Moisture-resistant phosphor compositions and associate methods
A phosphor composition is derived from combining K 2 SiF 6 :Mn 4+ in solid form with a saturated solution of a manganese-free complex fluoride including a composition of formula I: A 3 [MF 6 ], where A is selected from Na, K, Rb, and combinations thereof and M is selected from Al, Ga, In, Sc, Y, Gd, and combinations thereof. The composition of formula I: A 3 [MF 6 ] has a water solubility lower than a water solubility of K 2 SiF 6 . A lighting apparatus including the phosphor composition is also provided.
1. A phosphor composition comprising particles of K 2 SiF 6 :Mn 4+ coated with a manganese-free complex fluoride comprising a composition of formula I: A 3 [MF 6 ], where A is selected from Na, K, Rb and combinations thereof; and M is selected from Al, Ga, In, Sc, Y, Gd and combinations thereof,
wherein the manganese-free complex fluoride further comprises K 2 SiF 6 in an amount less than about 50 weight percent, by weight of the manganese-free fluoride, and
wherein the composition of formula I: A 3 [MF 6 ] has lower water solubility than a water solubility of K 2 SiF 6 .
2. The phosphor composition of claim 1 , wherein the manganese-free complex fluoride is of formula I: A 3 [AlF 6 ], where A is selected from Na, K, and combinations thereof.
3. A phosphor composition comprising particles of K 2 SiF 6 :Mn 4+ coated with a manganese-free complex fluoride comprising a composition of formula I: A 3 [MF 6 ],
where A is selected from Na, K, Rb and combinations thereof; and M is selected from Al, Ga, In, Sc, Y, Gd and combinations thereof,
wherein the composition of formula I: A 3 [MF 6 ] has lower water solubility than a water solubility of K 2 SiF 6 , wherein the compositions of formula I: A 3 [MF 6 ] having a solubility in water lower than a solubility of K 2 SiF 6 in water, are K 3 AlF 6 , and K 2 NaAlF 6 .
4. A lighting apparatus comprising:
a light source; and
a phosphor composition radiationally coupled to the light source, the phosphor composition comprising particles of K 2 SiF 6 :Mn 4+ coated with a manganese-free complex fluoride comprising a composition of formula I: A 3 [MF 6 ], where A is selected from Na, K, Rb, and combinations thereof; and M is selected from Al, Ga, In, Sc, Y, Gd and combinations thereof, wherein the composition of formula I: A 3 [MF 6 ] has lower water solubility than a water solubility of K 2 SiF 6 ;
wherein the phosphor composition further comprises at least one of a garnet activated with Ce 3+ , an alkaline earth orthosilicate activated with Eu 2+ , or (Sr,Ca,Ba) 3 (Si,Al)O 4 (F,O) activated with Ce 3+ .
5. The lighting apparatus of claim 4 , wherein the manganese-free complex fluoride comprises a composition of formula I: A 3 [AlF 6 ], where A is selected from Na, K, and combinations thereof.
6. The lighting apparatus of claim 4 , wherein the light source is a semiconductor light emitting diode (LED) which emits radiation having a peak wavelength in the range of from about 370 to about 500 nm.
7. The lighting apparatus of claim 4 , further comprising an encapsulant material surrounding the light source and the phosphor composition within a housing.
8. The lighting apparatus of claim 4 , wherein the phosphor composition is disposed on a surface of the light source.
9. The lighting apparatus of claim 7 , wherein the phosphor composition is dispersed in the encapsulant material.
10. A method, comprising:
combining a saturated solution of a manganese-free complex fluoride comprising a composition of formula I: A 3 [MF 6 ], where A is selected from Na, K, Rb, and combinations thereof; and M is selected from Al, Ga, In, Sc, Y, Gd and combinations thereof, with K 2 SiF 6 :Mn 4+ phosphor in solid form to form a slurry, wherein the composition of formula I: A 3 [MF 6 ] has a water solubility lower than a water solubility of K 2 SiF 6 ;
filtering the slurry; and
isolating a product from the slurry; wherein the manganese-free complex fluoride further comprises K 2 SiF 6 in an amount less than about 50 weight percent, by weight of the manganese-free fluoride.
11. The method of claim 10 , wherein preparing the saturated solution comprises preparing the saturated solution in an acid selected from the group consisting of at least HF, HCI, NH 4 HF2, and NH 4 F.
12. The method of claim 10 , wherein combining comprises pouring the saturated solution onto K 2 SiF 6 :Mn 4+ in solid form in the vessel with continuous stirring.
13. The method of claim 10 , wherein isolating the product comprises drying the slurry.
14. A phosphor composition derived from combining K 2 SiF 6 :Mn 4+ in solid form with a saturated solution of a manganese-free complex fluoride comprising a composition of formula I: A 3 [MF 6 ], where A is selected from Na, K, Rb, and combinations thereof; and M is selected from Al, Ga, In, Sc, Y, Gd, and combinations thereof,
wherein the composition of formula I: A 3 [MF 6 ] has a water solubility lower than a water solubility of K 2 SiF 6 ;
wherein the compositions of formula I: A 3 [MF 6 ] having a solubility in water lower than a solubility of K 2 SiF 6 in water, are K 3 AlF 6 , and K 2 NaAlF 6 .
15. The phosphor composition of claim 14 , wherein the manganese-free complex fluoride comprises a composition of formula I: A 3 [AlF 6 ], where A is selected from Na, K, and combinations thereof.
16. The phosphor composition of claim 14 , wherein the manganese-free complex fluoride further comprises K 2 SiF 6 in an amount less than about 50 weight percent, by weight of the manganese-free fluoride.