Red emitting luminescent materials
View Patent ↗The invention relates to an improved red light emitting material of the formula M 1−y A 1+x Si 4−x N 7−x−2y O x+2y :RE whereby M is selected out of the group comprising Ba, Sr, Ca, Mg or mixtures thereof, A is selected out of the group comprising Al, Ga, B or mixtures thereof, RE is selected out of the group comprising rare earth metals, Y, La, Sc or mixtures thereof and x is ≧0 and ≦1 and y is ≧0 and ≦0.2. This material is believed to crystallize in a novel structure type that comprises two individual lattice sites for rare 10 earth metal incorporation, which leads to an improved lighting behavior.
1. Light emitting device, comprising a LED comprising at least one material of the formula M 1−y A 1+x Si 4−x N 7−x−2y O x+2y :RE, whereby:
M is selected out of the group comprising Ba, Sr, Ca, Mg or mixtures thereof;
A is selected out of the group comprising Al, Ga, B or mixtures thereof;
RE is selected out of the group comprising rare earth metals, Y, La, Sc or mixtures thereof;
x is ≧0 and ≦1 and y is ≧0 and ≦0.2; and
the RE doping level is ≧0.05% and ≦10%;
wherein the LED emits blue light and the material emits red light, the device further comprising a phosphor that emits yellow light.
2. The material of claim 1 , whereby RE is selected out of the group comprising Eu, Ce or mixtures thereof.
3. The material of claim 1 , whereby the photostability of the material is ≧80%, preferably ≦90%.
4. The light emitting device of claim 1 whereby the at least one material is provided as powder and/or as ceramic material.
5. The light emitting device of claim 1 whereby the material is provided as a powder with a d 50 of ≧5 μm and ≦15 μm.
6. The light emitting device of claim 1 , whereby the material is provided as a ceramic having ≧90% of the theoretical density.
7. The light emitting device of claim 1 wherein the LED emits light at 440 to 460 nm.
8. The light emitting device of claim 1 wherein:
the LED emits light at 440 to 460 nm; and
the material is mixed with Y 3 Al 5 O 12 :Ce, suspended in a silicone resin, and deposited on top of the LED.
9. Material of the formula M 1−y A 1+x Si 4−x N 7−x−2y O x+2y :RE, whereby:
M is selected out of the group comprising Ba, Sr, Ca, Mg or mixtures thereof;
A is selected out of the group comprising Al, Ga, B or mixtures thereof;
RE is selected out of the group comprising rare earth metals, Y, La, Sc or mixtures thereof;
x is ≧0 and ≦1 and y is ≧0 and ≦0.2; and
the material is configured to emit red light.
10. Light emitting device, comprising a light emitting diode and at least one material according to claim 9 disposed in a path of light emitted by the light emitting diode.
11. The light emitting device of claim 10 wherein the light emitting diode emits blue light.