| 摘要 |
PURPOSE:To obtain a medium suppressing demagnetization by cooling and having superior shelf stability and high density recording characteristics by specifying the compsn. of hexagonal barium ferrite powder in a magnetic layer and incorporating a specified amt. of nonmagnetic powder having a specified hardness or above into the ferrite powder. CONSTITUTION:A compsn. represented by a formula Ba0.n[Fe2-(a+b+c+d)Coa-a NibZncTid03+e] (where n=5.5-6.0, each of a-d=0.01-0.2, (a+b+c)/d=1-10 and e=-0.3-0.01) is provided to hexagonal barium ferrite powder in a magnetic layer and 1-30wt.% nonmagnetic powder having >=7 Moh's hardness is incorporated into the ferrite powder. When Al2O3 powder is used as the nonmagnetic powder, the amt. of Al is regulated to 0.7-21.6wt.% of the amt. of Fe in the ferrite powder. The temp. dependency of the coercive force of the magnetic layer is reduced and a medium suppressing demagnetization by cooling and having superior shelf stability and high density recording characteristics is obtd. |
