化学的共沈法による高保磁力Coスピネルフェライト微粒子の磁気特性

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The experiment was carried out to investigate the effect of changing mole ratio, n (= Fe^<3+>/Co^<2+>), and pH conditions on magnetic and physical properties of Co ferrite prepared by the chemical coprecipitation method without post-annealing. The chemical coprecipitation compositions were chosen according to the formula (CoO)-n/2(Fe_2O_3), where n varied between 2.0 and 3.5. Optimum magnetic properties were achieved with materials of composition (CoO) ・ 1.375(Fe_2O_3). The typical magnetic and physical properties are saturation magnetization σ_s = 61.6×10^<-6> Wb ・ m/kg (49.0 emu/g), coercivity H_<cJ> = 255 kA/m (3.21 kOe), lattice constant a = 0.8391 nm, and average particle size D = 23 nm, anisotropy constant K_1 = +2.7 × 10^4 J/m^3 (+2.7 × 10^5 erg/cm^3), K2 = -13.0×10^4 J/m^3 (-13.0×10^5 erg/cm^3), anisotropy field H_A ≒ 3 MA/m (37.7 kOe). The rotational hysteresis integral Rh, which is related to the magnetization mechanism of these fine particles, is 1.32, and it was found that the magnetization mechanism is an incoherent one.
2004-02-01