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

Abstract

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 a divalent metal element comprising at least Ca,   M 2  is a trivalent metal element comprising Sc and Lu,   M 3  is a tetravalent metal element comprising 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  comprises Si in an amount of not less than 50 mol %. 
     
     
         3 . A phosphor according to  claim 1 , wherein the divalent metal element M 1  comprises at least Ca and Mg. 
     
     
         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, Ge, 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 at least one element selected from the group consisting of Ti, Zr, Sn and Hf. 
     
     
         6 . A phosphor according to  claim 1 , wherein the tetravalent metal element M 3  other than Si in the formula (I) is Ge or Sn. 
     
     
         7 . 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. 
     
     
         8 . 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. 
     
     
         9 . 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. 
     
     
         10 . A light emitting device according to  claim 9 , further comprising at least one additional phosphor. 
     
     
         11 . A light emitting device according to  claim 9 , 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. 
     
     
         12 . A display using the light emitting device as claimed in  claim 9  as a light source. 
     
     
         13 . A lighting system using the light emitting device as claimed in  claim 9  as a light source.