ZnS:Cu electroluminescent phosphor and method of making same

A method for increasing the halflife of a ZnS:Cu electroluminescent phosphor comprising:

• blending amounts of zinc sulfide, a copper source, a gold source and a chloride flux to form a mixture;
• firing the mixture at a temperature from about 900.degree. C. to about 1400.degree. C. for about 2 hours to about 8 hours to form a zinc sulfide material containing copper, chlorine and gold;
• subjecting the zinc sulfide material to a low intensity milling for between about 190 minutes to about 280 minutes to form a milled material;
• blending the milled material with an amount of zinc sulfate and an amount of copper sulfate;
• and
• refiring the blended milled material at a temperature from about 500.degree. C. to about 1000.degree. C. for about 1 to 5 hours to form an electroluminescent phosphor.

An electroluminescent lamp comprising:

• a first electrode, a first layer of dielectric material adjacent to the first electrode, a second layer of a dielectric material adjacent to the first layer;
• the second layer containing an electroluminescent phosphor having a general formula ZnS:Cu,Cl,Au, a halflife of at least about 900 hours, and x and y color coordinates where the x color coordinate is from about 0.156 to about 0.196 and the y color coordinate is from about 0.370 to about 0.430;
• and
• a second electrode adjacent to the second layer of dielectric material.