Enhancing the electrical and dielectric properties of ZnO nanoparticles through Fe doping for electric storage applications

Abstract

The present paper provides significant results about the impact of iron doping on the ZnO nanoparticles’ structural and electrical properties. Fe-doped ZnO (ZnO:Fe) nanoparticles with varying doping concentrations from 0 to 5% were effectively synthesized by a simple co-precipitation method. The X-ray diffraction (XRD) studies revealed that all compositions crystallize in the hexagonal wurtzite structure with the P63mc space group. They also proved the presence of a secondary phase accredited to ZnFe2O4 for ZnO:Fe 5% sample. Concerning the transmission electron microscopy, it demonstrated that the formed nanoparticles are spherical. The electrical properties were explored by complex impedance spectroscopy in the 40–107 Hz frequency range and 400–500 K temperature domains. The comparative Nyquist plots at fixed temperature 440 K suggested that the impedance value dropped with the augmentation of Fe doping concentration. Furthermore, the electrical conductivity and dielectric properties were explored as a function of frequency and temperature in the same range. The obtained results demonstrated that iron doping enhanced the AC conductivity at the same selected temperature 440 K. The analysis of the AC conductivity frequency dependence of the ZnO:Fe 1% sample was carried out by Jonscher’s universal power law and the conduction mechanism was interpreted by the overlapping-large polaron tunneling (OLPT) model. Both impedance and modulus analyses were found to display the contribution of grain and grain boundary to the electrical response of the ZnO:Fe 1% sample. Moreover, the dielectric characterization had affirmed that both dielectric constant and dielectric loss decrease with the increase in frequency and increase with the increase in temperature. These two parameters were found to augment with Fe doping. The observed properties had proven that Fe doped ZnO nanoparticles was very functional for the electric storage applications.