Recovery of gadolinium and gallium oxides
US4375453A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 28, 1981 |
| Grant date | Mar 1, 1983 |
| Priority date | — |
| Expiry date | Dec 28, 2001 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/80
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Gd.sub.2 O.sub.3 and Ga.sub.2 O.sub.3 are currently used for the fabrication of Gd.sub.3 Ga.sub.5 O.sub.12 (GGG) wafers which are employed as substrates for bubble domain memory devices. In the processing, in the order of 25% of the starting material ends up as process "saw kerf" contaminated with variable amounts of iron, nickel, magnesium, aluminum, zirconium, iridium and silicon. A process is described whereby the "saw kerf" can be reprocessed in sufficient purity to be re-used in the process, thereby improving the economics of production of GGG wafers significantly. Gadolinium and gallium oxides are recovered and separated from transition metal impurities introduced during fabrication of GGG wafers. The process "saw kerf" produced from slicing the crystal boule is dissolved in HCl, treated with H.sub.2 SO.sub.4, and the resulting sulfates separated. Metathesis with (NH.sub.4).sub.2 C.sub.2 O.sub.4 results in conversion of the sulfates to the ammonium oxalates which were calcined at 850.degree. C. to form Ga.sub.2 O.sub.3 and Gd.sub.2 O.sub.3 of purity >99.99%. The process can be extended to include purification and re-use of by-products generated in other grinding and polishing…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.