Sol-gel derived cobalt containing Ni–Zn ferrite nanoparticles: Dielectric relaxation and enhanced magnetic property study

A systematic study of transitional metal ion doped nickel-zinc ferrite (NZF) nanoparticles with its magnetic properties and conductivity relaxation mechanism are the objectives of this research. We have prepared cobalt doped NZF nanoparticles (NZCo) via a facile chemical route. X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) analyses suggest the formation of single phase nearly spherical nanoparticles around 60 nm in size. UV–Vis study reveals the redshift of the optical band gap for doped samples. Estimation of particle size using the effective mass model agrees well with TEM/XRD results. The electrical modulus spectra have been analyzed using Harvilliak-Negami model function. Migration energy has been found to be the minimum for 10 mol % doped sample. Frequency-dependent modulus spectra have been converted to time domain data and the relaxation process shows Kohlrausch–Williams–Watts (KWW) type behavior. Carrier motion inside the lattice has been found to be strongly correlated. Room temperature magnetization curve shows that very weak AFM/PM contribution and strong FM interaction inside the system as well as non-collinear spin arrangements between interstitial sites. Law of Approach (L.A.) analysis of the AFM/PM part subtracted hysteresis curve delineates the enhanced magnetic properties such as saturation magnetization, anisotropy constant and coercivity. Multi-functional materials of such kind with optimum behavior at specific doping percentages can be fruitful for electronic industries.