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Process for producing electroluminescent phosphors of improved brightness

  • US 4,859,361 A
  • Filed: 01/17/1989
  • Issued: 08/22/1989
  • Est. Priority Date: 05/13/1988
  • Status: Expired due to Term
First Claim
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1. A process for producing an electroluminescent phosphor comprising:

  • (a) blending a chloride flux, a copper source, and zinc sulfide to form a relatively uniform admixture;

    (b) heating the resulting admixture at a temperature of from about 1000°

    C. to about 1300°

    C. for about 2 to about 8 hours to convert at least a portion of the admixture to a crystalline material containing zinc sulfide, at least some chloride ions, and copper ions,(c) washing the resulting material with sufficient water to remove at least a major portion of the water soluble material from the crystalline material;

    (d) drying the washed material to produce a relatively moisture-free material;

    (e) subjecting said relatively moisture-free material to low intensity milling for a sufficient time to change the crystallographic structure of at least a portion of the moisture-free material from a hexagonal structure to a cubic structure;

    (f) blending the resulting milled material with zinc sulfate and copper sulfate to form a second admixture;

    (g) heating said second admixture at a temperature of from about 750°

    C. to about 850°

    C. for about 1.5 to about 3 hours to form an activated material;

    (h) cooling said activated material by allowing it to stand at room temperature for a period of time of from about 10 minutes to about 20 minutes followed by immediately quenching said cooled material in water;

    (i) removing said water from the resulting cooled and quenched activated material;

    (j) washing said quenched activated material to remove residual fluxes and excess activator materials;

    (k) drying the resulting washed material to form an electroluminescent phosphor.

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