Improved DC electrical resistivity and magnetic properties of La3+ substituted Ni0·5Co0·5Fe2-xLaxO4 (0.00 ≤ x ≤ 0.20) spinel ferrite systems

In this paper, the impact of La³⁺ substitution on the structural, DC resistivity, and magnetic characteristics of Ni_0·5Co_0·5Fe_2-xLa_xO₄ (where x = 0.0, 0.02, 0.04, and 0.06) prepared using a solid-state approach is reported. XRD analysis shows a single-phase cubic spinel structure with the Fd-3m space group. The lattice constants were computed based on the ionic radii of the constituents and were found to increase rapidly with higher substitution ratios. Crystallite sizes, calculated using the Scherrer formula, ranged between 45.12 and 27.71 nm. SEM images show grains with a homogeneous distribution, exhibiting increased agglomeration as particle size increases with higher concentrations. The FTIR spectra reveal two absorption peaks indicative of the spinel structure. The negative temperature coefficient, obtained using the two-probe method, confirms that the samples are semiconducting materials. The data showed that as the concentration of La³⁺ increased, the DC electrical resistance of the ferrite system also increased. Magnetic measurements indicated that the addition of La³⁺ ions leads to a decrease in coercivity values.