Green-emitting (oxy)nitride-based phosphors and light-emitting device using the same

Abstract

A green-emitting phosphor having the formula A a B b C c O d N e ,:RE, wherein A is a positively charged divalent element; B is a positively charged trivalent element; C is a positively charged tetravalent element; and RE is a rare earth activator. The parameter a ranges from about 0.5 to about 1.5; the parameter b ranges from about 0.8 to about 3.0; the parameter c ranges from about 3.5 to about 7.0; the parameter d ranges from about 0.1 to about 3.0; and the parameter e ranges from about 5.0 to about 11.0. A is at least one of Mg, Ca, Sr, Ba, and Zn; B (the letter) is at least one of B (boron), Al, Ga, and In; C (the letter) is at least one of C (carbon), Si, Ge, and Sn; O is oxygen; N is nitrogen; and RE is at least one of Eu, Ce, Pr, Tb, and Mn.

What is claimed is: 
     
         1 . A green-emitting oxynitride phosphor having the formula A a B b C c O d N e ,:RE, wherein:
 A is a positively charged divalent element;   B is a positively charged trivalent element;   C is a positively charged tetravalent element;   O is oxygen;   N is nitrogen;   RE is a rare earth activator;   the parameter a ranges from about 0.5 to about 1.5, endpoints inclusive;   the parameter b ranges from about 0.8 to about 3.0, endpoints inclusive;   the parameter c ranges from about 3.5 to about 7.0;   the parameter d ranges from about 0.1 to about 3.0; and   the parameter e ranges from about 5.0 to about 11.0, endpoints inclusive;   wherein the parameters a, b, c, d and e are chosen to provide a phosphor configured to emit light having a peak emission wavelength ranging from about 500 nm to about 550 nm under excitation of blue light ranging from about 420 nm to about 470 nm.   
     
     
         2 . The green-emitting oxynitride phosphor of  claim 1 , wherein:
 the parameter a ranges from about 0.8 to about 1.0, endpoints inclusive;   the parameter b ranges from about 1.0 to about 1.3, endpoints inclusive;   the parameter c ranges from about 4.0 to about 5.0;   the parameter d ranges from about 0.1 to about 1.0; and   the parameter e ranges from about 6.0 to about 8.0, endpoints inclusive.   
     
     
         3 . The green-emitting oxynitride phosphor of  claim 1 , wherein:
 A is at least one of Mg, Ca, Sr, Ba, and Zn, individually or in combinations;   B (the letter) is at least one of B (boron), Al, Ga, and In, individually or in combinations;   C (the letter) is at least one of C (carbon), Si, Ge, and Sn; and   RE is at least one of Eu, Ce, Pr, Tb, and Mn, individually or in combinations.   
     
     
         4 . The green-emitting oxynitride phosphor of  claim 1 , wherein:
 A is at least one of Sr and Ca;   B is Al;   C is Si; and   RE is Eu.   
     
     
         5 . The green-emitting oxynitride phosphor of  claim 4 , wherein A is Sr. 
     
     
         6 . The green-emitting oxynitride phosphor of  claim 3 , wherein the phosphor is characterized by an x-ray diffraction pattern comprising major diffraction peaks at 2θ values of about 25, 31, 32, 37, 62, 63, and 64 degrees. 
     
     
         7 . The green-emitting oxynitride phosphor of  claim 3 , wherein the phosphor is characterized by an x-ray diffraction pattern as in (1) in  FIG. 6 . 
     
     
         8 . The green-emitting oxynitride phosphor of  claim 1 , wherein the phosphor has the formula Eu 2+ :M 2+  Si 4+x Al 1+y O (2x+3y/2) N 7 , wherein:
 x ranges from greater than zero to less than or equal to 1.0, and y ranges from greater than zero to less than or equal to 0.5, wherein 2x+3y/2 is greater than or equal to 0.1; and   M 2+  represents one or more different divalent metals selected from the group consisting of Mg, Ca, Sr, Ba, and Zn.   
     
     
         9 . The green-emitting oxynitride phosphor of  claim 8 , wherein M 2+  is Sr. 
     
     
         10 . The green-emitting oxynitride phosphor of  claim 9 , wherein the phosphor is Eu:SrAlSi 4.25 O 0.5 N 7 . 
     
