Effect of Ni doping on structural and magnetic properties of Co1-xNixFe1.9Mn0.1O4

Nickel-substituted iron-deficient cobalt ferrite containing small quantity of manganese having the chemical composition Co_1−xNi_xFe_1.9Mn_0.1O₄ with x=0.2, 0.4, 0.6 and 0.8, were prepared by the standard double sintering ceramic technique. The thermal decomposition process of the powder (i.e. grounded starting materials) was studied by thermo-gravimetric analysis (TGA). The compositional analysis was carried out by EDAX pattern. The infrared spectroscopy studies show the presence of tetrahedral and octahedral group complexes within the spinel phase. Microstructural features were studied by scanning electron microscopy, grain size found to be decreasing with increasing Ni content. Room temperature hysteresis measurement was carried out under the field of 6 kOe for all samples which reveal monotonic decrease of magnetization at 6 kOe (M_6 kOe). The coercive field (H_c) decreases up to concentration of Ni²⁺ (x=0.6) and a small increase was observed for x=0.8. Initial permeability (μ_i) plotted against temperature at 10 kHz shown sharp drop at Curie temperature and values observed at transition are found to be dependent on the nickel content.