Electroluminescent phosphor powder with D50 value of less than 12 μm and method of making
US7291291B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 2005 |
| Grant date | Nov 6, 2007 |
| Priority date | — |
| Expiry date | Dec 30, 2025 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09K11/584
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
There is presented an electroluminescent phosphor powder of copper-activated zinc sulfide particles that has a size distribution with a D50 value of less than 12 μm, and more preferably less than 10 μm. The powder is preferably made by a method that includes the steps of combining copper-doped zinc sulfide with sulfur, zinc oxide and a chloride-containing flux to form a first mixture; preliminarily firing the first mixture and milling the preliminarily fired first mixture to form a milled material having a D50 value of less than or equal to about 5 μm; blending the milled material with sulfur, zinc oxide and a chloride-containing flux to form a second mixture; firing the mixture in a first firing step at a temperature in a range of about 1020° C. to about 1080° C. to form a hexagonal zinc sulfide material; inducing defects into the hexagonal zinc sulfide material; firing the hexagonal zinc sulfide material in a second firing step at a temperature in a range of about 650° C. to about 850° C. to form an electroluminescent phosphor; and sifting the electroluminescent phosphor to provide an electroluminescent phosphor powder comprising phosphor particles that have a size distribution w…
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