E.i. Dupont De Nemours and Company

Donald Keith Swanson

Salvatore A Bruno

Ying Wang

Walter Vladimir Cicha

Kyoichi Sasaki

Titanium oxide particles are prepared from the reaction of an aqueous basic solution with ( ) an aqueous acidic titanium salt solution, or ( ) an aqueous salt solution of a titanium salt and an aqueous salt solution of a dopant metal salt. In preferred embodiments, the particles may range in size from to microns ( meters), and possess relatively high bulk density combined with high surface area.

Process for making and using titanium oxide particles

Internal porosity is created in dense SiO.sub.2 particles by heating a mixture of the particles with B.sub.2 O.sub.3 at a temperature above about 450.degree. C. Resulting SiO.sub.2 particles have altered morphology, internal porosity, and small to negative volume changes when heated.

Low density silica particles and method for their preparation

A process suitable for producing high purity alkaline earth fluoride product is disclosed which involves (a) mixing (i) MgO, CaO, BaO, Mg(OH).sub.2, Ca(OH).sub.2, and/or Ba(OH).sub.2, (ii) NaOH, KOH and/or NH.sub.4 OH, and (iii) water, to form an aqueous slurry having a temperature of at least 20.degree. C. and an aqueous phase pH of at least 13; (b) adding fluosilicic acid, optionally adding additional water and optionally adding additional NaOH, KOH and/or NH.sub.4 OH to the slurry of (a) at a rate which maintains an aqueous phase pH of 11 or above, and in an amount to provide a molar ratio of Si: (Mg, Ca, and Ba) of at least 1:3.3, a molar ratio of (Na, K, and NH.sub.4):Si of at least 2:1, and a molar ratio of water:Si of at least 20:1, and to obtain a precipitate comprising an alkaline earth fluoride (MgF.sub.2, CaF.sub.2 and/or BaF.sub.2), and an aqueous solution of a soluble silicon anionic compound; and (c) recovering the alkaline earth fluoride product.

Alkaline earth fluoride manufacturing process

Internal porosity is created in dense SiO.sub.2 particles by heating a mixture of the particles with B.sub.2 O.sub.3 above the melting point of both mixture components. Resulting SiO.sub.2 particles have altered morphology, internal porosity, and a negative thermal expansion coefficient when heated.

Antimony doped tin oxide powder having an open pore structure wherein the pore volume is at least 0.005 cc/g for any mean pore diameter within the range of 0.1 to 8 micrometers is disclosed.

Antimony doped tin oxide electroconductive powder

Solution precipitation processes for preparing antimony doped tin oxide having improved volumetric efficiency and improved wash efficiency involving use of concentrated base and metal salt solutions are disclosed.

Processes to prepare antimony doped tin oxide electroconductive powders

The present invention relates to a novel cost efficient luminescent composition comprising particles of a core material which have been coated with a luminescent material that is distributed in the form of a chemically homogeneous layer. The average diameter of the core particle is in the range of from about 0.5 to 20 microns, and the coating corresponds to between about 2 and 30 wt % of the total composition. One aspect the invention relates to a process for preparing the composition which comprises decomposing chelated metal luminescent precursors in solution at a relatively high pH while in the presence of dispersed core particles, thereby coating the core particles with hydrous metal oxides, recovering the coated particles, washing the coated particles substantially free from soluble species, drying and calcining. In another aspect, a hydrous oxide coating is converted to a sulfide coating by treating the hydrous coating with a source of active sulfur. In yet another aspect, the invention relates to adding an acidic solution of metal oxides along with a solution of oxalic acid to a slurry of dispersed core particles which become coated with the metal oxalates, recovering the product, washing the coated particles substantially free from soluble species, drying the oxalate composition. In a further aspect of the invention, the core material and metal oxalate powders can be dry mixed and calcined at a temperature high enough to cause the oxalate to form a phosphor coating over the surface of the core particles.

Luminescent materials prepared by coating luminescent compositions onto

The present invention relates to a novel cost efficient luminescent composition comprising particles of a core material which have been coated with a luminescent material that is distributed in the form of a chemically homogeneous layer. The average diameter of the core particle is in the range of from about 0.5 to 20 microns, and the coating corresponds to between about 2 and 30 wt % of the total composition. The composition can be employed to form a luminescent film or layer within a plasma display panel.

The present invention relates to a novel cost efficient luminescent composition comprising particles of a core material which have been coated with a luminescent material that is distributed in the form of a chemically homogeneous layer. The average diameter of the core particle is in the range of from about 0.5 to 20 microns, and the coating corresponds to between about 2 and 30 wt % of the total composition. One aspect the invention relates to a process for preparing the composition which comprises decomposing chelated metal luminescent compositions in solution at a relatively high pH while in the presence of dispersed core particles, thereby coating the core particles with hydrous metal oxides, recovering the coated particles, optionally washing the coated particles substantially free from soluble species, drying and calcining. In another aspect, a hydrous oxide coating is converted to a sulfide coating by treating the hydrous coating with a source of active sulfur. In yet another aspect, the invention relates to adding an acidic solution of metal oxides along with a solution of oxalic acid to a slurry of dispersed core particles which become coated with the metal oxalates, recovering the product, washing the coated particles substantially free from soluble species, drying the oxalate composition. In a further aspect of the invention, the core material and metal oxalate powders can be dry mixed and calcined at a temperature high enough to induce at least a portion of the oxalate to form a phosphor coating over the surface of the core particles.

A dielectric ceramic powder composition for forming multilayer ceramic devices having thin dielectric layers with low porosity and having a dissipation factor which meets or exceeds X7R specifications, and consisting essentially of an admixture of a major component ceramic powder particle and minor component additives the amounts of which are controlled within certain predetermined ratios.

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Wilmington, DE, United States of America

Donald Keith Swanson