MAGNETIC METAL POWDER FOR MAGNETIC RECORDING MEDIUM

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PROBLEM TO BE SOLVED : To provide metal magnetic powder suitable for a coating-type magnetic recording medium of high recording density where saturation magnetization σs is large considering a particle volume while maintaining a weather resistance level equivalent to a prior art. SOLUTION : The metal magnetic powder for the magnetic recording medium includes a particle having a metal magnetic phase composed mainly of Fe or Fe/Co and an oxide film where the average major axis length of the powder particle is 10-50 nm, the average particle volume including the oxide film is 5, 000 nm3 or smaller, and an atomic ratio (R+Al+Si)/(Fe+Co) calculated using the content (atom%) of an element contained in the powder particle is 20% or smaller where R is a rare earth element (Y is treated as a rare earth element). The metal magnetic powder is obtained by using a complexing agent and a reducing agent to elute nonmagnetic constituents after firing. COPYRIGHT : (C)2011, JPO&INPIT