Spherical crystalline silica particles having a higher productivity, lower production cost, higher coefficient of thermal expansion, higher heat transmission rate, higher fluidity, higher dispersability, higher fill factor, low abrasiveness, and higher purity compared with the past and able to be applied in the semiconductor field and a process of production of the same are provided. Spherical crystalline silica particles containing 400 to 5000 ppm of aluminum and containing 80% or more of crystal phases are provided.

To provide an apparatus and a method of producing fine particles capable of increasing evaporation efficiency of a material, increasing the production of fine particles and reducing costs by heating the inputted material by a gas heated by thermal plasma. A fine particle production apparatus includes a vacuum chamber, a material feeding device connected to the vacuum chamber and feeding material particles from a material feeding port into the vacuum chamber, electrodes arranged in the vacuum chamber for generating plasma and a collection device connected to the vacuum chamber and collecting fine particles, which produces the fine particles from the material by generating electric discharge inside the vacuum chamber, in which the collection device and the material feeding device are connected by piping, and a material heating and circulation device which heats the material by heat of a gas inside the chamber heated by the plasma through the piping is provided.

One aspect is a process for the preparation of a quartz glass body including providing a silicon dioxide granulate wherein the provision includes providing silicon dioxide powder, and processing the silicon dioxide powder to obtain a silicon dioxide granulate. The silicon dioxide granulate has a larger particle diameter than the silicon dioxide powder. The processing includes processing the silicon dioxide powder to obtain a silicon dioxide granulate I, wherein the silicon dioxide granulate I has a first carbon content wC(1), treating the silicon dioxide granulate I with a reactant to obtain a silicon dioxide granulate II with a further carbon content wC(2), wherein the further carbon content wC(2) is less than the first carbon content wC(1), making a glass melt out of the silicon dioxide granulate and making a quartz glass body out of at least part of the glass melt.

Compositions comprising nanoparticles (e.g., nanocrystals) of stishovite silica are described. Such nanoparticles may be made by (1) subjecting a mesoporous silica starting material (e.g., SBA-16 or KIT-6) to a pressure of less than about 20 GPa (e.g., about 12 GPa); (2) heating the mesoporous silica starting material while under pressure to an elevated temperature of less than about 1000 C. (e.g., a temperature of between about 300 C. and about 400 C.); and thereafter isolating the nanoparticles. The nanoparticles may be used in a work tool that is configured and adapted for cutting, drilling, abrading, polishing, machining, or grinding, among other uses.

A spherical silica powder with a low dielectric tangent, wherein after formulating the spherical silica powder in a resin and molding it into a sheet, in a dielectric tangent of the spherical silica powder calculated by using the following Formula (I) based on a dielectric tangent (tan ?c) of the sheet which is measured under the conditions a frequency is 35-40 GHz with a resonator method, B/A is 0.70 or lower, wherein A represents a dielectric tangent (tan ?f.sub.A) of the spherical silica powder before a dielectric tangent reduction treatment and B represents a dielectric tangent (tan ?f.sub.B) of the spherical silica powder after a dielectric tangent reduction treatment; and a specific surface area of said spherical silica powder after a dielectric tangent reduction treatment is 1-30 m.sup.2/g.

Provided are a silicon oxide-carbon composite and a method of manufacturing the same. More particularly, the present invention provides a method of manufacturing a silicon oxide-carbon composite including mixing silicon and silicon dioxide to be included in a reaction chamber, depressurizing a pressure of the reaction chamber to obtain a high degree of vacuum while increasing a temperature in the reaction chamber to a reaction temperature, reacting the mixture of silicon and silicon dioxide in a reducing atmosphere, and coating a surface of silicon oxide manufactured by the reaction with carbon, and a silicon oxide-carbon composite manufactured thereby.

The synthetic amorphous silica powder of the present invention is characterized in that it comprises a synthetic amorphous silica powder obtained by applying a spheroidizing treatment to a silica powder, and by subsequently cleaning and drying it so that the synthetic amorphous silica powder has an average particle diameter D.sub.50 of 10 to 2,000 m; wherein the synthetic amorphous silica powder has: a quotient of 1.00 to 1.35 obtained by dividing a BET specific surface area of the powder by a theoretical specific surface area calculated from the average particle diameter D.sub.50; a real density of 2.10 to 2.20 g/cm.sup.3; an intra-particulate porosity of 0 to 0.05; a circularity of 0.75 to 1.00; and an unmolten ratio of 0.00 to 0.25. This synthetic amorphous silica powder is less in amount of gas components adsorbed to surfaces of particles of the powder and in amount of gas components within the particles, so that a synthetic silica glass product manufactured by using the powder is remarkably decreased in amount of generation or degree of expansion of gas bubbles even upon usage of the product in a high temperature and reduced pressure environment.

A set of spherical inorganic particles having the particular property of being spontaneously individualized, both in dry state in the form of a powder and when they are dispersed in a matrix. The method for producing the particles, and the materials produced by including the particles in the matrices are also described.

Disclosed herein are a SiOx nanoparticle manufacturing apparatus that can not only manufacture a SiOx nanoparticle in large quantities but also prevent a silicon melt residue from being stuck and solidified on an inner bottom surface of a crucible by designing a sliding type tapping structure, and a SiOx nanoparticle manufacturing method using the same.

A process for producing solar grade silicon from silica sand employs a plurality of plasma furnaces to perform a sequence of chemical reactions together with other process steps to produce solar grade silicon. The plasma furnace generates a stable dirty air, donut-shaped plasma into which particulate matter can be introduced. The plasma in the first two stages is formed by gases from the chemical reactions and in the third from inert gasses. Cyclone separators are used to extract particulates from the plasma in an inert gas that prevents reverse reactions as the particular cools.