| abstract |
To provide hexagonal ferrite magnetic particles suitable as a ferromagnetic material in a magnetic recording medium for high-density recording. A raw material mixture containing Al is melted, the obtained melt is rapidly cooled to obtain an amorphous body, and hexagonal ferrite magnetic particles are precipitated by heat-treating the amorphous body. Further, by subjecting the substance obtained by the heat treatment to acid treatment and washing treatment, the Al content with respect to the total amount of particles is Al 2 O with a particle size in the range of 15 to 30 nm and Al deposited on the surface. Collecting hexagonal ferrite magnetic particles that are 0.6 to 8.0% by mass in terms of 3 ; [Selection figure] None |