BLACK IRON OXIDE PARTICLE

摘要

PROBLEM TO BE SOLVED: To provide aluminum-containing iron oxide particles having a low electrical resistance, containing a large amount of aluminum, being lowly magnetizable, and having a high FeO content and a high degree of blackness. SOLUTION: The black iron oxide particles have a crystal structure mainly of magnetite and contain aluminum. The aluminum is contained in the form of an amorphous compound in the particles. The aluminum content is 3 to 8 wt.%. The lattice constant of the crystal structure is 8.380 to 8.410Å. The particles can be desirably produced by blowing air into an aqueous solution containing ferrous ions and aluminum ions in the presence of an organic acid or a salt thereof to subject it to wet oxidation under conditions that the rate of ferrous ions consumed during the wet oxidation is 4 to 8 g/L per hour. COPYRIGHT: (C)2005,JPO&NCIPI