Abstract: The present invention provides a vitreous silica crucible which can suppress buckling and sidewall lowering of the crucible without fear of mixing of impurities into silicon melt. According to the present invention, provided is a vitreous silica crucible for pulling a silicon single crystal, wherein a ratio I2/I1 is 0.67 to 1.17, where I1 and I2 are area intensities of the peaks at 492 cm?1 and 606 cm?1, respectively, in Raman spectrum of vitreous silica of the region having a thickness of 2 mm from an outer surface to an inner surface of a wall of the crucible.

Abstract: A method of manufacturing of a vitreous silica crucible includes: fusing silica powder under a reduced pressure of ?50 kPa or more and less than ?95 kPa to form a transparent vitreous silica layer as an inner layer; fusing silica powder under a reduced pressure of 0 kPa or more and less than ?10 kPa to form a bubble-containing vitreous silica layer as an intermediate layer; and fusing silica powder under a reduced pressure of ?10 kPa or more and less than ?50 kPa to form a semi-transparent vitreous silica layer as an outer layer.

Abstract: Provided is a vitreous silica crucible for pulling a silicon single crystal, which stably suppresses surface vibration of a silicon melted solution filled therein and has a long life, and a method for manufacturing the same. The vitreous silica crucible for pulling a silicon single crystal includes a peripheral wall portion, a curved portion, and a bottom portion, wherein a plurality of minute concave portions are formed on a certain area of an inner surface of the peripheral wall portion, and a plurality of bubbles are formed on a lower position of the minute concave portions.

Abstract: A method of manufacturing of a vitreous silica crucible includes: fusing silica powder under a reduced pressure of ?50 kPa or more and less than ?95 kPa to form a transparent vitreous silica layer as an inner layer; fusing silica powder under a reduced pressure of 0 kPa or more and less than ?10 kPa to form a bubble-containing vitreous silica layer as an intermediate layer; and fusing silica powder under a reduced pressure of ?10 kPa or more and less than ?50 kPa to form a semi-transparent vitreous silica layer as an outer layer.

Abstract: The invention provides a chroman derivative represented by the following Formula (I) that enables the production of an SMTP compound having a desired structure: wherein, in Formula (I), each of Y1 and Y2 independently represents a hydrogen atom, a hydroxy group, an alkoxy group, an aryloxy group, or a halogen atom; each of R1 and R2 independently represents a hydrogen atom, an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a carbamoyl group; L represents an aliphatic hydrocarbon group having from 4 to 10 carbon atoms; each X independently represents a hydroxy group or a carboxy group; and n represents an integer from 0 to 2.

Abstract: Accurate temperature measurement during manufacturing a vitreous silica crucible is enabled. The present invention provides an apparatus for manufacturing a vitreous silica crucible including: a mold for forming a silica powder layer by supplying silica powder therein; an are discharge unit having carbon electrodes and a power supply unit and for heating and fusing the silica powder layer by arc discharge; and a temperature measurement unit for measuring temperature of a fused portion in the mold, wherein the temperature measurement unit is an radiation thermometer for measuring temperature by detecting radiation energy of a wavelength of 4.8 to 5.2 ?m.

Abstract: Provided is a vitreous silica crucible which can suppress inward sagging and buckling of the sidewall effectively even when time for pulling silicon ingots is extremely long. According to the present invention, provided is a vitreous silica crucible for pulling a silicon single crystal, wherein the crucible has a wall comprising, from an inner surface toward an outer surface of the crucible, a transparent vitreous silica layer having a bubble content rate of less than 0.5%, a bubble-containing vitreous silica layer having a bubble content rate of 1% or more and less than 50%, a semi-transparent vitreous silica layer having a bubble content rate of 0.5% or more and less than 1.0% and having an OH group concentration of 35 ppm or more and less than 300 ppm.

Abstract: Provided is a method of manufacturing a vitreous silica crucible for pulling a silicon single crystal which can suppress melt surface vibration of silicon melt filled therein and has a long lifetime. The crucible includes a peripheral wall portion, a curved portion and a bottom portion, and has a plurality of micro recesses on the specific region of the inner surface of the peripheral wall portion.

Abstract: There is provided a method of manufacturing a vitreous silica crucible having a suitably controlled inner surface property. The present invention provides a method of manufacturing a vitreous silica crucible by heating and fusing a silica powder layer in a rotating mold by arc discharge generated by carbon electrodes including: a preparation process for determining optimal fusing temperatures during heating and fusing the silica powder layer at plural points of different heights of the silica powder layer; a temperature measuring process for measuring actual temperatures during heating and fusing the silica powder layer at the plural points; a temperature controlling process for controlling the actual temperatures at the plural points so that the actual temperatures matches the optimal fusing temperatures at the respective points.

Abstract: The invention provides a chroman derivative represented by the following Formula (I) that enables the production of an SMTP compound having a desired structure: wherein, in Formula (I), each of Y1 and Y2 independently represents a hydrogen atom, a hydroxy group, an alkoxy group, an aryloxy group, or a halogen atom; each of R1 and R2 independently represents a hydrogen atom, an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a carbamoyl group; L represents an aliphatic hydrocarbon group having from 4 to 10 carbon atoms; each X independently represents a hydroxy group or a carboxy group; and n represents an integer from 0 to 2.

