Ishihara Sangyo Kaisha, Ltd.

Kiyoshi Asano

Tokuo Suita

Kazuo Nakata

Masatsuyo Maruo

Arata Koyama

Nobusuke Takumi

Shigeru Takatori

Kouichi Tamura

Cobalt-containing magnetic iron oxide particles extremely suitable for magnetic recording mediums, especially for image recording mediums and a process for producing the same from the precursor, .gamma.-FeOOH which is advantageous in industry are disclosed. Cobalt-containing magnetic iron oxide particles satisfying the following equations (1), (2) and (3):

Cobalt-containing magnetic iron oxide and process for producing the same

A process for producing a magnetic powder which comprises coating the particle surfaces of a magnetic iron oxide with a cobalt compound or a cobalt compound and a ferrous compound and further coating with a compound of at least one metal selected from the group consisting of manganese, vanadium and zinc. There is obtained a magnetic powder having high coercivity and excellent dispersibility in organic binders. This magnetic powder is useful as a material for recording media such as magnetic tapes.

Process for producing magnetic powder and product

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Yokkaichi, Japan

Kiyoshi Asano