Cation-treated silicate phosphor
AssigneeOsram Sylvania Inc.
InventorsAnthony L. Diaz, Charles F. Chenot, Shelley A. Sonner
Life of this patent
Estimating the term…
Abstract
A cation-treated silicate phosphor and fluorescent lamp made therefrom are provided wherein the 100 hour radiance maintenance is significantly improved. The cation treatment method involves adding an amount of a silicate phosphor to a salt solution containing a cation wherein the ratio of cation to phosphor in the solution is from about 1:2 to about 4:1 moles of cation to moles of phosphor. The solution is then stirred for a time sufficient to cause the cation to attach to the phosphor surface to form a cation-treated phosphor. The cation-treated phosphor is separated from the solution and annealed at a temperature and for a time sufficient to increase radiance maintenance of the cation-treated phosphor.
Claims20
A method for preparing a cation-treated silicate phosphor, comprising:
- adding an amount of a silicate phosphor to a salt solution containing a cation, the ratio of cation to phosphor in the solution being from about 1:2 to about 4:1 moles of cation to moles of phosphor;
- stirring the solution for a time sufficient to cause the cation to attach to the phosphor surface to form a cation-treated phosphor;
- separating the cation-treated phosphor from the solution;
- and
- annealing the cation-treated phosphor at a temperature and for a time sufficient to increase radiance maintenance of the cation-treated phosphor.
A method for preparing a cation-treated silicate phosphor, comprising:
- adding an amount of a silicate phosphor to a salt solution containing a cation, the ratio of cation to phosphor in the solution being from about 1:2 to about 4:1 moles of cation to moles of phosphor;
- stirring the solution for at least about 60 minutes to form a cation-treated phosphor;
- separating the cation-treated phosphor from the solution;
- and
- annealing the cation-treated phosphor at a temperature from about 700.degree. C. to about 1000.degree. C. for about 2 hours to about 7 hours.
A fluorescent lamp having a phosphor layer containing a cation-treated BaSi.sub.2 O.sub.5 :Pb phosphor and having a maintenance of at least about 82%.
A fluorescent lamp having a phosphor layer containing a BaSi.sub.2 O.sub.5 :Pb phosphor having a cation-treatment, the fluorescent lamp having a maintenance which is at least about 4% greater than a similar fluorescent lamp having a phosphor layer containing the same BaSi.sub.2 O.sub.5 :Pb phosphor without the cation treatment.
A cation-treated BaSi.sub.2 O.sub.5 :Pb phosphor comprising a BaSi.sub.2 O.sub.5 :Pb phosphor having a surface enriched in barium atoms whereby the ratio of silicon to barium surface atoms is 3.0 or less.
Dependencies are inferred from the claim text.