A carbon electrode used for an arc discharge for manufacturing a quartz glass crucible, wherein at least one of a concave pattern and a convex pattern is formed on a surface of the carbon electrode in at least a range of 50 mm to 130 mm in a longitudinal direction of the carbon electrode from an end portion where the arc discharge takes place. Consequently, a carbon electrode that can suppress agglomeration of silica fume on the carbon electrode while manufacturing a quartz glass crucible is provided.

In an exemplary embodiment, a quartz glass crucible 1 includes: a high-aluminum-content layer 14B which is made of quartz glass having a relatively high average aluminum concentration and is provided to form an outer surface 10b of the quartz glass crucible 1; and a low-aluminum-content layer 14A which is made of quartz glass having a lower average aluminum concentration than that of the high-aluminum-content layer 14B and is provided on an inner side of the high-aluminum-content layer 14B, wherein the low-aluminum-content layer 14A includes an opaque layer 11 made of quartz glass containing a large number of minute bubbles, and the high-aluminum-content layer 14B is made of transparent or translucent quartz glass having a lower bubble content than that of the opaque layer 11. The quartz glass crucible is capable of withstanding a single crystal pull-up step undertaken for a very long period of time.

Provided are a quartz glass crucible capable of withstanding a single crystal pull-up step undertaken for a very long period of time, such as multi-pulling, and a manufacturing method thereof.

A quartz glass crucible 1 includes: a cylindrical crucible body 10 which has a bottom and is made of quartz glass; and crystallization-accelerator-containing coating films 13A and 13B which are formed on surfaces of the crucible body 10 so as to cause crystallization-accelerator-enriched layers to be formed in the vicinity of the surfaces of the crucible body 10 by heating during a step of pulling up a silicon single crystal by a Czochralski method.

A quartz glass crucible 1 having a cylindrical side wall portion 10a, a bottom portion 10b, and a corner portion 10c includes a transparent layer 11 as an innermost layer made of quartz glass, a semi-molten layer 13 as an outermost layer made of raw material silica powder solidified in a semi-molten state, and a bubble layer 12 made of quartz glass interposed therebetween. An infrared transmissivity of the corner portion 10c in a state where the semi-molten layer 13 is removed is 25 to 51%, the infrared transmissivity of the corner portion 10c in the state where the semi-molten layer 13 is removed is lower than an infrared transmissivity of the side wall portion 10a, and the infrared transmissivity of the side wall portion 10a in the state where the semi-molten layer 13 is removed is lower than an infrared transmissivity of the bottom portion 10b.

A mold for manufacturing a quartz glass crucible by a rotary molding method, having a plurality of grooves that are concentric with respect to a mold rotation axis in at least a straight body portion of an inner surface of the mold, wherein the plurality of concentric grooves are non-penetrating grooves that do not penetrate the mold. This provides a mold for manufacturing a quartz glass crucible by a rotary molding method, having an inner surface made so that it is difficult for quartz powder to slide down when forming a quartz powder compact.

In an exemplary embodiment, a quartz glass crucible 1 includes: a high-aluminum-content layer 14B which is made of quartz glass having a relatively high average aluminum concentration and is provided to form an outer surface 10b of the quartz glass crucible 1; and a low-aluminum-content layer 14A which is made of quartz glass having a lower average aluminum concentration than that of the high-aluminum-content layer 14B and is provided on an inner side of the high-aluminum-content layer 14B, wherein the low-aluminum-content layer 14A includes an opaque layer 11 made of quartz glass containing a large number of minute bubbles, and the high-aluminum-content layer 14B is made of transparent or translucent quartz glass having a lower bubble content than that of the opaque layer 11. The quartz glass crucible is capable of withstanding a single crystal pull-up step undertaken for a very long period of time.

A method for producing a round tube from a ceramic material or a glass-ceramic material or mixtures thereof is described. The method comprises introducing a silicate-ceramic, oxide-ceramic and/or non-oxide-ceramic material-forming agent into a melting vessel, which has along a longitudinal axis a tubular wall which defines a tubular cavity, wherein the melting vessel rotates about its longitudinal axis. A uniform layer of the ceramic and/or glass-ceramic material-forming agents is thereby formed, lying on the inner side of the wall, by means of centrifugal forces generated by rotation and is heated by means of a heat source arranged in the inner cavity of the melting vessel until at least the inner side of the layer of material-forming agents has melted. Such tubes can be used for various industrial purposes.

The present invention is a method for producing a quartz glass crucible for pulling a single crystal silicon from a silicon melt held therein, including the steps of: producing a quartz glass crucible having an outer layer including an opaque quartz glass containing bubbles therein and an inner layer including a transparent quartz glass containing substantially no bubbles; roughening a region of an inner surface of the produced quartz glass crucible, the region being in contact with the silicon melt when holding the silicon melt; and heating the quartz glass crucible having the roughened inner surface to crystallize a surface of the roughened region. This can produce a quartz glass crucible for pulling a single crystal silicon which can suppress generation of a brown ring on the inner surface of the crucible during pulling the single crystal silicon and can suppress crystallinity disorder of the single crystal silicon.

An infrared transmissivity measurement method is for measuring an infrared transmissivity of a quartz glass crucible which includes a transparent layer made of quartz glass that does not contain bubbles, a bubble layer formed outside the transparent layer and made of quartz glass containing bubbles, and a semi-molten layer formed outside the bubble layer and made of raw material silica powder solidified in a semi-molten state. The infrared transmissivity measurement method includes processing an outer surface of the quartz glass crucible formed by the semi-molten layer to lower a surface roughness of the outer surface; and measuring an infrared transmissivity of the quartz glass crucible based on infrared light passing through the outer surface after processing the outer surface.

A quartz glass crucible (1) includes: a crucible body (10) made of silica glass; and a crystallization-accelerator-containing layer (13) formed on an outer surface of the crucible body (10). A concentration of a crystallization accelerator contained in the crystallization-accelerator-containing layer (13) is 1.0?10.sup.13 atoms/cm.sup.2 or more and 4.8?10.sup.15 atoms/cm.sup.2 or less. The quarts glass crucible is intended to be capable of not only enduring a single crystal pulling-up process that takes a very long time, such as multi-pulling, but also stably controlling the oxygen concentration and crystal diameter of a silicon single crystal by eliminating a gap between the carbon susceptor and the crucible as much as possible.