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 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 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 - 12 . (canceled)  
   
   
       13 . 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.  
   
   
       14 . 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.  
   
   
       15 . 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.  
   
   
       16 . 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.  
   
   
       17 . A phosphor according to  claim 1 , wherein a brightness keeping percentage of said phosphor is not less than 90%.  
   
   
       18 . 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.  
   
   
       19 . A light emitting device according to  claim 18 , further comprising at least one additional phosphor.  
   
   
       20 . A light emitting device according to  claim 18 , 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.  
   
   
       21 . A display using the light emitting device as claimed in  claim 18  as a light source.  
   
   
       22 . A lighting system using the light emitting device as claimed in  claim 18  as a light source.