Abstract
An experiment was carried out to investigate the effect of Mn substitution on Co-Ni spinel ferrite prepared by the chemical coprecititation method without post-annealing. The chemical coprecipitation compositions were chosen according to the formula (CoO)0.5(NiO)0.5-y(MnO)y·n/2(Fe2O3), where y varied between 0 and 0.5 and n between 2.0 and 2.5. Optimum magnetic properties were achieved with materials whose composition was (CoO)0.5(NiO)0.4(MnO)0.1·1.125(Fe2O3). The typical magnetic and physical properties are saturation magnetization σs = 55.5 × 10-6 Wb·m/kg (44.2 emu/g), coercivity HcJ = 567.2 kA/m (7.12 kOe), average particle size D = 43 nm, anisotropy constant K1 = +1.36 × 105 J/m3 (+1.36 × 106 erg/cm3), K2 = −11.3 × 105 J/m3 (−11.3 × 106 erg/cm3), anisotropy field HA ≈ 3.56 MA/m (44.7 kOe). The rotational hysteresis integral Rh, which is related to the magnetization mechanism of these fine particles, is 1.62, and it was found that the magnetization mechanism is an incoherent one.
