Sulfur-containing 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
Life of this patent
Estimating the term…
Abstract
Sulfur-containing phosphor powders, methods for making phosphor powders and devices incorporating same. The powders have a small particle size, narrow particle size distribution and are substantially spherical. The method of the invention permits the continuous production of such powders. The invention also relates to products such as display devices incorporating such phosphor powders.
Claims102
A powder batch comprising thiogallate phosphor particles comprising a thiogallate host material, wherein said phosphor particles have a weight average particle size of not greater than about 5 .mu.m and wherein said powder batch comprises no greater than about 1 atomic percent impurities.
A method for the production of sulfur-containing phosphor particles, comprising the steps of:
- a) generating an aerosol of droplets from a liquid wherein said liquid comprises a sulfur-containing phosphor precursor and wherein said droplets have a size distribution such that at least about 80 weight percent of said droplets have a size of from about 1 .mu.m to about 5 .mu.m and no greater than about 20 weight percent of said droplets in said aerosol are larger than about twice the weight average droplet size;
- b) moving said droplets in a carrier gas;
- and
- c) heating said droplets to remove liquid therefrom and form sulfur-containing phosphor particles.
A method for the production of coated sulfur-containing phosphor particles, comprising the steps of:
- a) forming a liquid solution comprising a sulfur-containing phosphor precursor;
- b) generating an aerosol of droplets from said liquid solution;
- c) moving said droplets in a carrier gas;
- d) heating said droplets to remove liquid therefrom and form particles comprising a sulfur-containing phosphor;
- and
- e) coating an outer surface of said sulfur-containing phosphor particles.
A method for the production of a thiogallate phosphor powder of the form M.sup.1 (M.sup.2,Ga).sub.2 S.sub.4 wherein M.sup.1 is selected from the group consisting of Ca, Sr, Ba, Mg and mixtures thereof and M.sup.2 is selected from the group consisting of Al and In, comprising the steps of:
- a) forming an aqueous-based solution comprising precursors of metals M.sup.1,M.sup.2 and gallium;
- b) generating an aerosol of droplets from said aqueous-based solution;
- c) heating said droplets to form a particulate intermediate compound that is capable of being post-treated to form said thiogallate phosphor;
- and
- d) treating said particulate intermediate compound to form said thiogallate phosphor powder wherein said thiogallate phosphor powder comprises not greater than about 1 atomic percent impurities.
A method for the production of coated sulfur-containing phosphor particles, comprising the steps of:
- a) forming a liquid solution comprising a sulfur-containing phosphor precursor and a coating precursor;
- b) generating an aerosol of droplets from said liquid solution;
- c) moving said droplets in a carrier gas;
- and
- d) heating said droplets to remove liquid therefrom and form coated sulfur-containing phosphor particles.
A flat panel display, comprising:
- a) an excitation source adapted to stimulate a phosphor;
- and
- b) a viewing panel proximate to said excitation source, comprising a transparent substrate having disposed thereon a sulfur-containing phosphor powder defining pixels, wherein said phosphor powder comprises substantially spherical particles having a weight average particle size of not greater than about 10 .mu.m, wherein said flat panel display is a plasma display.
A field emission display, comprising:
- a) a back plate portion comprising a plurality of electron tip emitters;
- b) a transparent front plate portion comprising a layer of phosphor powder comprising coated sulfur-containing phosphor particles, wherein said phosphor particles have a weight average particle size of not greater than about 5 .mu.m and a particle size distribution wherein at least about 90 weight percent of said particles are not larger than twice said average particle size and wherein said phosphor particles comprise a coating having an average thickness of not greater than about 10 nanometers substantially encapsulating said particles.
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 phosphor powder comprising mixed metal sulfide phosphor particles of the general formula (M.sup.1,M.sup.2)S wherein M.sup.1 and M.sup.2 are selected from the Group 2 metals, wherein said phosphor particles are substantially spherical and have a weight average particle size of not greater than about 5 .mu.m.
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 a phosphor powder comprising mixed-metal sulfide phosphor particles having an average particle size of not greater than about 5 .mu.m and wherein said particles comprise crystallites having an average crystallite size of at least about 25 nanometers.
A method for securing a document, comprising the step of applying a phosphor powder to said document, wherein said phosphor powder comprises phosphor particles comprising an oxysulfide host material and at least two activator ions, wherein said phosphor particles have a weight average particle size of not greater than about 5 .mu.m.
A flowable medium suitable for applying 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 thiogallate phosphor particles, wherein said thiogallate phosphor particles are substantially spherical, have a weight average particle size of not greater than about 5 .mu.m and an average crystallite size of at least about 25 nanometers and wherein said flowable medium comprises from about 5 to about 95 weight percent of said thiogallate phosphor particles.
Dependencies are inferred from the claim text.