Phosphors of rare earth and transition metal doped ca1+xsr1-xgayin2-yszse3-zf2; methods of manufacturing and applications

Abstract

Energy down conversion phosphors represented by the chemical formula Ca 1+x Sr 1−x Ga y In 2−y S z Se 3−z F 2 where (0≦x≦1, 0≦y≦2, 0≦z≦3) doped with rare earth and/or transition metal elements is disclosed. Dopant impurities may be one or more species such as Eu, Ce, Mn, Ru, and/or mixtures thereof present as activators. The molar fractions x, y and z, the dopant species and the dopant concentration may be varied to tune the peak emission wavelength and/or the width of the emission peak.

1 . A method for synthesizing a rare earth or transition metal doped phosphor having a general formula Ca 1+x Sr 1−x Ga y In 2−y S z Se 3−z F 2  wherein 0≦x≦1, 0≦y≦2 and 0≦z≦3, comprising the steps of:
 providing a plurality of reactants suitable for formulating the rare earth or transition metal doped phosphor having the general formula Ca 1+x Sr 1−x Ga y In 2−y S z Se 3−z F 2 , wherein the reactants are a mixture of elements selected from the group consisting of: Ca, Sr, Ga, In, S, Se, and F and/or compounds containing the elements Ca, Sr, Ga, In, S, Se, or F, and at least one rare earth or transition metal dopant; 
 mixing the reactants into a homogenous powder; 
 reacting the homogenous powder inside a high temperature furnace or in the presence of an ambient inert gas, forming a reacted alloy; 
 grinding the reacted alloy into a fine powder; 
 annealing the fine powder under vacuum or in the presence of an ambient inert gas, forming an annealed powder; and 
 washing the annealed powder with an etching solution to form a chemically treated powder. 
 
     
     
         2 . The method of  claim 1 , further comprising the steps of:
 transferring the chemically treated powder to a storage medium; and   drying the chemically treated powder under a vacuum or inert gas.   
     
     
         3 . The method of  claim 1 , further comprising the step of:
 transferring the chemically treated powder to an epoxy mixture.   
     
     
         4 . The method of  claim 1 , wherein the reactants are Ca, Ga, Sr, S, Se, Sr(OH) 2 , SrCO 3 , SrCl 2 , SrO, SrF 2 , CaO, CaF 2 , Ga 2 O 3 , GaS, GaSe, CaS, SrS, SrSe, EuCl 3 , ErO 3 , EuF 2 , CeCl 3 , Eu, Ce, Pr, Tb, Ru, Er, Mn or mixtures thereof. 
     
     
         5 . The method of  claim 1 , wherein the reacting step occurs at a temperature between 900° C. and 1050° C. 
     
     
         6 . The method of  claim 1 , wherein the grinding step is performed at room temperature. 
     
     
         7 . The method of  claim 1 , wherein the annealing step occurs at 850° C. to 900° C. 
     
     
         8 . The method of  claim 1 , wherein the ambient inert gas is at least one of argon and hydrogen. 
     
     
         9 . The method of  claim 1 , wherein the etching solution comprises water and a base selected from the group consisting of: KOH, NaOH, NH 4 OH, and mixtures thereof. 
     
     
         10 . The method of  claim 1 , wherein the etching solution has a pH in a range of about 8 to about 12. 
     
     
         11 . The method of  claim 3 , further comprising the step of coating a glass plate with the epoxy mixture and baking the coated glass plate under a nitrogen or an argon gas flow to form a solid film. 
     
     
         12 . The method of  claim 2 , wherein the storage medium is an organic solution. 
     
     
         13 . A phosphor composition comprising:
 an alloy having a general Ca 1+x Sr 1−x Ga y In 2−y S z Se 3−z F 2  wherein 0≦x≦1, 0≦y≦2, and 0≦z≦3; and   a rare earth or transition metal dopant, doped into the alloy as an impurity, wherein the phosphor composition has a wall plug efficiency greater than 100 lumens/watt.   
     
     
         14 . The composition of  claim 13 , wherein the rare earth or transition metal dopant is Eu, Ce, Pr, Tb, Ru, Er, Mn or mixtures thereof. 
     
     
         15 . The phosphor composition of  claim 13 , wherein the rare earth or transition metal dopant is EuCl 3 , Er 2 O 3 , EuF 2 , CeCl 3  or mixtures thereof. 
     
     
         16 . The phosphor composition of  claim 13 , wherein the alloy is Ca 2 Ga 2 S 3 F 2 , CaSrGa 2 SSe 2 F 2 , CaSrGaInSe 3 F 2 , CaSrGa 2 S 3 F 2 , Ca 2 Ga 2 SSe 2 F 2 , or a mixture thereof. 
     
     
         17 . The phosphor composition of  claim 13 , wherein the phosphor composition exhibits a peak emission wavelength of about 540 nm to about 600 nm. 
     
     
         18 . The phosphor composition of  claim 13 , wherein the phosphor composition exhibits a peak emission wavelength of about 530 nm. 
     
     
         19 . The phosphor composition of  claim 13 , wherein the rare earth or transition metal dopant is present in the alloy in an amount in a range of about 0.001 mol % to about 10 mol %. 
     
     
         20 . The phosphor composition of  claim 13 , wherein the wall plug efficiency is about 117-121 lumens/watt. 
     
     
         21 . A method for down converting photon energy comprising the steps of:
 providing a phosphor having a general formula Ca 1+x Sr 1−x Ga y In 2−y S z Se 3−z F 2 :D, wherein D is a dopant comprising one or more rare earth or transition metal elements;   absorbing by the phosphor, a photon of higher energy; and   emitting from the phosphor, photons each having a lower energy than the photon of higher energy.   
     
     
         22 . The method of  claim 21 , wherein the photon being absorbed by the phosphor has a UV, blue or green wavelength. 
     
     
         23 . The method of  claim 21 , wherein the photons being emitted have a green, yellow or red wavelength. 
     
     
         24 . The method of  claim 21 , wherein the dopant is Eu, Ce, Pr, Tb, Ru, Er, Mn or mixtures thereof. 
     
     
         25 . The method of  claim 21 , wherein the dopant is EuCl 3 , ErO 3 , EuF 2 , CeCl 3  or a mixture of dopants thereof.