PURPOSE: To obtain a magnetic powder whose particle size and shape distribution are controlled easily in order to improve a short-wavelength S/N characteristic which has not been realised easily in a spinel-type ferrite-coated hexagonal- system ferrite in conventional cases in the magnetic powder which is used for a magnetic recording medium.
CONSTITUTION: A magnetic powder is prepared in such a way that a spinel-type ferrite and a fine crystal particle of α-iron are applied to at least a part on the surface of a hexagonal M-type magnetoplumbite ferrite powder. In the preparation method of the magnetic powder, a divalent iron salt is used as raw materials for the spinel-type ferrite and the α-iron, divalent iron is coprecipitated or an oxidizing reaction and a reducing reaction are generated simultaneously under a proper oxygen amount, and the α-iron and the spinel-type ferrite are precipitated simultaneously.
KUBO OSAMU
OGAWA ETSUJI
NOMURA TSUTOMU
MAEDA TATSUMI
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