Phosphors with narrow green emission
A luminescent composition of matter is characterized by the formula REM 2+x E y , where RE may be one or more Rare Earth elements (for example, Eu or Gd), M may be one or more elements selected from the group Al, Ga, B, In, Sc, Lu, and Y; E is one or more elements selected from the group S, Se, O, and Te; x is greater than zero; and y has the value that achieves charge balance in the formula assuming that E has a charge of −2.
1. A luminescent composition of matter characterized by the formula REM 2+x E y , wherein:
RE is one or more rare earth elements;
M is one or more elements selected from the group Al, Ga, B, In, Sc, Lu, and Y;
E is one or more elements selected from the group S, Se, O, and Te;
x is greater than or equal to 0.1 and less than or equal to 0.9; and
y has the value that achieves charge balance in the formula assuming that E has a charge of −2.
2. The luminescent composition of matter of claim 1 , wherein x is greater than or equal to 0.3.
3. The luminescent composition of matter of claim 1 , wherein x is greater than or equal to 0.7.
4. The luminescent composition of matter of claim 1 , having exclusively an EuM 2 E 4 pseudoorthorhombic crystal structure.
5. The luminescent composition of matter of claim 1 , having a mixture of predominantly an EuM 2 E 4 pseudoorthorhombic crystal structure and one or more binary chalcogenide crystal structures.
6. The luminescent composition of matter of claim 1 , wherein RE is Eu.
7. The luminescent composition of matter of claim 6 , wherein x is greater than or equal to 0.3.
8. The luminescent composition of matter of claim 6 , wherein x is greater than or equal to 0.7.
9. The luminescent composition of matter of claim 6 , having exclusively an EuM 2 E 4 . pseudoorthorhombic crystal structure.
10. The luminescent composition of matter of claim 6 , having a mixture of predominantly an EuM 2 E 4 pseudoorthorhombic crystal structure and one or more binary chalcogenide crystal structures.
11. The luminescent composition of matter of claim 1 , wherein RE comprises Eu and Gd.
12. The luminescent composition of matter of claim 11 , wherein x is greater than or equal to 0.3.
13. The luminescent composition of matter of claim 11 , wherein x is greater than or equal to 0.7.
14. The luminescent composition of matter of claim 1 , wherein the composition is characterized by the formula Eu(Al,Ga) 2+x S y .
15. The luminescent composition of matter of claim 14 , wherein the ratio of Al to Ga is between about 1:3 and about 2:1.
16. The luminescent composition of matter of claim 14 , wherein x is greater than or equal to 0.3.
17. The luminescent composition of matter of claim 14 , wherein x is greater than or equal to 0.7.
18. The luminescent composition of matter of claim 14 , having exclusively an EuM 2 E 4 . pseudoorthorhombic crystal structure.
19. The luminescent composition of matter of claim 14 , having a mixture of predominantly an EuM 2 E 4 pseudoorthorhombic crystal structure and one or more binary chalcogenide crystal structures.
20. The luminescent composition of matter of claim 17 wherein the composition is characterized by the formula EuAl 1.08 Ga 1.02 S 5.05 .
21. The luminescent composition of matter of claim 1 , wherein the composition is characterized by the formula EuAl 2+x E y . where E is selected from the group S and Se.
22. The luminescent composition of matter of claim 21 , wherein x is greater than or equal to 0.3.
23. The luminescent composition of matter of claim 21 , wherein x is greater than or equal to 0.7.
24. The luminescent composition of matter of claim 21 , having exclusively an EuM 2 E 4 . pseudoorthorhombic crystal structure.
25. The luminescent composition of matter of claim 21 , having a mixture of predominantly an EuM 2 E 4 pseudoorthorhombic crystal structure and one or more binary chalcogenide crystal structures.
26. The luminescent composition of matter of claim 21 , wherein the composition is characterized by the formula EuAl 2.7 Se 5.05 .
27. The luminescent composition of matter of claim 21 , wherein the composition is characterized by the formula EuAl 2.7 S 5.05 .
28. A light emitting device comprising:
a light emitting diode emitting light over a first wavelength range; and
a luminescent composition of matter arranged to be excited by emission from the light emitting diode and in response emit light over a second wavelength range;
wherein the luminescent composition of matter is characterized by the formula REM 2+x E y , wherein:
RE is one or more rare earth elements;
M is one or more elements selected from the group Al, Ga, B, In, Sc, Lu, and Y;
E is one or more elements selected from the group S, Se, O, and Te;
x is greater than or equal to zero and less than or equal to 0.9; and
y has the value that achieves charge balance in the formula assuming that E has a charge of −2.
29. The light emitting device of claim 28 , wherein RE is Eu and x is greater than or equal to 0.3.
30. The light emitting device of claim 28 , wherein RE is Eu and x is greater than or equal to 0.7.