Frequency dependence of electrical and magnetic properties of Li–Ni–Mn–Co ferrites

Substituted Li-ferrites with compositional formula Li0.45−x/2Ni0.1Mn0.1CoxFe2.35−x/2O4 with x ranging from 0 to 0.1 in steps of 0.02 were prepared by the conventional ceramic technique. The single-phase spinel structure of the samples was confirmed by XRD analysis. The lattice constant was observed to increase with the increase of the Co2+ substitution. The dielectric constant, ε ′ and dielectric loss tangent, tan δ was studied as a function of frequency in the range 100 Hz to 1 MHz. A decrease is observed in the value of ε ′ with substitution at lower frequencies. ε ′ showed a dispersive behavior with frequency for all the samples. The frequency dependence of tan δ showed a resonance peak. The magnetic properties viz initial permeability and magnetic loss were also studied as a function of frequency. The possible mechanisms contributing to the results have been discussed.