Method for improving a manganese activated zinc silicate phosphor

Claim 1

A method of improving the reflectivity of a manganese activated zinc silicate phosphor powder having cations consisting essentially of zinc, silicon, manganese, and tungsten and having a 350 nm reflectance less than 80%, and a 275 nm reflectance greater than 13.5% comprising the following steps: Step 1--heating said phosphor powder in a furnace to a temperature of about 1225° C. in air; Step 2--cooling said phosphor powder from Step 1; Step 3--wet milling said phosphor powder from Step 2 in an acid solution; Step 4--separating said phosphor powder from Step 3 from said acid solution; Step 5--washing said phosphor powder from Step 4 with water; and Step 6--drying said phosphor powder from Step 5 to form a manganese activated zinc silicate phosphor powder having a 350 nm reflectance equal to or greater than 80%, and a 275 nm reflectance equal to or less than 13.5%.

Claim 2

A method of improving the reflectivity of a manganese activated zinc silicate phosphor powder having cations consisting essentially of zinc, silicon, manganese, and tungsten and having a 350 nm reflectance less than 80%, and a 275 nm reflectance greater than 13.5% comprising the following steps: Step 1--heating said phosphor powder in a furnace to a temperature of about 1225° C. in air; Step 2--cooling said phosphor powder from Step 1; Step 3--wet milling said phosphor powder from Step 2 in an acid solution; Step 4--separating said phosphor powder from Step 3 from said acid solution; Step 5--washing said phosphor powder from Step 4 with water; and Step 6--drying said phosphor powder from Step 5 to form a manganese activated zinc silicate phosphor powder having a 350 nm reflectance equal to or greater than 80%, and a 275 nm reflectance equal to or less than 13.5%.

Claim 7

A method of improving the reflectivity of a manganese activated zinc silicate phosphor powder having cations consisting essentially of zinc, silicon, manganese, and tungsten and having a 350 nm reflectance less than 80%, and a 275 nm reflectance greater than 13.5% comprising the following steps: Step 1--heating said phosphor powder in a furnace to a temperature of about 1225° C. in air; Step 2--maintaining said temperature of Step 1 for a period of about four to about 16 hours; Step 3--cooling said phosphor powder from Step 2 to a temperature of about 900° C.; Step 4--removing said phosphor powder from Step 3 from said furnace and cooling said phosphor powder to room temperature; Step 5--roll crushing said phosphor powder from Step 4; Step 6--sieving said phosphor powder from Step 5 through a 60 mesh screen; Step 7--wet milling said phosphor powder from Step 6 in a citric acid solution; Step 8--separating said phosphor powder from Step 7 from said citric acid solution; Step 9--dispersing said phosphor powder from Step 8 in distilled water; Step 10--settling said phosphor powder from Step 9 for about 15 minutes; Step 11--separating said phosphor powder from Step 10 from the distilled water by decantation; Step 12--repeating Steps 9 through 11; Step 13--drying said phosphor powder from Step 12; and Step 14--sieving said phosphor powder from Step 13 through a 400 mesh screen to form a sieved phosphor powder having a 350 nm reflectance equal to or greater than 80% and a 275 nm reflectance equal to or less than 13.5%.

Claim 8

A method of improving the reflectivity of a manganese activated zinc silicate phosphor powder having cations consisting essentially of zinc, silicon, manganese, and tungsten and having a 350 nm reflectance less than 80%, and a 275 nm reflectance greater than 13.5% comprising the following steps: Step 1--heating said phosphor powder in a furnace to a temperature of about 1225° C. in air; Step 2--maintaining said temperature of Step 1 for a period of about four to about 16 hours; Step 3--cooling said phosphor powder from Step 2 to a temperature of about 900° C.; Step 4--removing said phosphor powder from Step 3 from said furnace and cooling said phosphor powder to room temperature; Step 5--roll crushing said phosphor powder from Step 4; Step 6--sieving said phosphor powder from Step 5 through a 60 mesh screen; Step 7--wet milling said phosphor powder from Step 6 in a citric acid solution; Step 8--separating said phosphor powder from Step 7 from said citric acid solution; Step 9--dispersing said phosphor powder from Step 8 in distilled water; Step 10--settling said phosphor powder from Step 9 for about 15 minutes; Step 11--separating said phosphor powder from Step 10 from the distilled water by decantation; Step 12--repeating Steps 9 through 11; Step 13--drying said phosphor powder from Step 12; and Step 14--sieving said phosphor powder from Step 13 through a 400 mesh screen to form a sieved phosphor powder having a 350 nm reflectance equal to or greater than 80% and a 275 nm reflectance equal to or less than 13.5%.

Claim 9

A Method of improving the reflectivity of a manganese activated zinc silicate phosphor powder having cations consisting essentially of zinc, silicon, manganese, and tungsten and having a 350 nm reflectance less than 80%, and a 275 nm reflectance greater than 13.5% comprising the following steps: Step 1--heating said phosphor powder in a furnace to a temperature of about 1225° C. in air; Step 2--cooling said phosphor powder from Step 1; Step 3--wet milling said phosphor powder from Step 2 in an acid solution; Step 4--separating said phosphor powder from Step 3 from said acid solution; Step 5--washing said phosphor powder from Step 4 with water; Step 6--drying said phosphor powder from Step 5; Step 7--adding NH 4 Cl to said phosphor powder from Step 6 to form a mixture of said NH 4 Cl and said phosphor powder; Step 8--heating said mixture of said NH 4 Cl and said phosphor powder from Step 7 in a furnace to a temperature of about 1000° C. in air; Step 9--cooling said phosphor powder from Step 8; Step 10--wet milling said phosphor powder from Step 9 in an acid solution; Step 11--separating said phosphor powder from Step 10 from said acid solution; Step 12--washing said phosphor powder from Step 11 with water; and Step 13--drying said phosphor powder from Step 12 to form a manganese activated zinc silicate phosphor powder having a 350 nm reflectance equal to or greater than 80%, and a 275 nm reflectance equal to or less than 13.5%.

Claim 10

A Method of improving the reflectivity of a manganese activated zinc silicate phosphor powder having cations consisting essentially of zinc, silicon, manganese, and tungsten and having a 350 nm reflectance less than 80%, and a 275 nm reflectance greater than 13.5% comprising the following steps: Step 1--heating said phosphor powder in a furnace to a temperature of about 1225° C. in air; Step 2--cooling said phosphor powder from Step 1; Step 3--wet milling said phosphor powder from Step 2 in an acid solution; Step 4--separating said phosphor powder from Step 3 from said acid solution; Step 5--washing said phosphor powder from Step 4 with water; Step 6--drying said phosphor powder from Step 5; Step 7--adding NH 4 Cl to said phosphor powder from Step 6 to form a mixture of said NH 4 Cl and said phosphor powder; Step 8--heating said mixture of said NH 4 Cl and said phosphor powder from Step 7 in a furnace to a temperature of about 1000° C. in air; Step 9--cooling said phosphor powder from Step 8; Step 10--wet milling said phosphor powder from Step 9 in an acid solution; Step 11--separating said phosphor powder from Step 10 from said acid solution; Step 12--washing said phosphor powder from Step 11 with water; and Step 13--drying said phosphor powder from Step 12 to form a manganese activated zinc silicate phosphor powder having a 350 nm reflectance equal to or greater than 80%, and a 275 nm reflectance equal to or less than 13.5%.