Claims
- 1. A long persistence phosphor that emits in the orange-red portion of the spectrum comprisingAS:Eum:Trn:OxXy wherein A is an alkaline earth metal ion; Tr is one or more trivalent rare earth metal ions; X is a halogen; m is an integer in the range of 0.01-0.5 atomic percent; n is an integer in the range 0.03 to 0.5 atomic percent; x is an integer in the range 0.01 to 2.0 atomic percent; and y is an integer in the range of 0.01 to 0.5 atomic percent.
- 2. A phosphor according to claim 1 wherein the alkaline earth metal is selected from the group consisting of calcium, strontium and barium.
- 3. A phosphor according to claim 1 wherein the halogen is selected from the group consisting of fluorine, chlorine, bromine and iodine.
- 4. A phosphor according to claim 1 wherein Tr is one or more trivalent rare earth metal ions selected from the group consisting of praseodymium, gadolinium, dysprosium, holmium, terbium, neodymium and erbium.
- 5. A phosphor according to claim 1 wherein A is strontium and X is chlorine.
- 6. A phosphor according to claim 1 wherein A is strontium, m and n are 0.1, x is 1 and X is chlorine.
- 7. A method of making a long persistence phosphor that emits in the orange-red portion of the spectrum comprisinga) mixing an alkaline earth metal sulfate doped with europium and one or more trivalent rare earth metals with a hydrocarbon and sulfur in a closed refractory crucible; b) heating the mixture slowly up to a first temperature of about 400° C. and c) heating to a final temperature of about 900-1200° C. in said crucible until the corresponding oxygen containing sulfide phosphor is formed.
- 8. A method according to claim 7 wherein the alkaline earth metal is selected from the group consisting of strontium, calcium and barium.
- 9. A method according to claim 7 wherein the trivalent rare earth metal is selected from the group consisting of one or more of praseodymium, neodymium, gadolinium, dysprosium, holmium, terbium and erbium.
- 10. A method according to claim 7 wherein the oxide-containing sulfide phosphor is heated with a halogen compound to form the corresponding halide and oxide-containing phosphor.
- 11. A method according to claim 7 wherein after step c), the phosphor is ground, mixed with a hydrocarbon and sulfur in a closable crucible and steps b) and c) are repeated.
Parent Case Info
This application claims the benefit of U.S. Provisional Application Serial No. 60/125,875 filed Mar. 24, 1999.
US Referenced Citations (7)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0030853 |
Jun 1981 |
EP |
56-82876 |
Jul 1981 |
JP |
Non-Patent Literature Citations (1)
Entry |
International Search Report for PCT/US00/07929, filed Mar. 24, 2000. |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/125875 |
Mar 1999 |
US |