Effect of Sm3+ substitution on dc electrical resistivity and magnetic properties of Ni–Co ferrites

Sm3+ substituted Ni–Co ferrite materials have been developed with the chemical compositions Ni0.5Co0.5Fe2-xSmxO4 for x = 0.0, 0.02, 0.04, and 0.06 by solid-state method. A spinel with a single-phase cubic structure was found through XRD analysis. Crystallite size and lattice parameter fluctuation with Samarium content, decreasing with Sm3+ doping. When Sm3+ is doped, SEM shows a uniform distribution of grains with increasing agglomeration, and the grain size decreases with samarium concentration. Two peaks of absorption mode FTIR spectra show their spinel nature. The samples' negative temperature coefficient measured by the two probe method indicates their semiconducting nature. The DC electrical resistivity of the Ni–Co ferrite system was found to increase from 5.99 × 103 (Ω-cm) to 9.89 × 109 (Ω-cm) as an increase in Sm concentration. VSM measurement gives the saturation magnetization for the concentration up to x = 0.04 decreased and then increased for x = 0.06. All these properties show our samples' higher applicability in various electronic devices.