| 简介 |
PROBLEM TO BE SOLVED : To provide a hexagonal ferrite magnetic powder which has a high magnetic property, while having a small-particle volume and a high specific surface area; and a high-density magnetic recording medium prepared by using the hexagonal ferrite magnetic powder.
SOLUTION : The hexagonal ferrite magnetic powder is formed by using a glass crystallization method and is produced by a method comprising a process for mixing raw materials including a glass base material, iron, bismuth, a bivalent metal (M1), a tetravalent metal (M2), one kind (A) selected from among barium, strontium, calcium and lead, and at least one kind (R) of rare-earth element in a content equimolar to or lower than iron; a process for forming a glass body by heating the mixed raw materials; a process for rapidly cooling, then crushing and heat-treating the glass body; and a process for cleansing the glass body after heat treatment with an acid solution.
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