Wet process for preparing ferrites of magnetoplumbite structure in fine particle form
US4512906A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 6, 1984 |
| Grant date | Apr 23, 1985 |
| Priority date | — |
| Expiry date | Sep 6, 2004 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/60
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Fine particles of a ferrite having the magnetoplumbite structure are prepared by hydrothermal treatment of .gamma.-Fe.sub.2 O.sub.3 and at least one compound of a divalent metal selected from Ba, Sr and Pb in an aqueous alkali solution, preferably at 80.degree.-360.degree. C. This process is suitable for preparation of hexagonal and thin plate-shaped particles of the ferrite and is advantageous in consuming only a small quantity of alkali. Alternative to .gamma.-Fe.sub.2 O.sub.3, it is possible to use either Fe.sub.3 O.sub.4 or an intermediate iron oxide expressed by (FeO).sub.x.Fe.sub.2 O.sub.3, where O<x<1, as the starting iron oxide with the addition of an oxidizer to the hydrothermal reaction system to cause oxidation of the starting iron oxide to .gamma.-Fe.sub.2 O.sub.3 during an initial stage of the hydrothermal treatment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.