Firing and milling method for producing a manganese activated zi

Details Firing and milling method for producing a manganese activated zi Firing and milling method for producing a manganese activated zi

1988-12-22

1990-05-15

Cooper, Jack

Coating processes

Particles, flakes, or granules coated or encapsulated

Inorganic base

2523015, 2523016F, 4273722, C09K 1159

Patent

active

049257030

ABSTRACT:
A manganese activated zinc silicate phosphor and method for producing same is disclosed which comprises dry blending a mixture of components consisting essentially of zinc oxide, silicic acid, a source of manganese, ammonium chloride, ammonium fluoride, tungstic oxide and silica wherein the Zn+Mn/Si mole ratio is from about 1.95 to about 2.02, wherein the silica is colloidal and has a surface area of from about 50 to about 410 m.sup.2 /g, and wherein the colloidal silica makes up from about 0.01% to about 1.0% by weight, firing the blend in a nitrogen atmosphere at a temperature of from about 1200.degree. C. to about 1300.degree. C. for a sufficient time to produce the phosphor, and firing the phosphor in air at a temperature of from about 1175.degree. C. to about 1275.degree. C. for a sufficient time to diffuse the tungsten and manganese to the surfaces of the phosphor particles. Between the firing steps, the phosphor can be milled for from about 60 to 120 minutes to increase luminescence. The phosphor can be coated with a continuous coating of aluminum oxide and annealed to improve maintenance of the phosphor. A fluorescent lamp incorporating the phosphor is also disclosed.

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patent: 4585673 (1986-04-01), Sigai
patent: 4710674 (1987-12-01), Sigai
patent: 4728459 (1988-03-01), Fan et al.
patent: 4803400 (1989-02-01), Peters et al.
patent: 4825124 (1989-04-01), Sigai

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