Osram Sylvania Inc.

Raj P Singh

Michael J Miller

David L Houck

Thomas A Wolfe

Robert G Mendenhall

Nelson E Kopatz

Diane Seymour

Michael R Pierce

Scott A Braymiller

A novel molybdenum compound, ammonium dodecamolybdomolybdate (AMM), is described which may be used in the manufacture of molybdenum metal and molybdenum carbide powders. The molybdenum compound is a dodecaheteropoly acid salt having a Keggin-type structure wherein molybdenum resides in both the hetero as well as peripheral atomic positions. The novel compound has the general formula (NH)MoMoO&#xb7;6HO. Because of its low solubility, the compound can be crystallized efficiently and at a high purity from ammonium molybdate solutions.

Ammonium dodecamolybdomolybdate and method of making

A novel molybdenum compound, ammonium dodecamolybdomolybdate (AMM), is described which may be used in the manufacture of molybdenum metal and molybdenum carbide powders. The molybdenum compound is a dodecaheteropoly acid salt having a Keggin-type structure wherein molybdenum resides in both the hetero as well as peripheral atomic positions. The novel compound has the general formula (NH ) Mo MoO .6H O. Because of its low solubility, the compound can be crystallized efficiently and at a high purity from ammonium molybdate solutions.

A method for spheridizing silicon metal particles is described. The method involves injecting irregular silicon metal particles into a high-temperature plasma reactor to melt at least 50 weight percent of the particles. The molten droplets are solidified to form substantially spherical silicon particles having a thin SiO coating which may be removed by treating with a weak hydroxide solution.

Method of spheridizing silicon metal powders

A high-surface-area heterogenite (HCoO ) material is described for use in making submicron cobalt metal powders. The HCoO material has a surface area of at least about 90 M /g and is preferably produced by dehydrating a cobalt hydroxide precipitate at 110&deg; C.

Heterogenite material for making submicron cobalt powders

A phosphor paste composition for plasma display panels (PDP) is provided which comprises a phosphor dispersed in an organic paste comprising a solvent, a binder, at least one dispersant comprising stearic acid, and a plasticizer. The paste compositions are very stable and have desirable screen-printing properties. In addition, the phosphor contained in the paste retains a high percentage of its initial brightness following binder burn-out.

Phosphor paste compositions

A high-surface-area heterogenite (HCoO ) material is described for use in making submicron cobalt metal powders. The HCoO material has a surface area of at least about 90 m /g and is preferably produced by dehydrating a cobalt hydroxide precipitate at 110&deg; C.

Heterogenite material for making submicron cobalt metal powders

A direct dissolution method for the purification of technical grade hydrated ammonium tantalum oxide (HATO), (NH ) H Ta O .nH O), and related compounds such as tantalum hydroxide and tantalum oxide is described. The method preferably uses ammonium bifluoride as fluoride source in place of the hydrofluoric acid used in the conventional methods. Other fluoride compounds such as NaF, KF, and CaF may be used.

Method for purifying a tantalum compound using a fluoride compound and sulfuric acid

A method for purifying a phosphorus containing scheelite ore is described wherein the calcite phase is selectively dissolved prior to dissolution of the apatite phase. Selective dissolution of the calcite produces several benefits: (1) a usable calcium solution, (2) enhanced apatite dissolution, and (3) lower volumes of toxic acid solution for disposal.

Purification of phosphorus containing scheelite ore

Highly pure tantalum compounds are made by slurrying hydrated ammonium tantalum oxide or tantalum hydroxide with concentrated sulfuric acid followed by dissolution with concentrated hydrofluoric acid. After diluting the concentrated acidic solution with water, a soluble potassium compound is added to precipitate a highly pure potassium fluorotantalate. Further steps are used to convert the highly pure potassium fluorotantalate into a highly pure tantalum oxide.

Method for making a highly pure tantalum compound

A method is disclosed for the dissolution and purification of tantalum pentoxide. The impure tantalum pentoxide is reacted with a potassium-containing compound to form potassium tantalate. The potassium tantalate is optionally slurried with sulfuric acid and dissolved in an HF medium. The solution is suitable for purification by conventional ion exchange or solvent extraction methods. A potassium fluorotantalate precipitate may also be formed by adding KCl to the solution. The fluorotantalate precipitate may be further processed into a pure tantalum pentoxide by suspending the precipitate in an aqueous solution optionally containing a chelating agent and adding ammonium hydroxide to form ammonium tantalum oxide which can then be converted to tantalum pentoxide by calcining at high temperature.

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Sayre, PA, United States of America

Raj P Singh