| 摘要 |
PURPOSE:To obtain superior magnetic characteristics by beforehand adding a prescribed amount of Mg salt and reducing the resultant particles within a prescribed temp. range at the time of oxidizing a suspension of Fe(OH)2 obtained by neutralization to form alpha-FeOOH particles. CONSTITUTION:An alkali is added to an aqueous ferrous salt soln. to form a suspension of >=11pH contg. Fe(OH)2. Then, magnesium salt is added at 0.5- 20atom% expressed in terms of Mg with respect to Fe to this suspension. Thence, it is permeated with an oxygen contg. gas and is oxidized, whereby needle crystal alpha-FeOOH is obtained. This needle crystals has 0.3-20mum long axes, and >=20:1 axial ratio in average values, and this is reduced by heating at 300-450 deg.C in a reducing gas, whereby Fe-Mg alloy magnetic particles of needle crystal are obtained. |
