Production Of Fine Particles Of Functional Ceramic By Using Pulsed Laser

Abstract

A method of forming nanometer sized fine particles of functional ceramic from a bulk functional ceramic, particularly fine particles of phosphorous ceramics from a bulk phosphor material is disclosed. The method relies on irradiation of a bulk phosphorous ceramic in a liquid with an ultrashort-pulsed-laser-fragmentation beam to thereby form nanometer sized particles of the phosphorous ceramic. The method is unique in that the generated particles retain the chemical and crystalline properties of the bulk phosphorous ceramic. The generated solutions are stable colloids from which the particles can be isolated or used as is.

We claim: 
     
         1 . A solution of fine particles of a multi-element ceramic comprising:
 a liquid; and   fine particles of a multi-element ceramic having at least three elements and an average particle size of from 1 to 5000 nanometers in diameter dispersed in said liquid, wherein said fine particles are derived from a bulk material of said multi-element ceramic having at least three elements by ultrashort-pulsed-laser-fragmentation processing using pulses having a pulse duration of 500 picoseconds or less, and wherein said fine particles retain the chemical composition and crystalline structure of said bulk material.   
     
     
         2 . The solution of  claim 1 , wherein said ultrashort-pulsed-laser-fragmentation processing is done using pulses having a pulse duration of 10 femtoseconds to 20 picoseconds. 
     
     
         3 . The solution of  claim 1 , wherein said multi-element ceramic is a phosphor material. 
     
     
         4 . The solution of  claim 1 , wherein said fine particles are super fine particles having an average diameter of from 1 to 1000 nanometers. 
     
     
         5 . The solution of  claim 1 , wherein said fine particles comprise oxides, nitrides, nitrogen oxides, oxynitrides, garnet, spinel, silica, SiAlON, or mixtures thereof. 
     
     
         6 . The solution of  claim 1 , wherein said fine particles comprise at least one of aluminum indium gallium nitride (AlInGaN), aluminum gallium arsenide (AlGaAs),), aluminum gallium indium phosphide (AlGaInP),), indium gallium phosphide (InGaP),), indium aluminum phosphide (InAlP), or a mixture thereof. 
     
     
         7 . The solution of  claim 1 , wherein said fine particles comprise at least one of: Ca 10 (PO 4 ) 6 FCl:Sb,Mn; M 5 (PO 4 ) 3 Cl:Eu, wherein M is at least one material selected from the group of Sr, Ca, Ba and Mg; BaMg 2 Al 16 O 27 : Eu; BaMg 2 Al 16 O 27 : Eu, Mn; 3.5MgO 0.5MgF 2  GeO: Mn; Y 2 O 2   5 : Eu; Mg 6 As 2 O 11 : Mn; Sr 4 Al 14 O 25 :Eu; (Zn,Cd)S: Cu; SrA 12 O 4 : Eu; Ca 10 (PO 4 ) 6 ClBr: Mn, Eu; Zn 2 GeO 4 : Mn; Gd 2 O 2 S: Eu; La 2 O 2 S: Eu; Sr 2 SiO 4 : Eu; Y 2 Al 5 O 12 ; Ce; Y 2 Al 5 O 12 : Tb; SrGa 2 S 4 :Eu; SrS: Eu; BaMgAl 10 O 17 :Eu; BaMgAl 10 O 17 : Eu, Mn; Y 2 O 3 : Eu; SrAl 2 O 4 : Eu, Dy; LaPO 4 :Ce, Tb; or mixtures thereof. 
     
     
         8 . The solution of  claim 1 , wherein at least one element of said multi-element ceramic is a rare earth element. 
     
     
         9 . The solution of  claim 8 , wherein said fine particles further comprise silica and wherein said rare earth element is dispersed in said silica. 
     
     
         10 . The solution of  claim 1 , wherein said liquid comprises at least one of water, an alcohol, a ketone, an aldehyde, an organic acid, an aromatic group containing liquid, a volatile organic compound, or mixtures thereof. 
     
     
         11 . The solution of  claim 1 , wherein said fine particles can function as at least one of:
 a phosphor in a light emitting device comprising at least one of a light emitting diode or a light bulb; as a laser gain medium in a laser device; or as a luminescent agent in a chemical or biological or medical sensing or imaging method.   
     
     
         12 . The solution of  claim 1 , wherein the retention of said chemical composition or said crystalline structure of said bulk material in said fine particles can be characterized by at least one of luminescence spectrum under excitation by external energy or by X-ray diffraction.