Processes for preparing color stable manganese-doped complex fluoride phosphors
View Patent ↗A process for preparing a color stable Mn 4+ doped complex fluoride phosphor of formula I includes A x (M (1−m) , Mn m )F y (I) contacting a first aqueous HF solution comprising (1−m) parts of a compound of formula H x MF y , and a second aqueous HF solution comprising m*n parts of a compound of formula A x [MnF y ], with a third aqueous HF solution comprising (1−n) parts of the compound of formula A x [MnF y ] and a compound of formula A a X, to yield a precipitate comprising the color stable Mn 4+ doped complex fluoride phosphor; wherein A is Li, Na, K, Rb, Cs, NR 4 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; R is H, lower alkyl, or a combination thereof; X is an anion; a is the absolute value of the charge of the X anion; x is the absolute value of the charge of the [MF y ] ion; y is 5, 6 or 7; 0<m≦0.05; 0.1≦n≦1.
1. A process for preparing a color stable Mn 4+ doped complex fluoride of formula I,
A x (M (1−m) , Mn m )F y (I)
the process comprising contacting a first aqueous HF solution comprising (1−m) parts of a compound of formula H x MF y , and
a second aqueous HF solution comprising m*n parts of a compound of formula A x [MnF y ], with a third aqueous HF solution comprising (1−n) parts of the compound of formula A x [MnF y ] and a compound of formula A a X,
to yield a precipitate comprising the color stable Mn 4+ doped complex fluoride;
wherein
A is Li, Na, K, Rb, Cs, NR 4 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;
R is H, lower alkyl, or a combination thereof;
X is an anion;
a is the absolute value of the charge of the X anion;
x is the absolute value of the charge of the [MF y ] ion;
y is 5, 6 or 7;
0<m≦0.05;
0.1≦n≦1.
2. A process according to claim 1 , wherein n ranges from 0.25 to 0.95.
3. A process according to claim 1 , wherein n ranges from 0.5 to 0.9.
4. A process according to claim 1 , wherein n ranges from 0.6 to 0.8.
5. A process according to claim 1 , wherein n is about 0.7.
6. A process according to claim 1 , wherein the Mn 4+ doped complex fluoride of formula I is K 2 (Si (1−m) , Mn m )F 6 .
7. A process according to claim 1 , wherein the salt of formula A a X is selected from KF, KHF 2 , and combinations thereof.
8. A process according to claim 1 , wherein the first and second aqueous HF solutions are added gradually to the third solution.
9. A process according to claim 1 , additionally comprising precipitating the compound of formula A x MnF y from a concentrated aqueous HF solution, and isolating the precipitate, prior to the contacting step.
10. An LED lighting apparatus comprising a complex fluoride prepared by the process of claim 1 .
11. An LED lighting apparatus comprising an LED chip; and a complex fluoride prepared by the process of claim 1 , disposed on a surface of the LED chip.
12. A process for preparing a color stable Mn 4+ , doped complex fluoride phosphor of formula K 2 (Si (1−m) , Mn m )F 6 ,the process comprising
contacting a first aqueous HF solution comprising (1−m) parts of a compound of formula H 2 SiF 6 ,and
a second aqueous HF solution comprising m*n parts of a compound of formula K 2 MnF 6 , with a third aqueous HF solution comprising (1−n) parts of the compound of formula K 2 MnF 6 and a compound selected from KF, KHF 2 , and combinations thereof;
to yield a precipitate comprising the color stable Mn 4+ , doped complex fluoride,
wherein
0<m≦0.08; and
0.1≦n≦1.
13. A process according to claim 1 , wherein n ranges from 0.6 to 0.8.
14. A process according to claim 1 , additionally comprising, prior to the gradual addition step, precipitating the compound of formula K 2 (Si (1−m) , Mn m )F 6 from a concentrate aqueous HF solution, and isolating the precipitate.