Abstract: The present invention is directed to a single-crystal silicon pulling silica container, the silica container including a straight body portion, a curved portion, and a bottom portion, wherein the OH group concentration in the straight body portion is 30 to 300 ppm by mass, the OH group concentration in the bottom portion is 30 ppm by mass or less, and the difference in the OH group concentration between the straight body portion and the bottom portion is 30 ppm by mass or more. As a result, a low-cost single-crystal silicon pulling silica container, the silica container that can reduce cavity defects called voids and pinholes in pulled single crystal silicon, is provided.

Abstract: A method for producing a silica container having a rotational symmetry is provided. The method includes forming a preliminarily molded article by feeding a powdered substrate's raw material to an inner wall of an outer frame having aspiration holes with rotating the frame, and forming a silica substrate. The preliminarily molded article is aspirated from an outer peripheral side with controlling a humidity inside the outer frame by ventilating gases present in the outer frame with charging from inside the preliminarily molded article a gas mixture comprised of an O2 gas and an inert gas and made below a prescribed dew-point temperature by dehumidification, and at the same time heated from inside the preliminarily molded article by a discharge-heat melting method with carbon electrodes, thereby making an outer peripheral part of the preliminarily molded article to a sintered body while an inner peripheral part to a fused glass body.

Abstract: A single-crystal silicon pulling silica container includes: a transparent layer made of transparent silica glass in an inner side of the silica container, and an opaque layer made of opaque silica glass containing gaseous bubbles in an outer side of the silica container, wherein the transparent layer is constituted of a high-OH group layer that is placed in an inner surface side of the silica container and contains the OH group at a concentration of 200 to 2000 ppm by mass and a low-OH group layer that has the OH group concentration lower than that of the high-OH group layer, and Ba is applied to the inner surface of the high-OH group layer at a concentration of 25 to 1000 ?g/cm2.

Abstract: A method for producing a silica container, the method including forming a preliminarily molded silica substrate to an intended shape by feeding a powdered substrate's raw material (silica particles) to an inner wall of a carbon-made outer frame having aspiration holes with rotating the outer frame, and forming the silica substrate wherein the preliminarily molded substrate is degassed by aspiration from its outer peripheral side with charging from an inner peripheral side of the preliminarily molded silica substrate a reducing gas containing more than 10% by volume of an H2 gas, and at the same time heated from inside the preliminarily molded silica substrate by a discharge-heat melting method with carbon electrodes, thereby making an outer peripheral part of the preliminarily molded silica substrate to a sintered body while an inner peripheral part of the preliminarily molded silica substrate to a fused glass body.

Abstract: The present invention provides a single-crystal silicon pulling silica container including an outer layer made of opaque silica glass containing gaseous bubbles and an inner layer made of transparent silica glass that does not substantially contain the gaseous bubbles; the container also including: a bottom portion, a curved portion, and a straight body portion, wherein continuous grooves are formed on a surface of the inner layer from at least part of the bottom portion to at least part of the straight body portion through the curved portion. As a result, there are provided the single-crystal silicon pulling silica container that can reduce defects called voids or pinholes in the pulled single-crystal silicon and a method for manufacturing such a silica container.

Abstract: [Problem] The provision of a synthetic quartz glass heat treatment method that can, by a single heat treatment, and without particular limitations on the OH group concentration distribution of the starting material, regulate the birefringence fast axis direction in the synthetic quartz glass after it has been heat-treated. [Means of Overcoming the Problem] A heat treatment method for synthetic quartz glass whereby columnar synthetic quartz glass having two opposing end faces and a lateral face is heat-treated covered with thermal insulator; wherein said heat treatment is performed using as end face thermal insulator which covers said two end faces, and as lateral face thermal insulator which covers said lateral face, thermal insulators that differ in at least either type or thickness to afford different thermal insulation effects such that the birefringence fast axis direction of said synthetic quartz glass is regulated.

Abstract: The present invention is directed to a silica container for pulling single crystal silicon, the silica container including a straight body portion, a curved portion, and a bottom portion, wherein the outside of the silica container is made of opaque silica glass containing gaseous bubbles, the inside of the silica container is made of transparent silica glass containing substantially no gaseous bubble, and, on the inner surface of the bottom portion, a silica glass layer containing the OH group in a concentration of more than 300 ppm by mass but 3000 ppm by mass or less, the silica glass layer having a thickness of 20 ?m or more but 1000 ?m or less, is formed. As a result, a low-cost silica container for pulling single crystal silicon, the silica container that can reduce cavity defects called voids and pinholes in pulled single crystal silicon, is provided.

