Exploration of properties (crystallographic, morphological, optical) of nano cobalt aluminate synthesized by facile sol-gel method: Effects of sintering temperature

The present work reports on the facile sol-gel synthesis of CoAl2O4 nanoparticles using cobalt nitrate and aluminum nitrate as the metal salts and citric acid and glycerol as chelating agents. The consequence of sintering temperature on the structure, particle size, morphology, composition, zeta potential, color, and reflectance spectra at neutral pH condition were explored with various instrumental techniques. The CoAl2O4 nanoparticles were characterized with Powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FESEM), Energy dispersive spectroscopy (EDS), Nanoparticle size analyzer, Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis-DRS) and CIE-Lab colorimetric method. From the data of PXRD, the crystallite size and peak profile analysis were investigated by four different models. It was found that the average crystallite size varied in the range of 28.01-320.97 nm and single-phase cubic CoAl2O4 was formed without any impurity. The average particle size of CoAl2O4 nanoparticles was discerned from the FESEM images using ImageJ software and from a nanoparticle size analyzer. The average particle sizes were increased with the increasing sintering temperature. The values of zeta potential found in all of the samples represented high dispersion stability. From the colorimetry of CoAl2O4 nanoparticles, the CIE-La*b* output illustrated high purity and brightness and the spectra.