Low loss nickel doped magnesium–manganese ferrite nanoparticles: A study of structural and magnetic properties

Nickel doped magnesium-manganese spinel ferrites with nominal composition Mg0.5Mn0.5Fe2-xNixO4 (x ​= ​0.0, 0.15, 0.20, 0.25) nanoparticles are synthesized using WOWS sol gel method. Initially, the mixture is heated along with continuous stirring to dissolve all precursors and then, precursors’ mixture is converted it into gel, and finally a fluffy powder is obtained. Powder and some prepared pellets of all samples are annealed at 700 ​°C in a furnace for 1 ​h. The x-ray diffraction (XRD) spectra revealed that all samples are of single-phase spinal crystal structure and possess a good crystallinity. The crystallite size obtained from XRD data decreases with the increase in doping concentration. The lattice parameter has values from 8.35 to 8.38 ​Å. Surface morphology observed by scanning electron micrographs (SEM) reveals that most of the particles are of almost spherical shape and size distribution of the particles varies in the range of 71–84 ​nm. Dielectric constant and dissipation factor decreases sharply at low frequencies and becomes almost constant at higher frequencies. Dielectric constant and dissipation factor decreases from 8.82 to 1 and 0.18 to 0.01 respectively with the increase in doping concentration. Results obtained from vibrating sample magnetometer (VSM), reveals the increasing trend in both saturation magnetization and coercivity with the increase in nickel concentration. The synthesized material could find its application data storing cards and magnetic recording media.