| 摘要 |
PURPOSE:Specific amounts of an alkali hydroxide and a silicate salt are added to an aqueous metal salt solution containing specific amounts of Ba and Pe, the mixture is subjected to hydrothermic treatment, NaCl is added, then, roasting is effected at a specific temperature and the product is rinsed to give a barium ferrite powder of high dispersibility and high smoothness. CONSTITUTION:An aqueous metal salt solution containing Ba and Fe at an gram-atom ratio of 1/(5-11) is heated up to about 50-130 deg.C and an alkali hydroxide such as sodium or potassium hydroxide is added in such an amount as it exceeds the neutralization equivalent so that the concentration of the alkali becomes more than 3mol/l. Further, a silicate salt is added to the aqueous solution so that Si becomes 0.01-5atom% based on the Fe in the solution. The resultant slurry is subjected to hydrothermic treatment by keeping it at 130-270 deg.C to form fine crystals of barium ferrite and allow them to precipitate. The precipitate is separated, rinsed with water, combined with 10-80wt% of NaCl and/or BaCl and roasted at 650-950 deg.C, washed and dried. Thus, a magnetoplumbite type of hexagonal barium ferrite powder is obtained. |
