| 摘要 |
PURPOSE:To have fine and uniform grain diameter and obtain a useful hexagonal plate-like barium ferrite fine powder superior in diffusion as a magnetic powder for a vertical magnetic recording medium by holding magnetite substituted by at least Ba for a portion of Fe at specific temperature in a high boiling point organic solvent. CONSTITUTION:Magnetite in which a portion of Fe is substituted by at least Ba can be produced by an arbitrary method, but for example, iron (II) compound and barium compound, namely, alkali is added to solution in which Co, Mn, Ti and other base metal compounds are dissolved in an organic solvent together with these at room temperature and pressure to produce a suspension of alkaline iron hydroxide (II) and an oxygen containing gas is introduced at a specific temperature in a reaction liquid to preferably oxidize. Thereby, a plate-like barium ferrite fine powder can be produced by holding the reaction liquid at a temperature of 180-280 deg.C as it is. Further, when the magnetite is produced, pH of the reaction liquid is preferably set at 10-13. |
