Wavelength converting material for a light emitting device

1. A light emitting device comprising:

a light source; and

a luminescent material, the luminescent material, comprising:

RE 3 Ga 5−x−y A x SiO 14 :Cr y (RE=La, Nd, Gd, Yb, Tm; A=Al, Sc), where 0≤x≤1 and 0.005≤y≤0.1;

a host lattice crystallizing in a trigonal calcium gallogermanate structure type; and

dopants disposed in the host lattice, the dopants comprising:

trivalent chromium; and

tetravalent chromium in a concentration that is less than 1% of a total concentration of all chromium in the luminescent material.

2. The light emitting device of claim 1 , wherein the host lattice comprises a tetravalent cation with an effective atomic radius at least 10% smaller than an effective ionic radius of Cr(IV).

3. The light emitting device of claim 1 , wherein the host lattice is La 3 Ga 5−x SiO 14 .

4. The light emitting light emitting device of claim 1 , wherein the luminescent material is (La,Gd) 3 Ga 5−x−y Al x SiO 14 :Cr y , where 0≤x≤1 and 0.02≤y≤0.08.

5. The light emitting device of claim 1 wherein the luminescent material is La 2.98 Gd 0.02 Ga 4.76 Al 0.2 SiO 14 :Cr 0.04 .

6. A light emitting device comprising:

a light source; and

a luminescent material comprising RE 3 Ga 5−x−y A x SiO 14 :Cr y (RE=La, Nd, Gd, Yb, Tm; A=Al, Sc), where 0≤x≤1 and 0.005≤y≤0.1;

and a second luminescent material comprising at least one of:

Gd 3−x RE x Sc 2−y−z Ln y Ga 3−w Al w O 12 :Cr z (Ln=Lu, Y, Yb, Tm; RE=La, Nd), where 0≤x≤3; 0≤y≤1.5; 0≤z≤0.3; and 0≤w≤2;

AAEM 1−x F 6 :Cr x (A=Li, Cu; AE=Sr, Ca; M=Al, Ga, Sc) where 0.005≤x≤0.2; and

A 2−x (WO 4 ) 3 :Cr x (A=Al, Ga, Sc, Lu, Yb) where 0.003≤x≤0.5.

7. The light emitting device of claim 6 , wherein:

the second luminescent material is Gd 3−x1 Sc 2−x2−y Lu x1+x2 Ga 3 O 12 :Cr y , where 0.02≤x1≤0.25, 0.05≤x2≤0.3 and 0.04≤y≤0.12.

8. The light emitting device of claim 6 , wherein the second luminescent material is Gd 2.85 Sc 1.75 Lu 0.3 Ga 3 O 12 :Cr 0.1 .

9. The light emitting device of claim 6 , wherein the second luminescent material is Gd 2.8 La 0.2 Sc 1.7 Lu 0.2 Ga 3 O 12 :Cr 0.1 .

10. The light emitting device of claim 6 , wherein the second luminescent material is Gd 2.85 Sc 1.75 Lu 0.3 Ga 3 O 12 :Cr 0.1 .

11. The light emitting device of claim 6 , wherein the second luminescent material is SrLiAl 0.995 F 6 :Cr 0.1 .

12. A wavelength converting structure comprising:

a matrix;

a first luminescent material comprising RE 3 Ga 5−x−y A x SiO 14 :Cr y (RE=La, Nd, Gd, Yb, Tm; A=Al, Sc), where 0≤x≤1 and 0.005≤y≤0.1; and

a second luminescent material comprising at least one of a chromium doped garnet material, a chromium doped colquiirite material, and a chromium doped tungstate material.

13. The wavelength converting structure of claim 12 , wherein the second luminescent material comprises at least one of:

Gd 3−x RE x Sc 2−y−z Ln y Ga 3−w Al w O 12 :Cr z (Ln=Lu, Y, Yb, Tm; RE=La, Nd), where 0≤x≤3; 0≤y≤1.5; 0≤z≤0.3; and 0≤w≤2;

AAEM 1−x F 6 :Cr x (A=Li, Cu; AE=Sr, Ca; M=Al, Ga, Sc) where 0.005≤x≤0.2; and

A 2−x (WO 4 ) 3 :Cr x (A=Al, Ga, Sc, Lu, Yb) where 0.003≤x≤0.5.

14. The wavelength converting structure of claim 12 , wherein the first luminescent material comprises a host lattice crystallizing in a trigonal calcium gallogermanate structure type and dopants disposed in the host lattice, the dopants comprising:

trivalent chromium; and

tetravalent chromium in a concentration that is less than 10% of a total concentration of all chromium in the first luminescent material.

15. The wavelength converting structure of claim 12 , wherein the matrix comprises at least one of glass, ceramic, and silicone.

16. The wavelength converting structure of claim 12 , wherein the matrix is formed into a tile.

17. The wavelength converting structure of claim 12 , wherein the matrix is formed into a flexible sheet.