Abstract: Provided are an apparatus and a method for manufacturing a vitreous silica crucible, which enable accurate measurement of a fume generation amount, prevention of deterioration of an inner surface property, and real-time control of a raw material melting state. Provided is an apparatus for manufacturing a vitreous silica crucible 50 by supplying silica powder into a mold 10 to form a silica powder layer 11, and heating and melting the silica powder layer 11 by arc discharge. The apparatus includes the mold 10 for defining an outer shape of a vitreous silica crucible, an arc discharge unit having a plurality of carbon electrodes 13 and a power-supply unit 40, and a fume-amount measurement unit 30 for detecting an amount of fumes 80 generated in the mold 10.

Abstract: Accurate temperature measurement during manufacturing a vitreous silica crucible is enabled. The present invention provides an apparatus for manufacturing a vitreous silica crucible including: a mold for forming a silica powder layer by supplying silica powder therein; an are discharge unit having carbon electrodes and a power supply unit and for heating and fusing the silica powder layer by arc discharge; and a temperature measurement unit for measuring temperature of a fused portion in the mold, wherein the temperature measurement unit is an radiation thermometer for measuring temperature by detecting radiation energy of a wavelength of 4.8 to 5.2 ?m.

Abstract: The present invention provides a method of manufacturing a vitreous silica crucible including: a silica powder supplying process of supplying a material silica powder into a mold for molding a crucible, to form a silica powder layer, and an arc fusing process of arc fusing the silica powder layer by arc discharge generated by carbon electrodes, wherein the arc fusing process includes processes of measuring a temperature of the silica powder layer, and controlling a vitreous silica fused state based on a reference temperature which is a temperature at a local maximum point which appears first in the arc fusing process.

Abstract: Provided is a method of calculating a temperature distribution with higher accuracy than a conventional method, which calculates a temperature distribution of an inner surface of a silica powder molded body during manufacturing based on boundary conditions corrected in accordance with the actually measured temperature in consideration of plasma radiation by arc discharge and heat radiation of arc discharge.

Abstract: There are provided an apparatus and a method for manufacturing a vitreous silica crucible which can prevent the deterioration of the inner surface property in the manufacturing process of a vitreous silica crucible. The apparatus includes a mold defining an outer shape of a vitreous silica crucible, and an arc discharge unit having electrodes and a power-supply unit, wherein each of the electrodes includes a tip end directed to the mold, the other end opposite to the tip end, and a bent portion provided between the tip end and the other end.

Abstract: The present invention provides a method of manufacturing a vitreous silica crucible by heating and fusing a silica powder layer in a rotating mold by arc discharge generated by carbon electrodes comprising: a preparation process for determining optimal temperatures during heating and fusing the silica powder layer for one or more selected from the group consisting of the silica powder layer, fume generated during arc fusing, and arc flame generated in the arc discharge; a temperature measuring process for measuring actual temperatures during heating and fusing for one or more selected from the group where the optimal temperatures are determined; and a temperature controlling process for controlling the actual temperatures for one or more selected from the group where the actual temperatures are measured so that the actual temperatures match the optimal temperatures.

Abstract: The present invention provides a method of manufacturing a vitreous silica crucible including: a silica powder supplying process of supplying a material silica powder into a mold for molding a vitreous silica crucible, to form a silica powder layer, and an arc fusing process of arc fusing the silica powder layer by arc discharge generated by carbon electrodes, wherein the arc fusing process includes processes of measuring temperatures at measuring points provided on different heights of an inner surface of the silica powder layer while rotating the mold, and controlling the arc discharge to enable detection, at each measuring point, of a local maximum point which appears first in the arc fusing process.

Abstract: Provided is a vitreous silica crucible for pulling a silicon single crystal, which stably suppresses surface vibration of a silicon melted solution filled therein and has a long life, and a method for manufacturing the same. The vitreous silica crucible for pulling a silicon single crystal includes a peripheral wall portion, a curved portion, and a bottom portion, wherein a plurality of minute concave portions are formed on a certain area of an inner surface of the peripheral wall portion, and a plurality of bubbles are formed on a lower position of the minute concave portions.

Abstract: Provided is a method of manufacturing a vitreous silica crucible for pulling a silicon single crystal which can suppress melt surface vibration of silicon melt filled therein and has a long lifetime. The crucible includes a peripheral wall portion, a curved portion and a bottom portion, and has a plurality of micro recesses on the specific region of the inner surface of the peripheral wall portion.

Abstract: Accurate temperature measurement during manufacturing a vitreous silica crucible is enabled. The present invention provides an apparatus for manufacturing a vitreous silica crucible including: a mold for forming a silica powder layer by supplying silica powder therein; an arc discharge unit having carbon electrodes and a power supply unit and for heating and fusing the silica powder layer by arc discharge; and a temperature measurement unit for measuring temperature of a fused portion in the mold, wherein the temperature measurement unit is an radiation thermometer for measuring temperature by detecting radiation energy of a wavelength of 4.8 to 5.2 ?m.