| 摘要 |
PURPOSE:To obtain magnetic powder suitable for magnetic recording medium for high density recording by bringing a precipitate, which is obtained from a soln. contg. respective compd. of Ba, Fe, Ni, Si and Zn, etc., in the specified rate, into hydrothermal treatment and calcining at the specified temp. CONSTITUTION:The starting raw material is the compd. of the respective element, which is in the relation of 1-12 gram atom of Fe to one gram atom of Ba, (x) gram atom of M1 (wherein, M1 is >=one sort of metal among Ni, Co, Cu, Mg and Mn), (y) gram atom of M2 (wherein, M2 is >=one sort of metal among Si, Ta, Sb, Nb, Zr and Ti) and (z) gram atom of Zn to (12-x-y-z) gram atom of Fe. The precipitate, which is obtained by adding the aq. soln. of the raw material with an alkaline hydroxide and making the alkali concentration to be >=3mol./l, is brought into hydrothermal treatment and calcined at the specified condition. Then, the magnetic powder of hexagonal plate-shaped magneto-plumbite type barium ferrite expressed in the chemical formula is obtained.
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