| 发明名称 |
Wet process of preparing fine particles of ferrite of magnetoplumbite structure |
| 摘要 |
In preparing fine and plate-shaped particles of a ferrite having the magnetoplumbite structure by hydrothermal treatment of a powder of gamma -Fe2O3 or (FeO)x.Fe2O3, where O<x</=1, and a compound of Ba, Sr or Pb in an aqueous alkali solution, Sn4+, or Sn4+ and M2+ such as Fe2+, Cu2+ or Zn2+, are introduced into the reaction system of the hydrothermal treatment such that Fe3+ in the obtained ferrite are partly substituted by Sn4+ or M2+-Sn4'. 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 ANGSTROM with addition of a surface-active agent, the particle size of the ferrite powder can be reduced to about 0.2 mu m.
|
| 申请公布号 |
US4551260(A) |
申请公布日期 |
1985.11.05 |
| 申请号 |
US19840634023 |
申请日期 |
1984.07.24 |
| 申请人 |
CENTRAL GLASS COMPANY LIMITED |
发明人 |
HAYAKAWA, MASANORI;YAMADA, NORIAKI;KAWAMOTO, HIROMI;NISHIMURA, SATOSHI |
| 分类号 |
C01G49/00;C01G51/00;C01G53/00;G11B5/706;H01F1/11;(IPC1-7):C04B35/26 |
主分类号 |
C01G49/00 |
| 代理机构 |
|
代理人 |
|
| 主权项 |
|
| 地址 |
|
