Method of improving the maintenance of a fluorescent lamp containing europium-activated barium magnesium silicate phosphor

Claim 1

A process for improving the initial power output and maintenance of a fluorescent lamp containing europium-activated barium magnesium silicate phosphor having the general formulation BaMg 2 Si 2 O 7 :Eu and an atomic concentration of component elements at its particle surfaces of 2.3% barium, 1.4% europium, 25% magnesium, 15% silicon and the balance oxygen, comprising the steps of: a) combining said europium-activated barium magnesium silicate phosphor with a flux selected from the group consisting of barium fluoride, barium silicofluoride, magnesium silicofluoride, ammonium silicofluoride, ammonium fluoride, magnesium fluoride, calcium fluoride, and strontium fluoride, said flux being in an amount of between about 0.06% and 0.25% by weight of the phosphor/flux mixture to form a uniform mixture; b) firing said mixture in a reducing atmosphere at a temperature of about 1150° C. to about 1300° C. for about 2 to 6 hours; c) washing said fired mixture in an aqueous solution of potassium hydroxide; d) removing said potassium hydroxide solution from said fired mixture and washing the resulting potassium hydroxide-washed mixture with deionized water; e) filtering, drying and screening the resulting washed mixture to obtain a treated europium-activated barium magnesium silicate phosphor; and f) coating the interior of a fluorescent lamp envelope with said treated phosphor.