain distribution with an average size of 745 nm. LaVO₃-SSR has an average size of 3.45 μm. The stoichiometry of all compounds was confirmed by energy dispersive X-ray spectroscopy. X-ray powder diffraction and transmission electron microscopy give crystal structures in agreement with those reported in the literature.