Green-emitting, garnet-based phosphors in general and backlighting applications
Disclosed herein are green-emitting, garnet-based phosphors having the formula (Lu 1-a-b-c Y a Tb b A c ) 3 (Al 1-d B d ) 5 (O 1-e C e ) 12 : Ce,Eu, where A is selected from the group consisting of Mg, Sr, Ca, and Ba; B is selected from the group consisting of Ga and In; C is selected from the group consisting of F, Cl, and Br; and 0≦a≦1; 0≦b≦1; 0<c≦0.5; 0≦d≦1; and 0<e≦0.2. These phosphors are distinguished from anything in the art by nature of their inclusion of both an alkaline earth and a halogen. Their peak emission wavelength may lie between about 500 nm and 540 nm; in one embodiment, the phosphor (Lu,Y,A) 3 Al 5 (O,F,Cl) 12 : Eu 2+ has an emission at 540 nm. The FWHM of the emission peak lies between 80 nm and 150 nm. The present green garnet phosphors may be combined with a red-emitting, nitride-based phosphor such as CaAlSiN 3 to produce white light.
1. A cerium-activated, green-emitting lutetium aluminate phosphor comprising lutetium, cerium aluminum, oxygen, fluorine, and strontium, wherein said phosphor is configured to absorb excitation radiation having a wavelength ranging from about 380 nm to about 480 nm, and to emit light having a peak emission wavelength ranging from about 523.44 nm to about 534.64 nm, wherein said phosphor is characterized by CIE(x) coordinates ranging from 0.3405 to 0.3677 and CIE(y) coordinates ranging from 0.5718 to 0.5748.
2. The cerium-activated, green-emitting lutetium aluminate phosphor of claim 1 , wherein phosphor particle size is characterized by a particle size distribution with D50 ranging from about 3.84 microns to 11.38 microns.
3. A cerium-activated, green-emitting lutetium aluminate phosphor comprising lutetium, cerium, aluminum, oxygen, fluorine, and magnesium, wherein said phosphor is configured to absorb excitation radiation having a wavelength ranging from about 380 nm to about 480 nm, and to emit light having a peak emission wavelength ranging from about 514.22 nm to about 529.56 nm, wherein said phosphor is characterized by CIE(x) coordinates ranging from 0.3336 to 0.3635 and CIE(y) coordinates ranging from 0.5776 to 0.5862.
4. The cerium-activated, green-emitting lutetium aluminate phosphor of claim 3 , wherein phosphor particle size is characterized by a particle size distribution with D50 ranging from about 4.01 microns to 9.30 microns.
5. The cerium-activated, green-emitting lutetium aluminate phosphor of claim 3 , wherein said excitation radiation has a wavelength ranging from about 420 nm to about 480 nm.
6. A white LED comprising:
a radiation source configured to provide radiation having a wavelength greater than about 280 nm;
a cerium-activated, green-emitting lutetium aluminate phosphor comprising lutetium, cerium, aluminum, oxygen, fluorine, and strontium, wherein said phosphor is configured to absorb excitation radiation having a wavelength ranging from about 380 nm to about 480 nm, and to emit light having a peak emission wavelength ranging from about 523.44 nm to about 534.64 nm, wherein said phosphor is characterized by CIE(x) coordinates ranging from 0.3405 to 0.3677 and CIE(y) coordinates ranging from 0.5718 to 0.5748; and
at least one of a red-emitting phosphor or a yellow-emitting phosphor.
7. The white LED of claim 6 , wherein the red-emitting phosphor is a nitride.
8. The white LED of claim 7 , wherein the nitride has the formula (Ca,Sr)AlSiN 3 :Eu 2+ .
9. The white LED of claim 6 , wherein the yellow-emitting phosphor is a silicate.
10. The white LED of claim 9 , wherein the silicate has the formula (Sr,Ba) 2 SiO 4 :Eu 2+ .
11. The cerium-activated, green-emitting lutetium aluminate phosphor of claim 1 , wherein said excitation radiation has a wavelength ranging from about 420 nm to about 480 nm.
12. A white LED comprising:
a radiation source configured to provide radiation having a wavelength greater than about 280 nm;
a cerium-activated, green-emitting lutetium aluminate phosphor comprising lutetium, cerium, aluminum, oxygen, fluorine, and magnesium, wherein said phosphor is configured to absorb excitation radiation having a wavelength ranging from about 380 nm to about 480 nm, and to emit light having a peak emission wavelength ranging from about 514.22 nm to about 529.56 nm, wherein said phosphor is characterized by CIE(x) coordinates ranging from 0.3336 to 0.3635 and CIE(y) coordinates ranging from 0.5776 to 0.5862; and
at least one of a red-emitting phosphor or a yellow-emitting phosphor.
13. The white LED of claim 12 , wherein the red-emitting phosphor is a nitride.
14. The white LED of claim 13 , wherein the nitride has the formula (Ca,Sr)AlSiN 3 :Eu 2+ .
15. The white LED of claim 12 , wherein the yellow-emitting phosphor is a silicate.
16. The white LED of claim 15 , wherein the silicate has the formula (Sr,Ba) 2 SiO 4 :Eu 2+ .