A Study on Optical and Dielectric Properties of Ni-ZnO nanocomposite

Nickel-zinc oxide (Ni-ZnO) nanoparticles were synthesized via low-cost sol-gel auto combustion route using ethylene glycol as a reducing agent. The structural and surface morphological analysis were confirmed by XRD, FESEM and TEM micrographs which exhibits pure phase formation, unit cell crystal structure and inhomogeneous grain growth in nm range (43.20 nm). The EDXS elemental mappings and SAED patterns exposed the presence of the fundamental element with stoichiometric ratios and double phase formation of Ni-ZnO nanocomposite. The dielectric and conduction mechanism were characterized by impedance, modulus, dielectric and conductance spectra with frequency and temperature evolution. The suppressed Nyquist plot of impedance and modulus with temperature demonstrates the curtailment of grain boundary resistance and dominance of grain contribution. The dielectric constant and loss both lessened with high-frequency evolution and utmost value of dielectric constant 300 was observed at 95 °C. The ion hopping conduction mechanism (Nearest neighbor hopping and Variable range hopping) was proposed to explain its conduction processes and activation energy (1.02 eV) of dc conduction was calculated from Arrhenius plot. Finally, the direct and indirect optical band gap of Ni-ZnO was estimated from UV-DRS absorption spectra using Kubelka-Munk equation.