Yellow phosphor having an increased activator concentration and a method of making a yellow phosphor

1. A yellow phosphor having an increased activator concentration, the yellow phosphor comprising:

a host lattice comprising yttrium aluminum garnet (YAG); and

an activator comprising cerium (Ce) in the host lattice, the cerium being present at a concentration of at least about 5 wt. % Ce,

wherein the yellow phosphor has a chemical formula Y 3-x Ce x Al 5 O 12 .

2. The yellow phosphor of claim 1 , wherein the concentration is at least about 5.2 wt. % Ce.

3. The yellow phosphor of claim 1 , wherein the concentration is from about 5 wt. % Ce to about 6 wt. % Ce.

4. The yellow phosphor of claim 1 where 0.14≦x≦0.16.

5. The yellow phosphor of claim 1 comprising a ccx value of at least about 0.47.

6. The yellow phosphor of claim 5 , wherein the ccx value is from about 0.471 to about 0.474.

7. The yellow phosphor of claim 5 comprising a Δccx value of from about 0.01 to about 0.02, where the Δccx value is obtained by comparing the ccx value of the yellow phosphor with a ccx value from a reference yellow phosphor, the reference yellow phosphor being a YAG phosphor doped with about 4 wt. % Ce and containing no other dopant elements.

8. The yellow phosphor of claim 1 having a ccy value of less than 0.52.

9. The yellow phosphor of claim 8 , wherein the ccy value is from about 0.513 to about 0.515.

10. The yellow phosphor of claim 8 comprising a Δccy value of from about −0.005 to about −0.015, where the Δccy value is obtained by comparing the ccy value of the yellow phosphor with a ccy value from a reference yellow phosphor, the reference yellow phosphor being a YAG phosphor doped with about 4 wt. % Ce and containing no other detectible dopant elements.

11. A method of making a yellow phosphor, the method comprising:

forming a reaction mixture comprising:

a first precursor comprising cerium and oxygen;

a second precursor comprising cerium and fluorine;

a third precursor comprising yttrium; and

a fourth precursor comprising aluminum;

heating the reaction mixture in a reducing environment at a temperature sufficient to form a yellow phosphor including a host lattice comprising yttrium aluminum garnet and an activator comprising cerium (Ce) incorporated in the host lattice at a concentration of at least about 5 wt. %.

12. The method of claim 11 , wherein the first precursor comprises CeO 2 and the second precursor comprises CeF 3 .

13. The method of claim 11 , wherein a weight ratio of the first precursor to the second precursor is at least about 1:1.

14. The method of claim 13 , wherein the weight ratio is at least about 1.4:1.

15. The method of claim 14 , wherein the weight ratio is at least about 1.9:1.

16. The method of claim 11 , wherein the third precursor comprises Y 2 O 3 and the fourth precursor comprises γ-Al 2 O 3 .

17. The method of claim 11 , further comprising reducing an average particle size of the fourth precursor prior to forming the reaction mixture.

18. The method of claim 11 , wherein the reaction mixture is heated to a temperature ranging from about 1375° C. to about 1550° C.

19. The method of claim 11 , wherein forming the yellow phosphor comprises a liquid-phase diffusion mechanism.

20. A light emitting diode (LED) component comprising:

a blue LED comprising a dominant wavelength in a range of from about 425 nm to about 475 nm;

a yellow phosphor in optical communication with the blue LED, the yellow phosphor comprising a host lattice comprising yttrium aluminum garnet and an activator comprising cerium incorporated in the host lattice, the yellow phosphor having a chemical formula Y 3-x Ce x Al 5 O 12 ;

wherein a light emission spectrum of the LED component defines a color line passing through an E3 color bin on a CIE 1931 chromaticity diagram at a position below a center point thereof.

21. The LED component of claim 20 , wherein the color line passes through an E4 color bin.

22. The LED component of claim 21 , wherein the color line passes through 4B and 4C sub-bins.

23. The LED component of claim 20 , wherein the cerium is present at a concentration of at least about 5 wt. % Ce in the host lattice.

24. A light emitting diode (LED) component comprising:

a blue LED comprising a dominant wavelength in a range from about 425 nm to about 475 nm;

a yellow phosphor in optical communication with the blue LED, the yellow phosphor comprising a host lattice comprising yttrium aluminum garnet and an activator comprising cerium incorporated in the host lattice and further comprising a ccx value of at least about 0.47 and a ccy value of less than 0.52; and

a red phosphor in optical communication with the blue LED, the red phosphor comprising a peak emission wavelength in a range of from about 610 nm to about 660 nm,

wherein a weight ratio of the yellow phosphor to the red phosphor is greater than about 9.5.

25. The LED component of claim 24 , wherein the weight ratio is as high as about 9.9.

26. The LED component of claim 24 , wherein a light emission spectrum of the LED component defines a color line passing through an E5 bin on a CIE 1931 chromaticity diagram.

27. The LED component of claim 26 , wherein the color line further passes through an E6 bin on the CIE 1931 chromaticity diagram.

28. The LED component of claim 24 , wherein the cerium is present at a concentration of at least about 5 wt. % Ce in the host lattice.