Cationic distribution of nickel doped NixCoX-1Fe2O4 nanparticles prepared by hydrothermal approach: Effect of doping on dielectric properties

Abstract This research work focusses on the doping of nickel in cobalt ferrites to enhance their dielectric and electrical properties. NixCoX-1Fe2O4 nanoparticles (NPs) with doping ratios x=0, 0.1, 0.2, 0.3, 0.4 and 0.5 are synthesized using hydrothermal method. The effect of doping is studied using XRD, FTIR, Raman spectroscopy and Impedance Analyzer. The formation of cobalt ferrites NPs is confirmed by matching the samples with the standard data (JCPDS card no 22-1086). The crystallite size of NixCoX-1 Fe2O4 NPs lies in the range of 14.64-19.81 nm. Cationic distribution analysis suggested that doping leads to small deviation in their angles due to differences in the ionic radii of Co (0.74A) and Ni (0.69 A). This analysis shows that lattice constant, density, dislocation density, radii of tetrahedral and octahedral sites and oxygen position changes with the increase of concentration of Ni2+ in cobalt ferrites. FTIR shows the two prominent vibrational bands in range 550-610 cm-1 and 400-450 cm-1. The two most intense optical band gap energies were observed with Raman spectroscopy technique at Eg and T2g values that increases with increasing Ni2+ concentration. It was observed that dielectric properties enhanced spectacularly with doping. The dielectric constant and loss tangent decreased at high frequencies. On the other hand, increase in AC conductivity was observed with increasing frequency.