A fused quartz crucible for pulling a single crystal of silicon by the Czochralski technique, has an inner side with an inner layer of fused quartz that forms a surface, the inner layer being provided with a crystallization promoter which on heating of the fused quartz crucible during use, in crystal pulling, causes crystallization of fused quartz to form b-cristobalite, wherein the concentration C of synthetically obtained SiO.sub.2 at a distance d from the surface is greater than the concentration of synthetically obtained SiO.sub.2 at a distance d2 from the surface, where d2 is greater than d. Multiple crystals can be grown while maintaining high crystal quality.

The present application discloses a method for preparing porous glass for an electronic cigarette, comprising the following steps: heating quartz glass to a molten state for granulation; mixing boron-silicon powder and quartz glass granules, and heating a mixture to a temperature between 600° C. to 900° C. to cover peripheries of the quartz glass granules with the boron-silicon powder; and sintering the quartz glass granules covered with boron-silicon in a preset mold to obtain the porous glass for the electronic cigarette. The technical solution according to the present application can greatly improve the smoking taste of the electronic cigarette.

A method for producing rare earth metal-doped quartz glass includes the steps of (a) providing a blank of the rare earth metal-doped quartz glass, and (b) homogenizing the blank by softening the blank zone by zone in a heating zone and by twisting the softened zone along a rotation axis. Some rare earth metals, however, show a discoloration of the quartz glass, which hints at an unforeseeable and undesired change in the chemical composition or possibly at an inhomogeneous distribution of the dopants. To avoid this drawback and to provide a modified method which ensures the production of rare earth metal-doped quartz glass with reproducible properties, during homogenization according to method step (b), the blank is softened under the action of an oxidizingly acting or a neutral plasma.

A method of forming an optical element is provided. The method includes producing silica-based soot particles using chemical vapor deposition, the silica-based soot particles having an average particle size of between about 0.05 μm and about 0.25 μm. The method also includes forming a soot compact from the silica-based soot particles and doping the soot compact with a halogen in a closed system by contacting the silica-based soot compact with a halogencontaining gas in the closed system at a temperature of less than about 1200° C.

A method for producing a pore-containing opaque quartz glass includes: (a) producing porous SiO.sub.2 granulate particles from synthetically produced SiO.sub.2, (b) thermally densifying the SiO.sub.2 granulate particles to form partly densified SiO.sub.2 granulate particles, (c) forming a dispersion from the partly densified SiO.sub.2 granulate particles, (d) comminuting the partly densified SiO.sub.2 granulate particles to form a slip containing comminuted SiO.sub.2 granulate particles, (e) shaping the slip into a shaped body and forming a porous SiO.sub.2 green body with a green density rG, and (f) sintering the SiO.sub.2 green body into opaque quartz glass. To produce opaque quartz glass that is also suited for the use of spray granulate, during step (b), partly densified SiO.sub.2 granulate particles are produced with a specific surface BET-(A) between 0.025 and 2.5 m.sup.2/g, and during step (d), comminuted SiO.sub.2 granulate particles are produced with a specific surface BET-(B) between 4 and 10 m.sup.2/g.

A method of forming an opaque quartz glass component is provided. The method includes (a) providing a starting preform made of quartz glass; (b) heating at least a portion of the starting preform to a predetermined temperature at which the quartz glass of the starting preform has a viscosity in a range of 10E2 to 10E12 poise; and (c) deforming at least a portion of the heated preform at the predetermined temperature to change a shape and/or dimension(s) of the heated perform in order to form the opaque quartz glass component. The starting preform and the heated preform have respective densities of at least 2.15 g/cm.sup.3 and at least 2.10 g/cm.sup.3. The starting perform and the opaque quartz glass component have respective direct spectral transmissions of approximately 0.1-1% and 0.2-3% in the wavelength range of λ=190 nm to λ=4990 nm at a wall thickness of 3 mm and a diffuse reflectance of at least 60% in a wavelength range of λ=190 nm to λ=2500 nm.

A method for producing a blank from titanium-doped, highly silicic-acidic glass having a specified fluorine content for use in EUV lithography is described, in which the thermal expansion coefficient over the operating temperature remains at zero as stably as possible. The course of the thermal expansion coefficient of Ti-doped silica glass depends on a plurality of influencing factors. In addition to the absolute titanium content, the distribution of the titanium is of significant importance, as is the ratio and distribution of additional doping elements, such as fluorine. In the method, fluorine-doped TiO.sub.2—SiO.sub.2 soot particles are generated and processed further via consolidation and vitrifying into the blank, and, by flame hydrolysis of input substances containing silicon and titanium, TiO.sub.2—SiO.sub.2-soot particles are formed, exposed to a reagent containing fluorine in a moving powder bed, and converted to the fluorine-doped TiO.sub.2—SiO.sub.2-soot particles.

One aspect relates to a process for the preparation of a quartz glass body. The process includes providing a silicon dioxide granulate from a pyrogenically produced silicon dioxide powder, making a glass melt out of silicon dioxide granulate, and making a quartz glass body out of at least part of the glass melt. The size of the quartz glass body is reduced to obtain a quartz glass grain. The quartz glass body is processed to make a preform and an opaque quartz glass body is made from the preform. One aspect further relates to an opaque quartz glass body which is obtainable by this process. One aspect further relates to a reactor and an arrangement, which are each obtainable by further processing of the opaque quartz glass body.

One aspect relates to a process for the preparation of a quartz glass body. The process includes providing a silicon dioxide granulate I prepared from a pyrogenically produced silicon dioxide powder, treating the silicon dioxide granulate I with a reactant at a temperature in a range from 1000 to 1300° C., and making a glass melt out of the silicon dioxide granulate. A quartz glass body is made out of at least a part of the glass melt. Furthermore, one aspect relates to a quartz glass body obtainable by this process. Furthermore, one aspect relates to a light guide, an illuminant, and a formed body, each of which is obtainable by further processing of the quartz glass body. One aspect additionally relates to a process for the preparation of a silicon dioxide granulate II.

Doped quartz glass components for use in a plasma-assisted manufacturing process contain at least one dopant which is capable of reacting with fluorine to form a fluoride compound, and the fluoride compound has a boiling point higher than that of SiF.sub.4. The doped quartz glass component has high dry-etch resistance and low particle formation, and has uniform etch removal when used in a plasma-assisted manufacturing process. The doped quartz glass has a microhomogeneity defined by (a) a surface roughness with an R.sub.a value of less than 20 nm after the surface has been subjected to a dry-etching procedure as specified in the description, or (b) a dopant distribution with a lateral concentration profile in which maxima of the dopant concentration are at an average distance apart of less than 30 μm.