Abstract: It is an object of the present invention to provide a copper-containing silica glass which emits fluorescence having a peak in a wavelength range of from 520 nm to 580 nm under irradiation of ultraviolet light with a wavelength of 400 nm or less, and which is excellent in long term stability even in the high output use. The copper-containing silica glass is made to have copper of from 5 wtppm to 200 wtppm, which emits fluorescence having a peak in a wavelength range of from 520 nm to 580 nm under irradiation of ultraviolet light with a wavelength ranging from 160 nm to 400 nm, and in which an internal transmittance per 2.5 mm thickness at a wavelength of 530 nm is 95% or more.

Abstract: A quartz glass crucible for silicon single crystal pulling operation that by a simple arrangement, attains prevention of any collapse onto the inside at a superior edge of straight trunk part; and a process for manufacturing the same. The quartz glass crucible for silicon single crystal pulling operation having a straight trunk part and a bottom part, is characterized in that at least the straight trunk part is provided with a gradient of fictive temperature so that the fictive temperature on the outermost side thereof is 25° C. or more lower than the fictive temperature on the innermost side thereof.

Abstract: A silica container contains a substrate having a rotational symmetry, containing mainly a silica, and gaseous bubbles in a peripheral part of the substrate; a transparent silica glass in an inner peripheral part of the substrate; and an inner layer, formed on an inner surface of the substrate and containing a transparent silica glass; wherein the substrate contains Li, Na, and K in a total concentration of 50 or less ppm by weight; the substrate has a linear light transmittance of 91.8% to 93.2% at a light wavelength of 600 nm; the inner layer contains Li, Na, and K in a total concentration of 100 or less ppb by weight and at least one of Ca, Sr, and Ba in a total concentration of 50 to 2000 ppm by weight; and the inner layer has a linear light transmittance of 91.8% to 93.2% at a light wavelength of 600 nm.

Abstract: A method for producing a silica container includes forming a preliminarily molded substrate, wherein a first powdered raw material is fed to an inner wall of an outer frame having aspiration holes while rotating the outer frame; forming a preliminarily molded intermediate layer, wherein a second powdered raw material added with an aluminum compound or a crystal nucleating agent as an additive is fed to an inner wall of the preliminarily molded substrate; and forming an inner layer, wherein the preliminarily molded substrate and the preliminarily molded intermediate layer are degassed by aspiration from a peripheral side with heating from an inside forming a substrate and an intermediate layer, and a third powdered raw material having a high silica purity is spread from inside the substrate having the formed intermediate layer with heating from the inside forming an inner layer on an inner surface of the intermediate layer.

Abstract: Producing a silica container includes forming a powder mixture by adding an Al compound or a crystal nucleating agent into a first powdered raw material; preliminarily molding to an intended shape by feeding the powder mixture to an inner wall of an outer frame while rotating the outer frame having aspiration holes; forming a silica substrate; and forming a transparent silica glass layer on an inner surface of the silica substrate, wherein the preliminarily molded article is degassed by aspiration from a peripheral side and heated from inside the preliminarily molded article at high temperature making a peripheral part of the preliminarily molded article to a sintered body while an inner part to a fused glass body, and a second powdered raw material having a higher silica purity than the first powdered raw material is spread from inside the silica substrate and heated from the inside at high temperature.

Abstract: A method for producing a silica container comprising: forming a preliminarily molded substrate, wherein a first powdered raw material is fed to an inner wall of an outer frame having aspiration holes while rotating the outer frame; forming a preliminarily molded intermediate layer, wherein a second powdered raw material added with an aluminum compound or a crystal nucleating agent as an additive is fed to an inner wall of the preliminarily molded substrate; and forming an inner layer, wherein the preliminarily molded substrate and the preliminarily molded intermediate layer are degassed by aspiration from a peripheral side with heating from an inside thereby forming a substrate and an intermediate layer, and while a third powdered raw material having a high silica purity is spread from inside the substrate having the formed intermediate layer with heating from the inside thereby forming an inner layer on an inner surface of the intermediate layer.

Abstract: A method for producing a silica container that includes forming a powder mixture by adding an Al compound or a crystal nucleating agent into a first powdered raw material (silica particles), preliminarily molding to an intended shape by feeding the powder mixture to an inner wall of an outer frame while rotating the outer frame having aspiration holes, forming a silica substrate, wherein the preliminarily molded article is degassed by aspiration from a peripheral side and at the same time heated from inside the preliminarily molded article at high temperature thereby making a peripheral part of the preliminarily molded article to a sintered body while an inner part to a fused glass body, and forming a transparent silica glass layer on an inner surface of the silica substrate, wherein a second powdered raw material having a higher silica purity than the first powdered raw material is spread from inside the silica substrate and at the same time heated from the inside at high temperature.

