Processes for preparing color stable manganese-doped phosphors

Patent metadata

Field	Value
Publication number	US-9399732-B2
Application number	US-201414465024-A
Country	US
Kind code	B2
Filing date	Aug 21, 2014
Priority date	Aug 22, 2013
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

Abstract

Low-HF or HF-free processes for improving color stability of a Mn +4 doped phosphor of formula I include contacting the phosphor of formula I with a solution that contains hexafluorosilicic acid, and isolating a treated phosphor of formula I having improved color stability relative to an untreated phosphor of formula I

A x [MF y ]:Mn +4   (I)
wherein A is Li, Na, K, Rb, Cs, R 4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, 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 for improving color stability of a Mn +4 doped phosphor of formula I,
A x [MF y ]:Mn +4   (I)

the process comprising treating the phosphor of formula I with a manganese free solution comprising hexafluorosilicic acid; and
isolating a treated phosphor having improved color stability relative to an untreated phosphor;
wherein
A is Li, Na, K, Rb, Cs, R 4 or a combination thereof;
M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof;
R is H, lower alkyl, or a combination thereof;
x is 1, 2, or 3, and 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 solution additionally comprises a salt of formula A x [MF y ].

3. A process according to claim 1 , wherein the solution is free of hydrofluoric acid.

4. A process according to claim 1 , wherein the solution additionally comprises hydrofluoric acid.

5. A process according to claim 1 , additionally comprising exposing the phosphor to fluorine gas at elevated temperature.

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

7. A process according to claim 1 , wherein the Mn +4 doped phosphor is K 2 SiF 6 :Mn +4 .

8. A process for improving color stability of a complex fluoride compound of formula K 2 SiF 6 :Mn +4 , the process comprising treating the phosphor with a manganese free solution comprising hexafluorosilicic acid; and isolating a treated phosphor formula K 2 SiF 6 :Mn +4 having improved color stability relative to an untreated phosphor formula K 2 SiF 6 :Mn +4 .

9. A process according to claim 8 , wherein the solution additionally comprises K 2 SiF 6 .

10. A process according to claim 8 , wherein the solution is free of hydrofluoric acid.

11. A process according to claim 8 , wherein the solution additionally comprises hydrofluoric acid.

12. A process according to claim 8 , additionally comprising exposing the phosphor to fluorine gas at elevated temperature.

Assignees

• Gen Electric

Inventors

• Murphy James Edward

Classifications

• F21V13/08

  the elements being filters or photoluminescent elements and reflectors · CPC title

• F21V9/38

  Combination of two or more photoluminescent elements of different materials · CPC title

• F21V3/12

  the coatings comprising photoluminescent substances · CPC title

• H10W90/756

  between a chip and a stacked lead frame, conducting package substrate or heat sink · CPC title

• H10W74/00

  Encapsulations, e.g. protective coatings · CPC title