Fluorescent material, fluorescent device using the same, and image display device and lighting equipment

Abstract

To present a green- to yellow-emitting phosphor whereby a light-emitting device having high color rendering properties and high luminance can be obtained, a light-emitting device employing such a phosphor, and an image display device and a lighting system, containing such a light-emitting device. A phosphor made of a compound represented by the following formula (I), which comprises, as matrix, a compound of a garnet structure and which contains, as a luminescent center ion, a metal element in the matrix: M 1 a M 2 b X c M 3 d M 4 3 O e   (I) wherein M 1 is Mg and/or Zn, M 2 is a bivalent metal element excluding Mg and Zn, X is a metal element as a luminescent center ion composed mainly of Ce, M 3 is a trivalent metal element excluding X, M 4 is a tetravalent metal element, and a, b, c, d and e are numbers satisfying the following formulae, respectively: 0.001≦a≦0.5 2.5≦b≦3.3 0.005≦c≦0.5 1.5≦d≦2.3 e ={( a+b )×2+( c+d )×3+12}/2.

1 . A phosphor made of a compound represented by the following formula (I), which comprises, as a matrix, a compound of a garnet structure and which contains, as a luminescent center ion, a metal element in the matrix:
   M 1   a M 2   b X c M 3   d M 4   3 O e   (I)   
     wherein M 1  is Mg and/or Zn, M 2  is a bivalent metal element excluding Mg and Zn, X is a metal element as a luminescent center ion composed mainly of Ce, M 3  is a trivalent metal element excluding X, M 4  is a tetravalent metal element, and a, b, c, d and e are numbers satisfying the following formulae, respectively:
   0.001≦a≦0.5 
     2 . 5 ≦b≦3.3 
   0.005≦c≦0.5 
     1 . 5 ≦d≦2.3 
     e ={( a+b )×2+( c+d )×3+12}/2. 
 
   
   
       2 . The phosphor according to  claim 1 , wherein in the formula (I), 1.5≦d≦2.2. 
   
   
       3 . The phosphor according to  claim 1 , wherein in the formula (I), 0.001≦a≦0.3. 
   
   
       4 . The phosphor according to  claim 1 , wherein in the formula (I), 0.02≦c≦0.1. 
   
   
       5 . The phosphor according to  claim 1 , wherein in the formula (I), M 2  is at least one bivalent metal element selected from the group consisting of Ca, Sr and Ba. 
   
   
       6 . The phosphor according to  claim 1 , wherein in the formula (I), M 3  is at least one trivalent metal element selected from the group consisting of Al, Sc, Ga, Y, In, La, Gd and Lu. 
   
   
       7 . The phosphor according to  claim 1 , wherein in the formula (I), M 4  is at least one tetravalent metal element selected from the group consisting of Si, Ti, Ge, Zr, Sn and Hf. 
   
   
       8 . The phosphor according to  claim 1 , wherein in the formula (I), metal element X as a luminescent center ion other than Ce is at least one metal element selected from the group consisting of Mn, Fe, Pr, Nd, Sm, Eu, Gb, Tb and Tm. 
   
   
       9 . The phosphor according to  claim 1 , wherein in the formula (I), M 1  is Mg. 
   
   
       10 . The phosphor according to  claim 1 , wherein in the formula (I), X is Ce. 
   
   
       11 . The phosphor according to  claim 1 , wherein in the formula (I), X is Ce, M 1  is Mg, M 2  is Ca, M 3  is Sc, and M 4  is Si. 
   
   
       12 . The phosphor according to  claim 1 , wherein in the formula (I), 0.01≦a≦0.5, and 0.05≦c≦0.5. 
   
   
       13 - 23 . (canceled) 
   
   
       24 . The phosphor according to  claim 1 , wherein the median diameter of the phosphor is from 5 μm to 30 μm. 
   
   
       25 . A light-emitting device comprising a light source to emit light within a range of from ultraviolet light to visible light and at least one phosphor to converting the wavelength of at least a part of the light from the light source thereby to emit light with a wavelength longer than the light from the light source, wherein the phosphor contains a phosphor as defined in  claim 1 . 
   
   
       26 . The light-emitting device according to  claim 25 , which emits white light. 
   
   
       27 . An image display device comprising a light-emitting device as defined in  claim 25 . 
   
   
       28 . A lighting system comprising a light-emitting device as defined in  claim 25 .