| 摘要 |
PURPOSE:To directly synthesize alpha-iron oxide having a low axis ratio and useful for magnetic recording, etc., by properly blending a ferric salt with citric acid and alkaline compound, adjusting the pH of the resultant aqueous slurry and heating the adjusted slurry at a specific temperature. CONSTITUTION:An aqueous solution of an alkaline compound, e.g. NaOH, etc., is added to an aqueous solution prepared by dissolving a ferric salt, e.g. FeCl3 and citric acid or a salt thereof in an amount of 0.001-0.1mol based on 1g atom iron is added to the solution and stirred. The pH of the resultant aqueous slurry containing the three components is adjusted to <=10 using NaOH, etc., and the adjusted slurry is then heated to >=120 deg.C. The heated slurry is further cooled to take out precipitates, which are washed and dried. According to this method, the aimed rice granular alpha-iron oxide having <=0.3mum major axis is obtained. The iron oxide is useful as a precursor for magnetic powder or pigment. |
