Narrow band emitting SiAION phosphor
This specification discloses methods of enhancing the stability and performance of Eu 2+ doped narrow band red emitting phosphors. In one embodiment the resulting phosphor compositions are characterized by crystallizing in ordered structure variants of the UCr 4 C 4 crystal structure type and having a composition of AE 1−x Li 3−2y Al 1+y−z Si z O 4−4y−z N 4y+z :Eu x (AE=Ca, Sr, Ba, or a combination thereof, 0<x<0.04, 0≤y<1, 0<z<0.05, y+z≤1). It is believed that the formal substitution (Al,O) + by (Si,N) + reduces the concentration of unwanted Eu 3+ and thus enhances properties of the phosphor such as stability and conversion efficiency.
1. A luminescent composition of matter characterized by the formula:
AE 1−x Li 3−2y Al 1+2y−z Si z O 4−4y−z N 4y+z :Eu x ;
AE=Ca,Sr,Ba, or a combination thereof;
0<x<0.04;
0.4<y<0.6; and
0<z<0.05,
the luminescent composition of matter having a tetragonal crystal structure.
2. The luminescent composition of matter of claim 1 , wherein y is equal to or about equal to 0.5.
3. The luminescent composition of matter of claim 1 characterized by the formula AE 1−x Li 2 Al 2-z Si z O 2-z N 2+z :Eu x .
4. The luminescent composition of matter of claim 3 , wherein AE=Sr.
5. The luminescent composition of matter of claim 1 characterized by the formula:
Sr 0.995-q Ba q Li 2 Al 1.995 Si 0.005 O 1.995 N 2.005 :Eu 0.005 ;
q>0.
6. The luminescent composition of matter of claim 1 , wherein the crystal structure is a variant of the UCr 4 C 4 type structure.
7. The luminescent composition of matter of claim 1 , emitting light with an emission peak having a peak wavelength in the range 612 nm to 620 nm and a full width at half maximum≤55 nm.
8. The luminescent composition of matter of claim 1 , wherein 1/5≤z/x≤8.
9. The luminescent composition of matter of claim 8 , wherein 1/5≤z/x≤4.
10. The luminescent composition of matter of claim 9 , wherein 1/2≤z/x≤3.
11. The luminescent composition of matter of claim 1 wherein y is equal to or about equal to 0.5, and the crystal structure is a variant of the UCr 4 C 4 type structure.
12. The luminescent composition of matter of claim 11 , emitting light with an emission peak having a peak wavelength in the range 612 nm to 620 nm and a full width at half maximum≤55 nm.
13. The luminescent composition of matter of claim 12 , wherein 1/5≤z/x≤8.
14. The luminescent composition of matter of claim 13 , wherein 1/5≤z/x≤4.
15. A method for making the luminescent composition of matter of claim 1 , comprising reacting Eu 2 Si 5 N 8 with additional reagents.
16. A light emitting device comprising:
a semiconductor light emitting device; and
a phosphor composition comprising the luminescent composition of matter of claim 1 positioned to absorb light emitted by the semiconductor light emitting device and in response emit light of a longer wavelength.
17. The light emitting device of claim 16 , wherein a combined light output from the semiconductor light emitting device and the phosphor composition is perceived as white by a human with normal color vision, where the combined light output is characterized by a CRI of 80 or greater.
18. An adaptive illumination system comprising:
an array of independently controllable pcLEDs at least some of which comprise the luminescent composition of matter of claim 1 ; and
a lens or lens system arranged to collimate or partially collimate light emitted by the pcLEDs.
19. A mobile device comprising:
a camera; and
a flash illumination system comprising:
a monolithic array of independently controllable pcLEDs at least some of which comprise the luminescent composition of matter of claim 1 ; and
a lens or lens system spaced apart from the array of LEDs and arranged to direct light emitted by the pcLEDs into a field of view of the camera.
20. A display system comprising:
a display;
a monolithic array of independently controllable pcLEDs at least some of which comprise the luminescent composition of matter of claim 1 ; and
a lens or lens system spaced apart from the array of LEDs and arranged to couple light from the array of LEDs into the display.