Phosphor, light emitting device using phosphor, and display and lighting system using light emitting device

1. A phosphor comprising a host material composed of a compound having a garnet crystal structure represented by the general formula (I):

M 1 a M 2 b M 3 c O d   (I)

wherein M 1 is a divalent metal element, M 2 is a trivalent metal element, M 3 is a tetravalent metal element containing at least Si, a is the number of 2.7 to 3.3, b is the number of 1.8 to 2.2, c is the number of 2.7 to 3.3, and d is the number of 11.0 to 13.0; and

Ce as a luminescent center ion and in addition to Ce at least one element selected from the group consisting of Cr, Mn, Fe, Co, Ni, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb are incorporated in said host material.

2. A phosphor according to claim 1 , wherein the tetravalent metal element M 3 contains Si in an amount of not less than 50 mol%.

3. A phosphor according to claim 1 , wherein the divalent metal element M 1 in the formula (I) is at least one element selected from the group consisting of Mg, Ca, Zn, Sr, Cd and Ba.

4. A phosphor according to claim 1 , wherein the divalent metal element M 1 in the formula (I) is Mg, Ca or Zn.

5. A phosphor according to claim 1 , wherein the trivalent metal element M 2 in the formula (I) is at least one element selected from the group consisting of Al, Sc, Ga, Y, In, La, Gd and Lu.

6. A phosphor according to claim 1 , wherein the trivalent metal element M 2 in the formula (I) is Al, Sc, Y or Lu.

7. A phosphor according to claim 1 , wherein the tetravalent metal element M 3 other than Si in the formula (I) is at least one element selected from the group consisting of Ti, Ge, Zr, Sn and Hf.

8. A phosphor according to claim 1 , wherein the tetravalent metal element M 3 other than Si in the formula (I) is at least one element selected from the group consisting of Ti, Zr, Sn and Hf.

9. A phosphor according to claim 1 , wherein the tetravalent metal element M 3 other than Si in the formula (I) is Ge or Sn.

10. A phosphor according to claim 1 , wherein in addition to Ce as the luminescent center ion at least one element selected from the group consisting of Mn, Fe, Co, Ni, Cu, Pr, Sm, Eu, Tb, Dy, and Yb is contained as the luminescent center ion.

11. A phosphor according to claim 1 , wherein the luminescent Ce center ion is trivalent Ce.

12. A phosphor according to claim 1 , wherein in the formula (1), the divalent metal element M 1 is Ca, the trivalent metal element M 2 is Sc, and the tetravalent metal element M 3 is Si.

13. A phosphor according to claim 1 , wherein in the formula (1), the divalent metal element M 1 is Ca and Mg, the trivalent metal element M 2 is Sc and Y, or Sc and Lu, and the tetravalent metal element M 3 is Si.

14. A phosphor according to claim 1 , wherein the amount of the luminescent center ion is 0.0001 to 0.3 mol based on a formula weight of the host material compound.

15. A phosphor according to claim 1 , wherein when a light emitted therefrom is represented by an XYZ color system and a sum of color coordinates x and y is not less than 0.6.

16. A phosphor according to claim 1 , wherein a brightness keeping percentage of said phosphor is not less than 90%.

17. A light emitting device comprising the phosphor as claimed in claim 1 as a wavelength conversion material, and a semiconductor light emitting element capable of emitting a light in the range of from ultraviolet light to visible light.

18. A light emitting device according to claim 17 , further comprising at least one additional phosphor.

19. A light emitting device according to claim 17 , wherein a general color rendering index Ra of a light emitted from the light emitting device is not less than 80, and a special color rendering index R 5 thereof is not less than 90.

20. A display using the light emitting device as claimed in claim 17 as a light source.

21. A lighting system using the light emitting device as claimed in claim 17 as a light source.