| 摘要 |
PURPOSE:To obtain magnetic powder for high-density recording by using minute particles which contain prescribed metal elements MI, MII and MIII and are expressed by a general formula FeaCobTicMIdMIIeMIIIrOg. CONSTITUTION:MI denotes Ba, Sr, Ca or Pb, MII La, Ce, Nd or Sm, and MIII Si, Ge, Sn, Sb, Mo, W, V, Ni, Cu, Zr, P, Te, Bi, Cd or Ag. At least one kind of element is selected from each of MI, MII and MIII, and as for the number of atoms, (a) is selected to be 8-11.8, (b) and (c) to be 0.05-0.2, (d) to be 0.5-3.0, (e) and (f) to be 0.001-3.0, and (g) to be the number of atoms of 0 satisfying the valence of other elements. An ionic water solution of these metals and an alkaline water solution are mixed to prepare a coprecipitation substance, and this is washed with water, dried and baked at high temperature, so as to obtain magnetic powder of ferrite of a hexagonal system having an average particle size of 0.01-0.3 mum. This constitution enables the attainment of magnetic powder which has little nonuniformity in the average particle size and coercive force saturation magnetization and is suitable for a high-density magnetic recording medium. |
