Effect of Cobalt Substitution on the Magnetic Properties of Ni-Cu Ferrite

Single‐phase polycrystalline Ni0.85−xCu0.15CoxFe2O4 (x = 0, 0.02, 0.04 and 0.06) were synthesized by a standard ceramic technology. The mean particle sizes, obtained by SEM, vary between 2 and 8 μm. The main magnetic parameters such as saturation magnetization, remanence and coercivity were obtained from the entire hysteresis loops plotted in AC (2 kHz) magnetic field at room temperature. Hysteresis losses were evaluated from the same curves by using the Fourier decomposition. The initial permeabilities were obtained from the minor hysteresis loops, plotted in low enough magnetic fields. The remanence decreases almost linear with increasing Co‐concentration. Both saturation magnetization and initial permeability have maxima at x = 0.02, but the coercivity and hysteresis losses have minima at the same Co‐concentration. All the magnetic parameters, obtained at x = 0.02 are better than those of the starting composition with x = 0. The influence of the Co‐substitution on the magnetic parameters is discussed.