     
         11 . The green-emitting oxynitride phosphor of  claim 8 , wherein x is chosen to shift the peak emission intensity to a shorter wavelength by at least 100 nm from the peak emission intensity at x=0. 
     
     
         12 . The green-emitting oxynitride phosphor of  claim 1 , wherein the phosphor has the formula Eu 2+ :M 2+  Si 4 AlO x N 7−2x/3 , wherein:
 x ranges from greater than or equal to 0.1 to less than or equal to 1.0; and   M 2+  represents one or more different divalent metals selected from the group consisting of Mg, Ca, Sr, Ba, and Zn.   
     
     
         13 . The green-emitting oxynitride phosphor of  claim 12 , wherein M 2+  is Sr. 
     
     
         14 . The green-emitting oxynitride phosphor of  claim 13 , wherein the phosphor is Eu:SrAlSi 4 O 0.5 N 20/3 . 
     
     
         15 . The green-emitting oxynitride phosphor of  claim 12 , wherein x is chosen to shift the peak emission intensity to a shorter wavelength by at least 100 nm from the peak emission intensity at x=0. 
     
     
         16 . The green-emitting oxynitride phosphor of  claim 1 , wherein the phosphor has the formula Eu 2+ :M 2+  Si 4+x AlO 0.5 N 7+(4x−1)/3 , wherein:
 x ranges from zero to less than or equal to 3.0; and   M 2+  represents one or more different divalent metals selected from the group consisting of Mg, Ca, Sr, Ba, and Zn.   
     
     
         17 . The green-emitting oxynitride phosphor of  claim 16 , wherein M 2+  is Sr. 
     
     
         18 . The green-emitting oxynitride phosphor of  claim 17 , wherein the phosphor is Eu:SrAlSi 4.5 O 0.5 N 22/3 . 
     
     
         19 . The green-emitting oxynitride phosphor of  claim 1 , wherein the phosphor has the formula Eu 2+ :M 2+  Si 4.5 Al 1+y O 0.5 N y+22/3 , wherein:
 y ranges from zero to less than or equal to 2.0; and   M 2+  represents one or more different divalent metals selected from the group consisting of Mg, Ca, Sr, Ba, and Zn.   
     
     
         20 . The green-emitting oxynitride phosphor of  claim 19 , wherein M 2+  is Sr. 
     
     
         21 . The green-emitting oxynitride phosphor of  claim 20 , wherein the phosphor is Eu:SrAl 2 Si 4.5 O 0.5 N 25/3 . 
     
     
         22 . An oxynitride phosphor having the chemical formula A a B b C c O d N e :Eu and characteristic x-ray diffraction pattern comprising major diffraction peaks at 2θ values of about 25, 31, 32, 37, 62, 63, and 64 degrees, wherein:
 A is at least one of Mg, Ca, Sr, and Ba; 
 B is at least one of Al and Ga; 
 C is at least one of Si and Ge; 
 O is oxygen; and 
 N is nitrogen; 
 wherein the parameters a, b, c, d and e are chosen to provide a phosphor configured to emit light having a peak emission wavelength ranging from about 510 nm to about 540 nm under UV to blue excitation. 
 
     
     
         23 . A white light illumination system comprising:
 an excitation source with emission wavelength within a range of 200 nm to 480 nm;   a red phosphor with emission wavelength range of 600 nm to 670 nm; and   an oxynitride phosphor having the chemical formula A a B b C c O d N e :Eu and characteristic x-ray diffraction pattern comprising major diffraction peaks at 2θ values of about 25, 31, 32, 37, 62, 63, and 64 degrees, wherein:
 A is at least one of Mg, Ca, Sr, and Ba; 
 B is at least one of Al and Ga; 
 C is at least one of Si and Ge; 
 O is oxygen; and 
 N is nitrogen; 
 wherein the parameters a, b, c, d and e are chosen to provide a phosphor configured to emit light having a peak emission wavelength ranging from about 510 nm to about 540 nm. 
   
     
     
         24 . The white light illumination system of  claim 23 , wherein the red phosphor is at least one of the phosphors selected from the group (Sr,Ca)AlSiN 3 :Eu 2+  and (Sr,Ca) 2 Si 5 N 8 :Eu 2+ .