Evaluation of Structural,\nMagnetic, and Electromagnetic\nProperties of Co²⁺-Substituted NiCuZn Ferrites

Abstract

We report citrate gel-assisted autocombusted spinel-type\nCo²⁺-substituted NiCuZn ferrites and their electromagnetic\nproperties.\nSeveral complementary techniques were used to investigate the influence\nof Co on structural and electromagnetic properties of Ni_{0.25–<i>x</i>}Co_<i>x</i>Cu_0.20Zn_0.55Fe₂O₄ with <i>x</i> = 0.00–0.25\n(step of 0.05). XRD analysis confirmed the highly crystalline single-phase\ncubic spinel structure with a prominent peak of the (311) plane. FE-SEM\nanalysis showed the loss of porous gel structure (colloidal backbone)\ndue to addition of cobalt into the present ferrite system. The EDAX\nanalysis confirmed the presence of Ni, Cu, Zn, Co, and O in accordance\nwith the relative stoichiometry of Co-substituted NiCuZn ferrite.\nThe electrical resistivity of ferrites is observed to decrease when\nCo²⁺ ions are substituted, regardless of AC and DC. The\ndielectric properties (ε′ and ε″) of ferrites\nexhibited a consistent decrease as the frequency increased, and this\ntrend persisted even at higher frequencies. VSM analysis showed the\nnormal magnetic hysteresis of the developed ferrite system. At <i>x</i> = 0.05, the saturation magnetization of the ferrite was\nobtained to be the highest among the other substitution levels of\nCo. The Curie temperature fell down when there was a higher concentration\nof cobalt in the ferrite system (<i>x</i> = 0.20). After\nreaching a specific temperature, the μ_i values decreased\nabruptly, with an increase in the temperature. The steady state may\nbe deduced from the fact that the constant real component of the initial\npermeability, μ′, remained unchanged. However, with decreasing\nfrequency, the values of μ″ decreased dramatically. The\npresent NiCuZn ferrite series displays the enhanced dielectric properties\nsuggesting the capability of potential candidates for microwave absorption\napplications with enhanced electromagnetic properties.