| 摘要 |
PURPOSE:To produce the subject magnetic powder having high saturation magnetization, small particle diameter and small flatness by synthesizing a coprecipitated raw material powder containing a spinel crystal phase from an aqueous solution containing Ba<2+> ion, a specific amount of Fe<3+> ion and a specific bivalent metal ion and calcining the raw material powder. CONSTITUTION:Ultrafine raw material powder containing a spinel crystal phase is produced by reacting (A) an aqueous solution containing Ba<2+> ion, >=12mol (based on 1mol of Ba<2+> ion) of Fe<3+> ion, one or more bivalent metal ions forming a spinel crystal structure (e.g., Fe<2+> ion, Co<2+> ion, Zn<2+> ion, Cu<2+> ion and Ni<2+> ion) and other metal ion with (B) an alkaline aqueous solution (e.g., NaOH solution). The raw material powder is calcined in a non-oxidizing atmosphere at 600-700 deg.C. Magnetic powder having high saturation magnetization, small particle size and small flatness can be produced by the above process. A magnetic recording medium having improved S/N ratio can be produced by packing the particles in high density. |
