Study of structural, optical and electrical properties of NiO and Fe2O3 (1:1) nanoparticles-composite and compound synthesized by sol-gel method

The NiO/Fe2O3 (1:1) compound and composite nanoparticles were synthesized by a simplified sol-gel method. Samples were calcined at 500 °C/2 h and sintered at 550 °C/1 h inn air. X-ray diffraction confirmed cubic lattice for compound and rhombohedral lattice for composite samples. Scanning electron microscope and Raman spectroscopy were used for surface morphology and structural analysis, respectively. Ultraviolet-Visible Absorption Spectroscopy showed a decrease in the band gap energy values of composite in comparison to the compound. The dc electrical conductivity measurements showed negative temperature coefficient behavior which is explained by hopping mechanism. AC electrical properties were measured in the frequency range of 20 Hz to 3 MHz, at room temperature. The Dielectric Constant as well as Dielectric Loss Tangent values decreased with the increase in frequency values. AC electrical properties are explained using Koop's theory and the Maxwell-Wagner model. Composite samples showed enhanced electrical properties as compared to compound samples.