Influence of Cr³⁺ substituted NiZnCo nano-ferrites: structural, magnetic and DC electrical resistivity properties

This report synthesized the Cr3+-substituted NiZnCo ferrite nanoparticles using the sol–gel auto-combustion method. The X-ray diffraction (XRD) pattern revealed the formation of single-phase spinel cubic ferrite. The lattice constant is observed to increase from 8.34 Å to 8.47 Å for x = 0.05 and further decreases to 8.38 Å with the further increase in doping, whereas crystallite size decreases from 32.15 nm to 25.68 nm. Field Emission Scanning Electron Microscopy (FESEM) shows that grain size increases initially with Cr3+ concentration, whereas for x = 0.2, grain size decreases. Fourier Transform Infrared Spectroscopy (FTIR) shows the formation of peak v1 around 600 cm−1 and v2 around 400 cm−1, confirming the formation of spinel structure. The reducing saturation magnetization from 68.49 emu/g to 51.64 emu/g with the addition of Cr3+ ions shows a higher B–B interaction than A–B interaction. The DC resistivity increased with the increase in dopant concentration till x = 0.1, and with further increase in doping concentration, the resistivity decreased.