Processes for preparing stable red-emitting phosphors

Patent metadata

Field	Value
Publication number	US-10731076-B2
Application number	US-201715794759-A
Country	US
Kind code	B2
Filing date	Oct 26, 2017
Priority date	Dec 1, 2016
Publication date	Aug 4, 2020
Grant date	Aug 4, 2020

Abstract

Processes for producing stable Mn 4+ doped phosphors include dispersing a compound of formula I in a solution comprising a compound of formula II to form a dispersion;

applying pressure to the dispersion at a temperature less than 200° C. to form a phosphor product; and contacting the phosphor product with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature;
wherein A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MF y ] ion; and y is 5, 6 or 7.

First claim

The invention claimed is:

1. A process comprising
dispersing a compound of formula I in a solution comprising a compound of formula II to form a dispersion;

applying pressure to the dispersion at a temperature less than 200° C. to form a phosphor product; and
contacting the phosphor product with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature;
wherein
A is Li, Na, K, Rb, Cs, or a combination thereof;
M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof;
x is the absolute value of the charge of the [MF y ] ion; and
y is 5, 6 or 7.

2. A process according to claim 1 , wherein the pressure is less than 100 bar.

3. A process according to claim 1 , wherein the pressure ranges from about 60 bar to about 100 bar.

4. A process according to claim 1 , wherein the pressure is applied for a time less than 4 hours.

5. A process according to claim 1 , wherein the pressure is applied for a time less than 1 hour.

6. A process according to claim 1 , wherein the temperature ranges from about 100° C. to less than 200° C.

7. A process according to claim 1 , wherein the temperature ranges from about 130° C. to 160° C.

8. A process according to claim 1 , additionally comprising exposing the dispersion to microwave radiation while applying pressure.

9. A process according to claim 1 , additionally comprising contacting the color stable Mn4+ doped phosphor in particulate form with a solution of a composition of formula II in aqueous hydrofluoric acid.

10. A process according to claim 1 , wherein the fluorine-containing oxidizing agent is F 2 .

11. A process according to claim 1 , wherein M is Si, Ge, Sn, Ti, Zr, or a combination thereof.

12. A process according to claim 1 , wherein
A is Na, K, Rb, Cs, or a combination thereof;
M is Si, Ge, Ti, or a combination thereof; and
Y is 6.

13. A process according to claim 1 , wherein the compound of formula I is K 2 SiF 6 :Mn 4+ .

14. A process for synthesizing a color stable Mn 4+ doped phosphor, the process comprising applying pressure to a dispersion at a temperature less than 200° C. to form a first phosphor product, the dispersion comprising a compound of formula I, a compound of formula II and hydrofluoric acid;

wherein
A is Li, Na, K, Rb, Cs, or a combination thereof;
M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof;
x is the absolute value of the charge of the [MF y ] ion; and
y is 5, 6 or 7.

15. A process comprising
contacting a compound of formula I with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature to form phosphor product;
A x [MF y ]:Mn 4+    I

dispersing the phosphor product in a solution comprising a compound of formula II and hydrofluoric acid; and
A x [MF y ]   II

applying pressure to the dispersion at a temperature less than 200° C.;
wherein
A is Li, Na, K, Rb, Cs, or a combination thereof;
M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof;
x is the absolute value of the charge of the [MF y ] ion; and
y is 5, 6 or 7.

16. A process according to claim 15 , wherein the pressure is less than 100 bar.

17. A process according to claim 15 , wherein the pressure ranges from about 60 bar to about 100 bar.

18. A process according to claim 15 , wherein the pressure is applied for a time less than 4 hours.

19. A process according to claim 15 , wherein the pressure is applied for a time less than 1 hour.

20. A process according to claim 15 , wherein the temperature ranges from about 100° C. to less than 200° C.

21. A process according to claim 15 , wherein the temperature ranges from about 130° C. to 160° C.

22. A process according to claim 15 , additionally comprising exposing the dispersion to microwave radiation while applying pressure.

23. A process according to claim 15 , additionally comprising contacting the color stable Mn4+ doped phosphor in particulate form with a solution of a composition of formula II in aqueous hydrofluoric acid.

24. A process according to claim 15 , wherein the fluorine-containing oxidizing agent is F 2 .

25. A process according to claim 15 , wherein M is Si, Ge, Sn, Ti, Zr, or a combination thereof.

26. A process according to claim 15 , wherein
A is Na, K, Rb, Cs, or a combination thereof;
M is Si, Ge, Ti, or a combination thereof; and
Y is 6.

27. A process according to claim 15 , wherein the compound of formula I is K 2 SiF 6 :Mn 4+ .

Assignees

• Current Lighting Solutions Llc

Inventors

• Setlur Anant Achyut
• Murphy James Edward

Classifications

• C09K11/617 Primary

  Silicates · CPC title