| 摘要 |
PURPOSE:To obtain the titled ferromagnetic non-acicular particles having an appropriate mean particle size by composing the surface of the particle of fine BaO.n{(Fe1-aRa)2O3} corpuscle powder modified with spinel ferrite. CONSTITUTION:Fine plate Ba ferrite corpuscle powder consisting of fine plate BaO.n{(Fe1-aRa)2O3} [where 4<=n<=6, 0<a<=0.2, and R is Co(II), Ti(IV), or a bivalent metallic ion other than Co(II)] corpuscle powder whose surfaces are modified with spinel ferrite (M<2+>xFe<2+>yO.Fe2O3, where 0<x<=1, 0<=y<1, and 0<x+y<=1, and M<2+> is one or >=2 kinds selected from Ni, Mn, Zn, Cu, and Mg), fine plate BaO.n{(Fe1-aRa)2O3} corpuscle powder, and an alkaline suspension at 8.0-14.0pH contg. 0.1-30.0atom%, based on the sum total of Fe(III) and R in the fine plate BaO.n{(Fe1-aRa)2O3} corpuscle powder, M<2+> or M<2+> and Fe<2+> are mixed. The mixture is heated at 50-100 deg.C. Consequently, the fine BaO.n{(Fe1-aRa)2O3} corpuscle power having 0.05-0.3mum mean particle diameter can be obtained, and the fine particles are appropriately used especially as the magnetic material for vertical magnetic recording.
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