High efficiency alkaline earth metal thiogallate-based phosphors

• US 7,125,501 B2
• Filed: 04/13/2004
• Issued: 10/24/2006
• Est. Priority Date: 04/21/2003
• Status: Expired due to Term

• Current Assignee: Lightscape Materials, Inc. (DuPont de Nemours, Inc.)
• Original Assignee: Sarnoff Corporation (SRI International, Inc.)
• Inventors: Tian, Yongchi, Zaremba, Diane, Yocom, Perry Niel
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US10/823,267
• Publication Number:
  US 20040206936A1
• Time in Patent Office: 924 Days
• Field of Search: 252/301.4 S
• US Class Current: 252/301.40S
• CPC Class Codes: C01G 15/006 Compounds containing, besides gallium, indium, or thallium, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: C09K 11/7786 with alkaline earth metals

Abstract

Provided, among other things, is a strontium calcium thiogallate phosphor doped with divalent europium, and having the following formula:
Sr_1-xCa_xGa₂S₄:yEu²⁺.zGa₂S₃,
where x is 0.0001 to 1, y is a value defining sufficient Eu²⁺ to provide luminescent emission, and z is 0.0001 to 0.2 based on the mole amount of Sr_1-xCa_xGa₂S₄:yEu²⁺.

Claims

1. A strontium calcium thiogallate phosphor doped with divalent europium, and having the following formula:

Sr_1-xCa_xGa₂S₄;

yEu²⁺.zGa₂S₃,

where x is a value such that both Sr and Ca are present and is greater than or equal to 0.0001, y is a value defining sufficient Eu²⁺ to provide luminescent emission, and z is greater than 0.07 up to 0.2 based on the mole amount of Sr_1-xCa_xGa₂S₄.

2. The phosphor of claim 1, wherein z is 0.08 to 0.2.

3. The phosphor of claim 1, wherein z is 0.09 to 0.2.

4. The phosphor of claim 1, wherein y is 0.001 to 0.1 based on the mole amount of Sr_1-xCa_xGa₂S₄.

5. The phosphor of claim 4, wherein y is 0.01 to 0.08

6. The phosphor of claim 4, wherein y is 0.01 to 0.04.

7. The phosphor of claim 1, wherein the phosphor has an emission peak of 535 nm to 560 nm.

8. The phosphor of claim 7, wherein the emission peak has a bandwidth of 50 nm or less under excitation with an emission source at 440 nm±

40 nm.

9. The phosphor of claim 1, wherein the phosphor has an emission peak of 536 nm to 560 nm.

10. The phosphor of claim 1, wherein the phosphor has an emission peak of 537 nm to 560 nm.

11. The phosphor of claim 1, wherein the phosphor has an emission peak of 538 nm to 560 nm.

12. The phosphor of claim 1, wherein the phosphor has an emission peak of 539 nm to 560 nm.

13. The phosphor of claim 1, wherein the phosphor has an emission peak of 540 nm to 560 nm.

14. The phosphor of claim 1, wherein the phosphor has an emission peak of 541 nm to 560 nm.

15. The phosphor of claim 1, wherein the phosphor is made up of particles with primary particles that are in the size range 2–

4 microns.