Silicate-based phosphors and LED lighting devices using the same

1. A phosphor of formula I:

M 2 (SiO 4 ) 1-x-y-z (TiO 4 ) x (ZrO 4 ) y (HfO 4 ) z :A,S

wherein M is one or more divalent metal ions; A is one or more activators; S is one or more co-activators; and 0<x, y, z<1 and x+y+z<1.

2. The phosphor of claim 1 , wherein the phosphor is encapsulated with at least one layer of a coating comprising at least one product of hydrolysis of a metal or semiconductor alkoxide, metal alkyl, or metal or semiconductor tetrachloride.

3. The phosphor of claim 2 , wherein the phosphor maintains at least about 80% of its original optical performance after exposure for about 2000 hours to a temperature of about 85° C. and a relative humidity of about 85%.

4. The phosphor of claim 2 , wherein the product of hydrolysis of a metal or semiconductor alkoxide, metal alkyl, or metal or semiconductor tetrachloride is selected from the group consisting of titanium oxide, aluminum oxide, zirconium oxide, tin oxide, boron oxide, silicon oxide, zinc oxide, germanium oxide, tantalum oxide, niobium oxide, hafnium oxide, gallium oxide, aluminum silicate and combinations thereof.

5. The phosphor of claim 2 , wherein the coating has a thickness of from about 0.005 microns to about 3.0 microns.

6. The phosphor of claim 1 , wherein M is selected from the group consisting of Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Zn 2+ , Cd 2+ and combinations thereof.

7. The phosphor of claim 1 , wherein A is selected from the group consisting of divalent rare earth metal ions, trivalent metal ions and mixtures thereof.

8. The phosphor of claim 7 , wherein A is a divalent rare earth metal ion selected from the group consisting of Eu 2+ and Yb 2+ and mixtures thereof.

9. The phosphor of claim 7 , wherein A is a trivalent metal ion selected from the group consisting of Bi 3+ , Al 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ , Yb 3+ and Lu 3+ and mixtures thereof.

10. The phosphor of claim 1 , wherein S is selected from the group consisting of monovalent metal ion, halogen ions and mixtures thereof.

11. The phosphor of claim 9 , wherein S is a monovalent metal ion selected from the group consisting of Li + , Na + , K + , Rb + , Cu + , Ag + and mixtures thereof.

12. The phosphor of claim 10 , wherein S is a halogen ion selected from the group consisting of F − , Cl − , Br − , I − and mixtures thereof.

13. The phosphor of claim 1 , wherein the phosphor has a formula selected from the group consisting of:

a. (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , H − , wherein H − , is one or more halogen ions;

b. (Ca x Sr 1-x ) 2 (SiO 4 ): Eu 2+ , Pr 3+ , A, wherein A is one or more monovalent ions;

c. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Dy 3+ , H − , wherein H − is one or more halogen ions;

d. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Yb 2+ , H − , wherein H − is one or more halogen ions;

e. (Ca x Sr 1-x ) 2 (SiO 4 ) 1-x-y (ZrO 4 ) y :Eu 2+ , H − , wherein H − is one or more halogen ions; and

f. (Ca x Sr 1-x ) 2 (SiO 4 ) 1-x-z (HfO 4 ) z :Eu 2+ , H − , wherein H − is one or more halogen ions.

14. The phosphor of claim 13 , wherein the phosphor has a formula of (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , H − , wherein H − is one or more halogen ions.

15. The phosphor of claim 14 , wherein the phosphor has a formula selected from the group consisting of:

g. (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , Li + ;

h. (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , Cl − ;

i. (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , Br − ;

j. (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , I − ;

k. (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , (Cl − , I − );

l. (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , (Cl − , Br − ; and

m. (Ca x Sr 1-x ) 2 (SiO 4 ):Ce 3+ , Eu 2+ , (Br − , I − ).

16. The phosphor of claim 13 , wherein the phosphor has a formula of (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Pr 3+ , A, wherein A is one or more monovalent ions.

17. The phosphor of claim 16 , wherein the phosphor has a formula selected from the group consisting of:

n. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Pr 3+ , Li + ;

o. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Pr 3+ , Cl − ;

p. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Pr 3+ , Br − ;

q. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Pr 3+ , I − ;

r. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Pr 3+ , (Cl − , I − );

s. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Pr 3+ , (Cl − , Br − ); and

t. (Ca x Sr 1-x ) 2 (SiO 4 ):Eu 2+ , Pr 3+ , (Br − , I − ).

18. The phosphor of claim 1 , wherein the phosphor has a band emission of greater than about 120 nm.

19. The phosphor of claim 1 , wherein the phosphor emits light in a wavelength of from about 500 nm to about 600 nm.