One aspect relates to a process for the preparation of a quartz glass body, including providing a silicon dioxide granulate, 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 silicon dioxide granulate is obtained by providing and processing a silicon dioxide powder. One aspect also relates to silicon dioxide granulate, which is obtained by providing a silicon dioxide powder and processing it. One aspect further relates to a quartz glass body which is obtainable by this process. One aspect further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

One aspect relates to a process for the preparation of a quartz glass body, including providing a silicon dioxide granulate, 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 silicon dioxide granulate is obtained by providing and processing a silicon dioxide powder. One aspect also relates to silicon dioxide granulate, which is obtained by providing a silicon dioxide powder and processing it. One aspect further relates to a quartz glass body which is obtainable by this process. One aspect further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

In an exemplary embodiment, a quartz glass crucible 1 includes: a cylindrical crucible body 10 which has a bottom and is made of quartz glass; and a first crystallization-accelerator-containing coating film 13A which is formed on an inner surface 10a so as to cause an inner crystal layer composed of an aggregate of dome-shaped or columnar crystal grains to be formed on a surface-layer portion of the inner surface 10a of the crucible body 10 by heating during a step of pulling up the silicon single crystal by a Czochralski method. The quartz glass crucible is capable of withstanding a single crystal pull-up step undertaken for a very long period of time.

In an exemplary embodiment, a quartz glass crucible 1 includes: a cylindrical crucible body 10 which has a bottom and is made of quartz glass; and a first crystallization-accelerator-containing coating film 13A which is formed on an inner surface 10a so as to cause an inner crystal layer composed of an aggregate of dome-shaped or columnar crystal grains to be formed on a surface-layer portion of the inner surface 10a of the crucible body 10 by heating during a step of pulling up the silicon single crystal by a Czochralski method. The quartz glass crucible is capable of withstanding a single crystal pull-up step undertaken for a very long period of time.

A quartz glass body and a process for the preparation of a quartz glass body is disclosed. In one aspect, the process includes providing a silicon dioxide granulate from a pyrogenic silicon dioxide powder, 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. In at least one process a silicon component different from silicon dioxide is added. One aspect further relates to a quartz glass body which is obtainable by this process. A light guide, an illuminant and a formed body, are each obtainable by further processing of the quartz glass body.

A quartz glass body and a process for the preparation of a quartz glass body is disclosed. In one aspect, the process includes providing a silicon dioxide granulate from a pyrogenic silicon dioxide powder, 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. In at least one process a silicon component different from silicon dioxide is added. One aspect further relates to a quartz glass body which is obtainable by this process. A light guide, an illuminant and a formed body, are each obtainable by further processing of the quartz glass body.

One aspect is an oven including a melting crucible with a crucible wall, a solids feed with an outlet, a gas inlet and a gas outlet, wherein in the melting crucible the gas inlet is arranged below the solids feed outlet and the gas outlet is arranged at the same height as or above the solids feed outlet. One aspect further relates to a process for making a quartz glass body, including providing and introducing a bulk material selected from silicon dioxide granulate and quartz glass grain into the oven and providing a gas, making a glass melt from the bulk material, and making a quartz glass body from at least a part of the glass melt. One aspect relates to a quartz glass body obtainable by this process and a light guide, an illuminant and a formed body which are each obtainable by processing the quartz glass body further.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt from the silicon dioxide granulate in an oven, and iii.) Making a quartz glass body from at least a part of the glass melt, wherein the oven comprises a hanging sinter crucible. The invention also relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body which are each obtainable by further processing the quartz glass body.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing silicon dioxide particles, ii.) Making a glass melt out of the silicon dioxide particles in an oven and iii.) Making a quartz glass body out of at least part of the glass melt, wherein the oven has a gas outlet through which gas is removed from the oven, wherein the dew point of the gas on exiting the oven through the gas outlet is less than 0 C. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

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.