Phosphor, light emitting device using phosphor, and display and lighting system using light emitting device
View Patent ↗A phosphor (A) 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 a luminescent center ion incorporated in the host material; a light emitting device (B) comprising the phosphor 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; and a display (C) and a lighting system (D) using the light emitting device (B) as a light source. The above phosphor can be readily produced, and can provide a light emitting device having a high color rendering property.
1. A phosphor, comprising:
a host material comprising:
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 Ca and Mg,
M 2 is Sc,
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
trivalent Ce as a luminescent center ion incorporated in said host material, and
wherein a brightness keeping percentage of said phosphor is not less than 90%.
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 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.
4. 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.
5. A phosphor according to claim 1 , wherein the tetravalent metal element M 3 other than Si in the formula (I) is Ge or Sn.
6. 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.
7. 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.
8. 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.
9. A light emitting device according to claim 8 , further comprising at least one additional phosphor.
10. A light emitting device according to claim 8 , 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.
11. A display using the light emitting device as claimed in claim 8 as a light source.
12. A lighting system using the light emitting device as claimed in claim 8 as a light source.