Gallium-substituted yttrium aluminum garnet phosphor and light emitting devices including the same

1. A phosphor composition comprising:

a yttrium aluminum garnet (YAG) phosphor as a primary phosphor, the YAG phosphor comprising a YAG lattice, wherein gallium is substituted into the YAG lattice, and further comprising cerium as an activator, the cerium substituting into the YAG lattice, wherein R=(moles of cerium+moles of yttrium)/(moles of gallium+moles of aluminum) and 0.5<R<0.6, and

wherein the phosphor composition is present as particles having an average particle diameter in a range of 2 to 25 μm.

2. The phosphor composition of claim 1 , wherein

(moles of cerium)/(moles of cerium+moles of yttrium)=mol % Ce and 0<mol % Ce<10; and

(moles of gallium)/(moles of gallium+moles of aluminum)=mol % Ga and 0<mol % Ga<50.

3. The phosphor composition of claim 2 , wherein

2<mol % Ce<4;

10<mol % Ga<30; and

0.5<R≦0.57.

4. The phosphor composition of claim 1 , wherein the phosphor composition down-converts radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 500 nm to 570 nm.

5. The phosphor composition of claim 4 , further comprising a secondary phosphor such that the secondary phosphor down-converts radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 600 nm to 660 nm.

6. The phosphor composition of claim 5 , wherein the primary phosphor is about 50 to 100 weight percent of the total phosphor concentration.

7. The phosphor composition of claim 5 , wherein the secondary phosphor comprises a nitride and/or oxynitride phosphor.

8. The phosphor composition of claim 7 , wherein the secondary phosphor comprises (Ca 1-x Sr x )SiAlN 3 :Eu 2+ , where 0≦x≦1.

9. A light emitting device, comprising:

a solid state lighting source; and

a phosphor composition comprising a yttrium aluminum garnet (YAG) phosphor that has gallium substituted in the YAG phosphor,

wherein the YAG phosphor is also substituted with cerium, and

wherein R=(moles of cerium+moles of yttrium)/(moles of gallium+moles of aluminum) and 0.5<R<0.6.

10. The light emitting device of claim 9 , wherein the solid state lighting source comprises a Group III nitride light emitting source.

11. The light emitting device of claim 9 , wherein

(moles of cerium)/(moles of cerium+moles of yttrium)=mol % Ce and 0<mol % Ce<10; and

(moles of gallium)/(moles of gallium+moles of aluminum)=mol % Ga and 0<mol % Ga<50.

12. The light emitting device of claim 11 , wherein

2<mol % Ce<4;

10<mol % Ga<30; and

0.5<R≦0.57.

13. The light emitting device of claim 9 , wherein the phosphor composition down-converts radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 500 nm to 570 nm.

14. The light emitting device of claim 13 , wherein the phosphor composition further comprises a secondary phosphor such that the secondary phosphor down-converts radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 600 nm to 660 nm.

15. The light emitting device of claim 14 , wherein the primary phosphor is about 50 to 100 weight percent of the total phosphor concentration.

16. The light emitting device of claim 14 , wherein the secondary phosphor comprises a nitride or oxynitride phosphor.

17. The light emitting device of claim 16 , wherein the secondary phosphor comprises (Ca 1-x Sr x )SiAlN 3 :Eu 2+ , where 0≦x≦1.

18. The light emitting device of claim 9 , wherein the phosphor composition further comprises a binder.

19. The light emitting device of claim 9 , wherein the phosphor composition is present as particles having an average particle diameter in a range of 2 and 25 μm.

20. The light emitting device of claim 9 , further comprising a separate secondary phosphor composition such that the phosphor composition and the separate secondary phosphor composition together down-convert radiation having a peak wavelength in a range of 445 nm to 470 nm to radiation having a peak wavelength in a range of 600 nm to 660 nm.

21. The light emitting device of claim 9 , wherein the phosphor composition is present as a single crystal phosphor.

22. The light emitting device of claim 9 , wherein the phosphor composition down-converts at least some of the radiation emitted by the solid state lighting source to a radiation having a peak wavelength greater than 580 nanometers.

23. The light emitting device of claim 9 , wherein the phosphor composition down-converts at least some of the radiation emitted by the solid state lighting source to a radiation having a peak wavelength between 500 nanometers and 570 nanometers, and at least some of the radiation emitted by the solid state lighting source to a radiation having a peak wavelength between 600 nanometers and 660 nanometers.

24. The light emitting device of claim 9 , wherein the solid state lighting source comprises a light emitting diode that emits light having a dominant wavelength in the blue color range.

25. The light emitting device of claim 24 , wherein the dominant wavelength of the blue LED is between about 445 nm to 470 nm.

26. The light emitting device of claim 9 , wherein the light emitting device emits a warm white light having a correlated color temperature between about 2500K and 4500K.

27. The light emitting device of claim 26 , wherein the light emitting device emits a warm white light having a correlated color temperature between about 2500K and 3300K.

28. The light emitting device of claim 9 , wherein the light emitting device has a CRI value of at least 90.

29. The light emitting device of claim 9 , wherein the light emitted by the light emitting device has a color point that is within 7 MacAdam ellipses of the black-body locus on a 1931 CIE chromaticity diagram and has a correlated color temperature of between about 2500K and about 3300K.

30. The light emitting device of claim 9 , wherein the light emitting device has a CRI R9 component of greater than 50.