Influence of Ni over magnetically benign Co ferrite system and study of its structural, optical, and magnetic behaviour

Nickel-substituted cobalt ferrite nanoparticles (NixCo1-xFe2O4, where x = 0.0 to 1.0 with a step size of 0.2) were synthesized using a citrate precursor process and characterized using Scanning Electron Microscopy (SEM), Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-Ray diffraction (XRD) and vibrating sample magnetometry (VSM). XRD confirmed the formation of cubic spinel ferrite nanoparticles for all the samples without any impurity phase. The crystallite size is observed to vary between 39.78 nm and 41.11 nm, whereas the lattice parameters are observed to decrease from 8.369 angstrom to 8.333 angstrom with the increase in Ni doping. In the FTIR spectra, two characteristic bands were observed at the octa and tetrahedral sublattices. From the Raman spectra, five Raman active modes (2A1g + Eg + 2T2g) were observed and an inverse (cubic) spinel structure of Ni-Co ferrite nanoparticles was established. The hysteresis curve of NixCo1-xFe2O4 shows the extremely magnetic nature of the nanoparticles whose saturation magnetization, remanence magnetization, and coercivity decrease with nickel doping. The saturation magnetization value (sigma s) is observed to decrease from 70.18 emu/g to 43.16 emu/g, whereas, the value of coercivity decreases from 2.27 kOe to 0.51 kOe with the increase in Ni doping concentration. The magnetic properties indicate that the prepared nanoparticles can be used for data storage device applications.