Wet process of preparing fine particles of ferrite of magnetoplu

Details Wet process of preparing fine particles of ferrite of magnetoplu Wet process of preparing fine particles of ferrite of magnetoplu

1984-07-24

1985-11-05

Cooper, Jack

Compositions

Magnetic

Iron-oxygen compound containing

252 626, 252 6262, 252 6263, 252 6264, C04B 3526

Patent

active

045512604

ABSTRACT:
In preparing fine and plate-shaped particles of a ferrite having the magnetoplumbite structure by hydrothermal treatment of a powder of .gamma.-Fe.sub.2 O.sub.3 or (FeO).sub.x.Fe.sub.2 O.sub.3, where O<x.ltoreq.1, and a compound of Ba, Sr or Pb in an aqueous alkali solution, Sn.sup.4+, or Sn.sup.4+ and M.sup.2+ such as Fe.sup.2+, Cu.sup.2+ or Zn.sup.2+, are introduced into the reaction system of the hydrothermal treatment such that Fe.sup.3+ in the obtained ferrite are partly substituted by Sn.sup.4+ or M.sup.2+ -Sn.sup.4'. The substitution has the effect of lowering the coercive force of the ferrite powder to a level suitable for use in magnetic recording media of the perpendicularly magnetizing recording type. By using an iron oxide powder having a mean particle size not larger than 500 .ANG. with addition of a surface-active agent, the particle size of the ferrite powder can be reduced to about 0.2 .mu.m.

REFERENCES:
patent: 4341648 (1982-07-01), Kubo et al.
patent: 4407721 (1983-10-01), Koike et al.
"Structural and Magnetic Studies of Hydrothermally Synthesized New Ferrites", Research Bulletin of Nagaoka Institute of Science and Technology, No. 4 (1982).

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