Effects of reaction temperature and raw material type on optical properties and crystal phase growth of Solid state synthesized NiSb2O6 nanomaterials

Nanostructured NiSb2O6 samples were synthesized via solid state reactions at the reaction temperatures of 600, 700 and 800 °C using Sb2O3, Ni(CH3COO)2.2H2O and Ni(NO3)2.6H2O as raw materials. Parameters of reaction temperature and raw materials types were investigated for the crystal phase growth study. The synthesized nanomaterials were characterized by X-ray powder diffraction (XRPD) technique, fourier-transform infrared (FTIR) spectroscopy. Brunauer–Emmett–Teller (BET) and Barrett-Joyner-Halenda (BJH) methods were used to investigate the textural properties of the obtained samples. Rietveld analyses showed that the obtained materials were crystallized well in the tetragonal crystal structure with the space group of P42/mnm. The lattice parameters of the targets were about a = b = 4.64 Å and c = 9.22 Å. The data revealed that the crystal phase purity of the as-synthesized nanomaterials was increased with increasing the reaction temperature from 600 to 800 °C. Besides, the data indicated that the synthesis reactions using Ni(NO3)2.6H2O generated a better crystalline growth and purity compared to Ni(CH3COO)2.2H2O raw material in a certain reaction temperature. The morphologies of the synthesized materials were studied by field emission scanning electron microscopy (FESEM) technique. The FESEM images showed that the homogeneity of the synthesized powder was improved when Ni(NO3)2.6H2O was used as raw material. Ultraviolet-visible spectra showed that the synthesized NiSb2O6 nanomaterials had strong light absorption in the ultraviolet light region. The calculated direct optical band gaps tendency showed that the band gaps were increased with increasing the reaction temperature.