Red-emitting phosphors, processes and devices
A process for synthesizing a Mn 4+ doped phosphor of formula I by electrolysis is presented. The process includes electrolyzing a reaction solution comprising a source of manganese, a source of M and a source of A. One aspect relates to a phosphor composition produced by the process. A lighting apparatus including the phosphor composition is also provided. A x [MF y ]:Mn 4+ (I) where, 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.
1. A process for synthesizing a Mn 4+ doped phosphor of formula I:
A X [MF y ]:Mn 4+ (I)
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;
the method comprising electrolyzing a reaction solution comprising a source of manganese dissolved in at least one of hydrofluoric acid and hexafluorosilicic acid, a source of M and a source of A, wherein electrolyzing further comprises:
passing an electric current through the reaction solution comprising the source of manganese and at least one of hydrofluoric acid and hexafluorosilicic acid to form an electrolyzed manganese solution,
combining the source of M and the source of A with the electrolyzed manganese solution to form a combined solution; and
passing an electric current through the combined solution.
2. The process according to claim 1 , wherein the source of manganese is a compound comprising Mn 2+ , Mn 3+ , Mn 4+ , Mn 5+ , Mn 6+ or a combination thereof.
3. The process according to claim 1 , wherein the source of manganese is MnF 2 , MnF 3 , MnCl 3 , MnCl 2 , MnO 2 or a combination thereof.
4. The process according to claim 1 , wherein M is Si, Ge, Ti, or a combination thereof.
5. The process according to claim 1 , wherein the source of M is H 2 SiF 6 , A 2 SiF 6 , SiO 2 , SiCl 4 , Si(OAc) 4 or a combination thereof.
6. The process according to claim 1 , wherein the source of A is AF, ACl, AOCH 3 , A 2 C 2 O 4 , AH 2 PO 4 , or a combination thereof.
7. The process according to claim 1 , wherein the source of A is KF, KHF 2 , or a combination thereof.
8. The process according to claim 1 , wherein the Mn 4+ doped phosphor of formula I is A 2 [MF 6 ]:Mn 4+ , wherein A is Li, Na, K, Rb, Cs, or a combination thereof; and M is Si, Ge, Ti, or a combination thereof.
9. The process according to claim 1 , wherein the Mn 4+ doped phosphor of formula I is K 2 SiF 6 :Mn 4+ .