Method of making electroluminescent phosphors with small particle sizes and powder with D50 value of no more than 10 micrometers
US7288216B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 2005 |
| Grant date | Oct 30, 2007 |
| Priority date | — |
| Expiry date | Dec 30, 2025 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09K11/584
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electroluminescent phosphor powder includes copper-activated zinc sulfide particles that have a size distribution with a D50 value of no more than 10 μm, where no more than 25% of the particles have a size greater than about 15 μm and/or a 24-hr brightness of at least 15 footlamberts. These particles are made by a method that includes first firing copper-doped zinc sulfide mixed with zinc oxide, sulfur and a chloride-containing flux, rapidly cooling the mixture to below 100° C., and then mulling and second firing the mixture to provide a powder. The powder can then be elutriated to provide the electroluminescent powder with a narrow particle size distribution (more than 90% between about 5 and 15 μm). The elutriating step can be avoided (albeit with a slightly wider size distribution) by more tightly controlling the first firing temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.