Cryochemical method of preparing ultrafine particles of high-purity superconducting oxides
US4975415A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 1987 |
| Grant date | Dec 4, 1990 |
| Priority date | — |
| Expiry date | Jul 10, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S505/742
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention pertains to a method of preparing particles of superconducting ceramic powders, which method comprises: PA0 (a) dissolving the soluble salts of the cations in aqueous medium; PA0 (b) obtaining a solution having pH of between about 4 and 7 by optionally treating the aqueous medium with ammonia, or ammonium hydroxide; PA0 (c) atomizing the solution of step (b) onto liquid nitrogen at about -196.degree. C.; PA0 (d) removing the liquid nitrogen by evaporation; PA0 (e) removing the water by sublimation at reduced pressure; PA0 (f) heating the solid residue of step (e) at 40-60.degree. C. at reduced pressure; PA0 (g) calcining the solid residue in flowing oxygen or air at temperature of between about 200.degree. to 895.degree. C.; and PA0 (h) cooling the solid at a temperature of between about 900.degree. C. and ambient temperature in sufficient air or oxygen and recovering the superconducting powder having an average diameter of between about 0.1 and 10 microns. Optionally, substep (h), additionally includes during cooling, the annealing of the particles in sufficient oxygen at between about 200.degree. and 500.degree. C. for between about 2 and 30 hrs. YBa.sub.2 C…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.