Abstract: Disclosed is a printed wiring board which attains aims of printed wiring boards required for realizing high-speed, high-frequency semiconductor devices, namely a printed wiring board having low dielectric constant, low dielectric loss tangent and low linear expansion coefficient. Also disclosed is a composite woven fabric suitably used as a base material for such a printed wiring board. Specifically disclosed is a composite woven fabric containing quartz glass fibers and polyolefin fibers, in which the ratio of the quartz glass fibers to the composite woven fabric is set at 10 vol % or more and 90 vol % or less. It is preferred that the quartz glass fibers each have a filament diameter of 3 ?m or more and 16 ?m or less, and the composite woven fabric has a thickness of 200 ?m or less.

Abstract: A fused glass crucible includes a collar of doped aluminum silica that defines uppermost and outermost surfaces of the crucible. The melt line that defines the surface of molten silicon in the crucible may be substantially at the lower end of the collar or slightly above it. Crystallization of the collar makes it hard and therefore supports the remaining uncrystallized portion of the crucible above the melt line. The melt line may also be below the lower end of the collar, especially if the melt is drawn down or poured early in the process. Because there is little or no overlap or because the overlap does not last long, the doped aluminum collar is not damaged by the heat of from the melt.

Abstract: It is an object of the present invention to provide a copper-containing silica glass which emits fluorescence having a peak in a wavelength range of from 520 nm to 580 nm under irradiation of ultraviolet light with a wavelength of 400 nm or less, and which is excellent in long term stability even in the high output use. The copper-containing silica glass is made to have copper of from 5 wtppm to 200 wtppm, which emits fluorescence having a peak in a wavelength range of from 520 nm to 580 nm under irradiation of ultraviolet light with a wavelength ranging from 160 nm to 400 nm, and in which an internal transmittance per 2.5 mm thickness at a wavelength of 530 nm is 95% or more.

Abstract: It is an object of the invention to provide a synthetic silica glass for a cladding of a core from a fiber laser. The refractive index should be low and there should be no foaming foreign substances. This object is achieved by a synthetic silica glass for an optical element, which contains paramagnetic E? defect centers in an amount that is sufficient to set the absorption coefficient at 215 nm is in the range between 0.001 cm?1 and 2 cm?1; it contains paramagnetic oxygen defect centers in an amount that is sufficient to set the absorption coefficient at 250 nm is in the range between 0.001 cm?1 and 2 cm?1; the OH group concentration is 5 wtppm or less; the viscosity at 1100° C. is in the range between 1×1013.5 poise and 1×1015.5; the total content of metallic elements of Group 3 and Group 13 of the periodic table is 50.000 wtppm or less; and the relative refractive index difference of said synthetic silica glass is in the range between +0.

Abstract: A mixed quartz powder contains quartz powder and two or more types of doping element in an amount of from 0.1 to 20 mass %. The aforementioned doped elements include a first dope element selected from the group consisting of N, C and F, and a second dope element selected from the group consisting of Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, the lanthanides and the actinides. The “quartz powder” is a powder of crystalline quartz or it is a powder of glassy SiO2 particles. It is made form natural occurring quartz or it is fabricated synthetically. The “quartz powder” may be doped. The compounding ratio of the total amount (M1) of the aforementioned first elements and the total amount (M2) of the aforementioned second elements as the ratio of the number of atoms (M1)/(M2) is preferably from 0.1 to 20. Al as well as the aforementioned doped elements is preferably included in a mixed quartz powder of this invention.

Abstract: The present invention is a method for producing a silica container having a substrate containing gaseous bubbles in its outer peripheral part and an inner layer comprised of a transparent silica glass formed on an inner surface of the substrate, wherein a powdered raw material for forming a substrate containing Li, Na, and K with the total concentration of 50 or less ppm by weight and a powdered raw material for forming an inner layer containing Ca, Sr, and Ba with the total concentration of 50 to 2000 ppm by weight are prepared; a preliminarily molded substrate is formed in a frame; a preliminarily molded inner layer is formed on an inner surface of the preliminarily molded substrate; and the preliminarily molded substrate and molded inner layer are heated from inside thereof by a discharge-heat melting method under a gas atmosphere containing a hydrogen gas or a helium gas or a gas mixture thereof with the ratio of more than 10% by volume thereby making an outer peripheral part of the preliminarily molded s