Electroluminescent phosphor powders, methods for making phosphor powders and devices incorporating same
AssigneeSuperior MicroPowders LLC
InventorsMark J. Hampden-Smith, Toivo T. Kodas, James Caruso, Daniel J. Skamser, Quint H. Powell, Klaus Kunze
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Abstract
Electroluminescent phosphor powders and a method for making phosphor powders. The phosphor powders have a small particle size, narrow particle size distribution and are substantially spherical. The method of the invention advantageously permits the economic production of such powders. The invention also relates to improved devices, such as electroluminescent display devices, incorporating the phosphor powders.
Claims92
A powder batch comprising electroluminescent phosphor particles selected from the group consisting of M2Ga2S4, wherein M2 is selected from the group consisting of Ca, Sr and combinations thereof, ZnGa2O4, M3Ga2O4, wherein M3 is selected from the group consisting of Ca and Sr, Ga2O3, Ca3Ga2O6 and Zn2(Ge,Si)O4, and wherein said particles have a weight average particles size of from about 0.1 μm to about 10 μm and have a substantially spherical morphology, wherein at least about 80 weight percent of said particles are not larger than about two times said average particle size.
A powder batch comprising electroluminescent ZnS phosphor particles, wherein said particles have a weight average particle size of from about 0.1 μm to about 10 μm, wherein said particles are substantially spherical, wherein at least about 80 weight percent of particles are not larger than about two times said average particle size and wherein said particles have a dopant concentration of from about 0.05 to about 5 weight percent.
A powder batch comprising electroluminescent M1S phosphor particles wherein M1 is selected from the group consisting of Ba, Ca, Sr and combinations thereof, and wherein said particles have a weight average particle size of from about 0.3 μm to about 10 μm and wherein at least about 80 weight percent of said particles are not larger than about two times said average particle size.
A powder batch comprising electroluminescent M2Ga2S4 phosphor particles, wherein said M2 is selected from the group consisting of Ca, Sr and combinations thereof, and wherein said particles have a weight average particle size of from about 0.1 μm to about 10 μm.
A powder batch comprising electroluminescent phosphor particles of the form M3Ga2O4, wherein M3 is selected from the group consisting of Sr, Ca and Zn wherein said particles have a weight average particle size of from about 0.1 μm to about 10 μm and wherein at least about 80 weight percent of said particles are not larger than two times said average particle size.
A flowable medium suitable for applying electroluminescent phosphor particles onto a substrate, comprising:
- a) a liquid vehicle phase;
- and
- b) a functional phase dispersed throughout said liquid vehicle phase, said functional phase comprising electroluminescent phosphor particles selected from the group consisting of M2Ga2S4, wherein M2 is selected from the group consisting of Ca, Sr and combinations thereof, ZnGa2O4, M3Ga2O4, wherein M3 is selected from the group consisting of Ca and Sr, Ga2O3, Ca3Ga2O6 and Zn2(Ge,Si)O4, wherein said phosphor particles are substantially spherical and have a weight average particle size of not greater than about 5 μm.
A paste composition suitable for applying electroluminescent phosphor particles onto a substrate, comprising:
- a) a liquid vehicle phase;
- and
- b) a functional phase dispersed throughout said vehicle phase, said functional phase comprising electroluminescent phosphor particles selected from the group consisting of M2Ga2S4, wherein M2 is selected from the group consisting of Ca, Sr and combinations thereof, ZnGa2O4, M3Ga2O4, wherein M3 is selected from the group consisting of Ca and Sr, Ga2O3, Ca3Ga2O6 and Zn2(Ge,Si)O4, and having a weight average particle size of not greater than about 5 μm and a particle size distribution wherein at least about 80 weight percent of said particles are not larger than twice said average particle size.
An electroluminescent device comprising an electrically insulative substrate, a first electrode supported on said substrate, a phosphor layer disposed over said first electrode, a second electrode disposed over said phosphor layer, and means for applying an electric field between said first and second electrodes, wherein said phosphor layer comprises an electroluminescent phosphor powder comprising electroluminescent phosphor particles, wherein said particles are substantially spherical, have a weight average particle size of not greater than about 5 μm and wherein at least about 80 weight percent of said phosphor particles are not larger than twice said average particle size.
A method for the production of a electroluminescent phosphor powder batch, comprising the steps of:
- a) forming a liquid comprising precursors to a electroluminescent phosphor compound;
- b) generating an aerosol of droplets from said liquid;
- c) pyrolyzing said droplets to remove liquid therefrom and at least partially react said precursors to form intermediate precursor particles;
- and
- d) heating said intermediate precursor particles to form a powder batch of phosphor particles.
A method for the production of a phosphor powder batch comprising phosphor particles of the form M1S, wherein M1 is selected from the group consisting of Sr, Ca, Ba and combinations thereof, comprising the steps of:
- a) forming a liquid comprising precursors to an M1S electroluminescent phosphor compound;
- b) generating an aerosol of droplets from said liquid;
- c) pyrolyzing said droplets to remove liquid therefrom and at least partially react said precursors to form intermediate precursor particles;
- and
- d) heating said intermediate precursor particles to form a powder batch of phosphor particles.
A method for the production of a ZnS phosphor powder batch, comprising the steps of:
- a) forming a liquid comprising precursors to a ZnS electroluminescent phosphor compound;
- b) generating an aerosol of droplets from said liquid;
- c) pyrolyzing said droplets at a temperature of at least about 700° C. to remove liquid therefrom and at least partially react said precursors to form intermediate precursor particles;
- and
- d) heating said intermediate precursor particles to form a powder batch of phosphor particles.
A method for the production of a thiogallate phosphor powder of the form M2Ga2S4 wherein M2 is selected from the group consisting of Ca, Sr and combinations thereof, comprising the steps of:
- a) forming an liquid comprising precursors of a metal M2 and gallium;
- b) generating an aerosol of droplets from said liquid;
- c) pyrolyzing said droplets to remove liquid therefrom and at least partially react said precursors to form a particulate intermediate precursor comprising at least a first oxide of metal M2 and gallium;
- and
- d) heating said particulate intermediate precursor form said thiogallate phosphor powder.
Dependencies are inferred from the claim text.