Method for preparing dicalcium orthophosphate for use in fluorescent lamp phosphors
US4178355A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 17, 1978 |
| Grant date | Dec 11, 1979 |
| Priority date | — |
| Expiry date | Feb 17, 1998 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B25/327
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method of preparing anhydrous dicalcium orthophosphate of predetermined and substantially uniform particle size for use in making fluorescent lamp phosphors. The method entails heating an acidified aqueous slurry of hydrated dicalcium orthophosphate in a reaction vessel and at the same time agitating the heated slurry. The heating and simultaneous agitation is continued until significant incipient formation of a gel-like material is manifested at the wall portions of the reaction vessel. At that point the application of heat to the slurry is discontinued. The agitation of the slurry within the vessel is continued until all the slurry is converted to meta-stable gel-like material. At that time the agitation is discontinued. The formed meta-stable gel-like material is then maintained in a quiescent state until it converts completely to crystals of dicalcium orthophosphate. The orthophosphate crystals are then permitted to settle to the bottom of the residual liquid in the vessel. The settled crystals are then separated from the residual liquid.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.