Granted Patent B2

US 10,047,286 · App. 14/950,644 · Granted Aug 14, 2018

Abstract

Claims (29)

1. A process for preparing a Mn +4 doped phosphor of formula I

A x [MF y ]:Mn +4   I

the process comprising gradually adding a first solution comprising a source of M and HF and a second solution comprising a source of Mn to a reactor in the presence of a source of A to form a product liquor comprising the Mn +4 doped phosphor; and

periodically discharging at least a portion of the product liquor from the reactor; wherein

A is Li, Na, K, Rb, Cs, 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;

x is the absolute value of the charge of the [MF y ] ion;

y is 5, 6 or 7;

isolating the Mn +4 doped phosphor from the product liquor; and contacting the Mn +4 doped phosphor at an elevated temperature with a fluorine-containing oxidizing agent in gaseous form to form a color stable Mn +4 doped phosphor of formula I.

2. A process according to claim 1 , additionally comprising an initial period wherein the first and second solutions are gradually added to the reactor without discharging the product liquor.

3. A process according to claim 1 , additionally comprising precharging the reactor with a material selected from HF, a source of A, preformed particles of the Mn +4 doped phosphor, or a combination thereof.

4. 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.

5. A process according to claim 1 , wherein M is Si.

6. A process according to claim 1 , wherein the Mn +4 doped phosphor of formula I is K 2 SiFe 6 :Mn 4+ .

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

8. A process for preparing a color stable Mn +4 doped phosphor of formula I,

A x [MF y ]:Mn +4   I

the process comprising gradually adding a first feed comprising HF and a source of M and a second feed comprising a source of Mn to a reactor in the presence of a source of A, to form a product liquor comprising the Mn +4 doped phosphor;

periodically discharging the product liquor from the reactor while volume of the product liquor in the reactor remains constant;

isolating the Mn +4 doped phosphor from the product liquor; and

contacting the Mn +4 doped phosphor at an elevated temperature with fluorine gas to form the color stable Mn +4 doped phosphor of formula I; wherein

A is Li, Na, K, Rb, Cs, 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;

x is the absolute value of the charge of the [MF y ] ion; and

y is 5, 6 or 7.

9. A process according to claim 8 , additionally comprising adding a third feed comprising a source of A to the reactor.

Assignments (11)