Wavelength converting material for a light emitting device

1. A wavelength converting material comprising R 3-x-y-z A x+y M z Si 6-w1 Al w1 O 3x+y+w1 N 11-7x/3-y-w1 □ 2-2x/3 ,

the wavelength converting material comprising a crystal lattice;

□ representing a vacancy in the crystal lattice;

0<x≤3;

−3≤y<3;

0<z<1;

0≤w1≤6;

0≤x+y, x+y+z≤3;

11−7/3x−y−w1≥0;

3x+y+w1≤13;

R is selected from a group trivalent La, Gd, Tb, Y, and Lu;

A is selected from a group bivalent Ca, Mg, Sr, Ba, and Eu;

M is selected from a group trivalent Ce, Pr and Sm;

at least one of the vacancies □ occupied by an O atom,

[La]>0,

[Ca]>0,

0≤[Eu]≤0.01, and

([La]+[Ca]+[Ce]+[Eu])/[Si]≤0.52.

2. The wavelength converting material according to claim 1 , wherein the wavelength converting material comprises SiAlON.

3. The wavelength converting material according to claim 1 , wherein R=La a (Y b Lu 1-b ) 1-a , where a≥0.5, 0≤b≤1.

4. The wavelength converting material according to claim 1 , further comprising Y and Sr.

5. The wavelength converting material according to claim 1 , wherein no more than 5% of Si is replaced by Al.

6. The wavelength converting material according to claim 1 , further comprising La, Ca, and O.

7. A device comprising:

a light emitting diode that emits blue light; and

a wavelength converting material according to claim 1 disposed in a path of the blue light.

8. The device according to claim 7 wherein:

the wavelength converting material comprises Ce; and

([La]+[Ca]+[Ce])/[Si]≤0.52.

9. The device according to claim 7 , wherein the wavelength converting material is a first wavelength converting material that emits light having a peak wavelength that is yellow or green, the device further comprising a second wavelength converting material that emits light having a peak wavelength that is red.