Solid solutions of magnetic oxides and method of preparation
US4096080A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1975 |
| Grant date | Jun 20, 1978 |
| Priority date | — |
| Expiry date | Oct 15, 1995 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B35/2683
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The invention concerns solid solutions of oxides of iron and of a divalent metal other than cobalt Co.sup.2+ or, alternatively, of iron and of more than one divalent metal, including cobalt. Besides Co, the divalent metals may be Ni, Cu, Mn, Zn, Mg and Cd. Such solutions are prepared by precipitating a mixed oxalate containing iron and the other divalent metal or metals desired. This mixed oxalate is decomposed by heating it in open air at a progressively increasing temperature until carbon is eliminated but without forming rhomboedric oxide .alpha.-Fe.sub.2 O.sub.3. The pyrolyzed product is treated by hydrogen and steam at an elevated temperature to obtain a substituted magnetite, and this magnetite is oxidized in air at such a temperature as to avoid formation of .alpha.-Fe.sub.2 O.sub.3.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.