Structural and electrical properties of Ni-doped MnZn ferrite synthesized via solid state reaction

Abstract

Abstract MnZn ferrite is commonly studied due to its exceptional magnetic, electric, and catalytic properties, making it a promising material for hyperthermia applications, magnetic fluid, memory storage devices, drug delivery, virus detection, and photocatalysis. It was identified that divalent nickel cation substitution increases the ferrite conductivity and dielectric constant. This study targets to synthesize Ni-doped MnZn ferrite by a simpler, more convenient, and economic solid state reaction, and to investigate its influence on the structural and electrical properties of MnZn ferrite. Mn0.5-xNixZn0.5Fe2O4 (x=0.1 and 0.2) was synthesized via solid state reaction with calcination and sintering temperature at 1000 °C and 1200 °C, respectively. The structural and electrical properties of the resulting pellet were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The XRD profile, indexed as cubic spinel, indicated good crystallinity and no impurity peaks were detected. As Ni2+ dopant concentration increases, a decrease in lattice parameter and an increase in theoretical and apparent densities were observed. This is attributed to the smaller ionic radius and greater mass of Ni2+ relative to Mn2+. Varying Ni2+ concentration significantly modified the morphology of the ferrite. At higher Ni2+, less uniformity in shape and size was evident in the SEM micrograph since Ni promotes aggregation at the surface. An increase in dielectric constant was also observed with increasing Ni2+ molar concentration. Since Ni2+ presents a high tendency to occupy B sites, its substitution promotes Fe2+ migration to A sites, augmenting Fe2+/Fe3+ hopping resulting in an increase in polarization and dielectric constant.