E.i. Dupont De Nemours and Company

Salvatore A Bruno

Ian Burn

Donald Keith Swanson

William L Monson

Horacio E Bergna

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

An ultrafine titanium dioxide powder is disclosed that can be produced by hydrothermal treating an amino titanium oxalate composition. Ultrafine titanium dioxide powders are useful in cosmetic and other applications for controlling exposure to ultraviolet (UV) light.

Hydrothermal process for making ultrafine metal oxide powders

Hydrothermal process for making ultafine metal oxide 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.

This invention resides in a process for production of predominantly a 1,4-O-metallation product of a hydride of silicon, germanium, or tin with an .alpha.,.beta.-unsaturated carbonyl compound. The reaction involved takes place in the presence of a heterogeneous noncomplexed rhodium-containing catalyst. This invention also resides in 1,4-O-metallation compositions having perfluoroalkyl R groups on either side of the C.dbd.C bond of an enol ether or on the acetal side of the C.dbd.C bond of a ketene acetal.

1,4-O-metallation process

An improved process for preparing crystalline mixed metal oxides, such as barium titanate, in which an organometallic compound is reacted simultaneously and continuously with a solution of a divalent metal ion in an alkaline high turbulence energy environment, the reaction product is crystallized, and the crystals are isolated and may be calcined.

Process for preparing crystalline mixed metal oxides

A composition consisting essentially of 60.0-70.0 mol % TiO.sub.2, 14.3-20.0 mol % Nd.sub.2 O.sub.3, 11.0-16.7 mol % BaO, 1.0-8.0 mol % ZrO.sub.2 and 0.05-0.30 mol % CeO.sub.2. This composition is useful for forming densified ceramic dielectric bodies having a dielectric constant of at least 65 and which meet COG specifications, and multilayer capacitors that contain such dielectric bodies.

Cog dielectric with high K

A composition comprising finely divided particles of modified barium titanate; and an admixture of calcium, titanium and manganese; the modified barium titanate particles containing Zr, Zn and Nb homogeneously distributed on an atomic scale throughout the particles according to the formula:

High K dielectric compositions with fine grain size

COG dielectric with high K

An improved process for preparing crystalline mixed metal oxides, such as barium titanate, in which an organometallic compound is reacted simultaneously and continuously with a solution of a divalent alkaline earth metal ion in an alkaline high turbulence energy environment, the reaction product is crystallized, and the crystals are isolated.

An improved ceramic dielectric composition comprising a chemically homogeneous distribution of a mixture of additives on the surface of particles of ceramic powder, and to a method for enhancing the dielectric properties and sinterability of such compositions at low firing temperatures.

Ceramic dielectric composition and method for preparation

An improved ceramic dielectric composition comprising a plurality of mixed metal oxide dopants distributed homogeneously on the surface of ceramic powder particles, and a method for enhancing dielectric properties of such compositions by improving the chemical homogeneity of the particles.

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Wilmington, DE, United States of America

Salvatore A Bruno