Method for preparing zinc orthosilicate phosphor particle
US5196234A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 20, 1992 |
| Grant date | Mar 23, 1993 |
| Priority date | — |
| Expiry date | Jul 20, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J61/48
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A method for preparing a specific zinc orthosilicate phosphor particle having a nonparticulate, conformal aluminum oxide coating wherein all of a manganese activator is present as manganese (II) and occupies zinc (II) sites includes the steps of blending a zinc source, a manganese (II) source, a silicon source, and a tungsten source in amounts in accordance with said formula with an amount of up to about 2 weight percent NH.sub.4 Cl and up to about 0.2 weight percent NH.sub.4 F to form a relatively uniform admixture, firing the mixture in a closed container under an inert non-oxidizing atmosphere to promote retention of manganese in the plus two valance state whereby oxidation of manganese to a higher valence state is avoided and conditions promote larger particle size formation; milling and washing the phosphor in an aqueous citric acid solution to remove unreacted manganese; rinsing, drying and sieving the dried phosphor; and depositing a continuous, nonparticulate, conformal aluminum oxide coating on the dried phosphor particle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.