Method for preparing YAG fluorescent powder

• US 20060145124A1
• Filed: 12/29/2005
• Published: 07/06/2006
• Est. Priority Date: 12/31/2004
• Status: Abandoned Application

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Huang, Chun-Ju, Shih, Ming-Shiann, Tsai, Ming-Shyong, Huang, Jau-Chyn, Huang, Ting-Wei, Hsiao, Ching-Sung
• Application Number:
  US11/319,542
• Publication Number:
  US 20060145124A1
• Time in Patent Office: Days
• US Class Current: 252/301.40R
• CPC Class Codes: C09K 11/77 containing rare earth metals

Abstract

The present invention relates to a process of making YAG fluorescence powder which comprises steps of: (a) providing a first solution of anions and a second solution of cations; (b) mixing the first solution of anions and the second solution of cations drop by drop and forming a precipitate; (c) collecting the precipitate and drying it; (d) annealing the precipitate under a pre-determined temperature until powder occurs; (e) sintering the annealed powder with a plasma torch for at least once; and (f) collecting the sintered powder.

Claims

1. A method for preparing fluorescent powder of Yttrium Aluminum Garnet, comprising following steps:

(a) providing a first solution of anions and a second solution of cations;

(b) mixing said first solution of anions and said second solution of cations through dripping to form a precipitate;

(c) collecting and drying said precipitate;

(d) annealing said dried precipitate to form powder;

(e) sintering said powder with a plasma torch; and

(f) collecting said sintered powder.

2. The method of claim 1, wherein said first solution of anions comprising oxalic acid, citric acid, ammonium carbonate, ammonia or the mixture thereof.

3. The method of claim 1, wherein said second solution of cations comprising a nitrate or nitrate oxide of (Y₃-_aR_a)Al₅O₁₂, in which R is an element of rare earth, Cerium (Ce), Dysprosium (Dy), Gadolinium (Gd), Europium (Eu), Terbium (Tb), Lanthanum (La), Praseodymium (Pr), Neodymium (Nd), Samarium (Sm) or Cobalt (Co), and the a in the formula of nitrate or nitrate oxide is 0.01 to 0.2.

4. The method of claim 1, wherein said dripping in step (b) is to have said first solution of anions dripped into said second solution of cations.

5. The method of claim 1, wherein said dripping in step (b) is at a rate of 0.5 to 5 milliliter per minute.

6. The method of claim 5, wherein said rate of dripping is 1 milliter per minute.

7. The method of claim 1, wherein the conditions of said drying in step (c) are at 80 to 100°

C. and for 12 to 36 hours.

8. The method of claim 7, wherein the conditions of said drying in step (c) are at 95°

C. and for 12 hours.

9. The method of claim 1, wherein said temperature in step (d) is in the range from 800 to 1500°

C.

10. The method of claim 9, wherein said temperature in step (d) is 900°

C.

11. The method of claim 1, wherein said temperature in step (d) is increased at a rate of 5 to 15°

C. per minute.

12. The method of claim 11, wherein said temperature in step (d) is increased at 10°

C. per minute.

13. The method of claim 1, wherein said annealing in step (d) lasts 0.5 to 12 hours.

14. The method of claim 13, wherein said annealing in step (d) lasts 1 hour.

15. The method of claim 1, wherein said plasma torch is a negative-pressure type microwave plasma torch.

16. The method of claim 7, wherein the gases used for said plasma torch in step (d) are helium, hydrogen, nitrogen, air or the combination thereof.

17. The method of claim 7, wherein the pressure used for said microwave plasma torch in step (d) is 20 to 740 Torr.

18. The method of claim 1, wherein said sintering temperature in step (e) is 2000 to 4000°

C.