Preparation of NiAl2O4/SiO2 and Co2+‐Doped NiAl2O4/SiO2 Nanocomposites by the Sol–Gel Route

Abstract

NiAl2O4/SiO2 and Co2+‐doped NiAl2O4/SiO2 nanocomposite materials of compositions 5% NiO – 6% Al2O3– 89% SiO2 and 0.2% CoO – 4.8% NiO – 6% Al2O3– 89% SiO2, respectively, were prepared by a sol–gel process. NiAl2O4 and cobalt‐doped NiAl2O4 nanocrystals were grown in a SiO2 amorphous matrix at around 1073 K by heating the dried gels from 333 to 1173 K at the rate of 1 K/min. The formations of NiAl2O4 and cobalt‐doped NiAl2O4 nanocrystals in SiO2 amorphous matrix were confirmed through X‐ray powder diffraction, Fourier transform infrared spectroscopy, differential scanning calorimeter, transmission electron microscopy (TEM), and optical absorption spectroscopy techniques. The TEM images revealed the uniform distribution of NiAl2O4 and cobalt‐doped NiAl2O4 nanocrystals in the amorphous SiO2 matrix and the size was found to be ∼5–8 nm.