研究
化学的共沈法によるCo-Ni-La系スピネルフェライト微粒子の磁気特性
2009 年 56 巻 3 号 p. 137-144
詳細
2009 年 56 巻 3 号 p. 137-144
An experiment was carried out to investigate the effect of La2O3 substitution, molar ratio n {=Fe3+/(Co2++Ni2++La3+)}, concentration of alkali, inflowed time of alkali on the magnetic and physical properties of Co-Ni-La system spinel ferrite fine particles prepared by the chemical coprecipitation method without post-annealing. The chemical coprecipitation compositions were chosen according to the formula (CoO)0.5(NiO)0.5-x(La2O3)0.5x·n/2(Fe2O3), where x varied between 0 and 0.3 and n varied between 2.00 and 2.75. The typical magnetic properties were saturation magnetization σs=47.5×10-6 Wb·m/kg, residual magnetization σr=25.3×10-6 Wb·m/kg, coercivity HcJ =666.1 kA/m. To remove the superparamagnetic substance, the coprecipitation fine particles were etchied with dilute sulfuric acid. As a result, in the (CoO)0.5(NiO)0.475(La2O3)0.0125·1.25(Fe2O3) composition, when the excess NaOH and inflowed time were 0.9 mol and 1 s respectively, the following magnetic and physical properties were obtained: σs=75.9×10-6 Wb·m/kg, σr=58.1×10-6 Wb·m/kg, HcJ=1004.3 kA/m, K1=1.96×105 J/m3, K2=−6.4×105 J/m3, and HA=4.00 MA/m.
