METHOD FOR PRODUCING HEXAGONAL FERRITE MAGNETIC POWDER, AND MAGNETIC RECORDING MEDIUM AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a hexagonal ferrite magnetic powder achieving ultrahigh density recording, and a magnetic recording medium using the hexagonal ferrite magnetic powder and suitable for high density recording.

SOLUTION: A method for producing such a hexagonal ferrite magnetic powder includes: melting a raw material mixture containing glass-forming components containing a B2O3component and hexagonal ferrite-forming components, and containing the B2O3component in an amount of 15-27 mol% in terms of B2O3to form a melt; rapidly cooling the melt to form a solidified product having a saturation magnetization of ≤0.6 A×m2/kg; and depositing a hexagonal ferrite magnetic powder having an average plate diameter of 15-25 nm by heating the solidified product to a temperature range of 600-690°C and keeping it in the temperature range. The magnetic recording medium has a magnetic layer containing a hexagonal ferrite magnetic powder produced by the method and a binder on a nonmagnetic support. A method for producing such a magnetic recording medium includes the method.

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