METHOD FOR PRODUCING FERROMAGNETIC METAL POWDER

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PROBLEM TO BE SOLVED : To produce metal magnetic powder capable of obtaining a high density magnetic recording medium having satisfactory preservation stability and magnetic properties.SOLUTION : Through a stage where Al-containing iron oxyhydroxide is heated at 250 to 400°C to fix Al as Al2O3, then, a rare earth element (inclusive of Y) is incorporated therein, and the obtained powder of iron oxide comprising Al and a rare earth element (inclusive of Y) is heated and reduced in a reducing atmosphere, and a stage where water washing is performed before the incorporation of a rare earth element (inclusive Y) and after the fixing of Al as Al2O3, the acicular ferromagnetic metal powder in which the content of the group 1a elements in the Periodic Table is ≤0.05 wt.%, and, if required, aluminum of 0.1 to 30 atomic% to the total content of the metal elements, and further, a rare earth element (inclusive of Y) of 0.1 to 10 atomic% to the total content of the metal elements are incorporated, and also, the residual amount of the group 2a elements in the Periodic Table to be made soluble is ≤0.1 wt.% is obtained.COPYRIGHT : (C)2006, JPO&NCIPI