| 简介 |
PROBLEM TO BE SOLVED : To provide a method for producing a magnetic powder which has a fine particle size by average, and particularly has the magnetic property capable of magnetic-recording data at high density, and to provide a magnetic recording medium.
SOLUTION : This production method comprises the steps of : preparing a reversed micelle solution (I) by mixing a water-insoluble organic solvent containing a surfactant, with an alkaline aqueous solution or the alkaline aqueous solution and an aqueous solution of an oxidizing agent; preparing a reversed micelle solution (II) by mixing a water-insoluble organic solvent containing a surfactant, with an aqueous solution of a compound containing a rare earth element and an aqueous solution of a compound of a transition metal; forming particles made from a hydroxide or oxide of a transition metal containing a rare earth element by mixing the above two reversed micelle solutions; covering the surface of the particles made from the hydroxide or oxide of the transition metal containing the rare earth element, with a layer of a hydroxide of an alkaline earth metal; heating them; reducing them in a gas atmosphere; gradually oxidizing them; and further reducing them with a reduction diffusion method to form the particles with sizes of 5 to 15 nm. The particles may be then nitrided through a nitriding reaction. The magnetic recording medium has a magnetic layer containing the magnetic powder and a binder, on a nonmagnetic support. |
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