Produced is a large single crystal with no crystal grain boundary, which is a high-quality single crystal that has a uniform composition in both the vertical and horizontal directions at an optimum dopant concentration. Provided is a single-crystal production equipment including, at least: a granular raw material supply apparatus which supplies a certain amount of a granular raw material downward; a granular raw material melting apparatus which heats and melts the granular raw material and supplies the thus obtained raw material melt downward; and a crystallization apparatus which allows a single crystal to precipitate out of a mixed melt that is formed upon receiving a melt formed by irradiating an infrared ray from a first infrared ray irradiation equipment to the upper surface of a seed single crystal and the raw material melt supplied from the granular raw material melting apparatus.

A method for producing or repairing a three-dimensional work piece, the method comprising the following steps: providing at least one substrate (15); depositing a first layer of a raw material powder onto the substrate (15); and irradiating selected areas of the deposited raw material powder layer with an electromagnetic or particle radiation beam (22) in a site selective manner in accordance with an irradiation pattern which corresponds to a geometry of at least part of a layer of the three-dimensional work piece to be produced, wherein the irradiation is controlled so as to produce a metallurgical bond between the substrate (15) and the raw material powder layer deposited thereon. Moreover, a use and apparatus are likewise disclosed.

A method for producing or repairing a three-dimensional work piece, the method comprising the following steps: providing at least one substrate (15); depositing a first layer of a raw material powder onto the substrate (15); and irradiating selected areas of the deposited raw material powder layer with an electromagnetic or particle radiation beam (22) in a site selective manner in accordance with an irradiation pattern which corresponds to a geometry of at least part of a layer of the three-dimensional work piece to be produced, wherein the irradiation is controlled so as to produce a metallurgical bond between the substrate (15) and the raw material powder layer deposited thereon. Moreover, a use and apparatus are likewise disclosed.

In the present invention, once a polycrystalline silicon rod is grown by the Siemens process, the polycrystalline silicon rod is heat-treated within a temperature range from 750 C. to 900 C. to relieve residual stress in the crystal. According to the experiment of the present inventors, residual stress can be relieved satisfactorily by heat treatment at the above-described low temperature, and in addition, metal contamination cannot be induced and the physical properties of the polycrystalline silicon rod cannot be changed. The above heat treatment can be conducted inside a furnace used to grow the polycrystalline silicon rod, and can also be conducted outside a furnace used to grow the polycrystalline silicon rod. According to the present invention, a polycrystalline silicon rod with residual stress () of not more than +20 MPa evaluated by a 2-sin.sup.2 diagram can be obtained.

In the present invention, once a polycrystalline silicon rod is grown by the Siemens process, the polycrystalline silicon rod is heat-treated within a temperature range from 750 C. to 900 C. to relieve residual stress in the crystal. According to the experiment of the present inventors, residual stress can be relieved satisfactorily by heat treatment at the above-described low temperature, and in addition, metal contamination cannot be induced and the physical properties of the polycrystalline silicon rod cannot be changed. The above heat treatment can be conducted inside a furnace used to grow the polycrystalline silicon rod, and can also be conducted outside a furnace used to grow the polycrystalline silicon rod. According to the present invention, a polycrystalline silicon rod with residual stress () of not more than +20 MPa evaluated by a 2-sin.sup.2 diagram can be obtained.

Provided is a method for manufacturing a synthetic gemstone, which manufactures a synthetic gemstone from a body tissue separated from a person or an animal, the method including: extracting a biological material from the body tissue; preparing a mixed material by mixing the biological material with a gemstone material; and growing a synthetic gemstone on a crystal seed as a single crystal by melting the mixed material.

Provided is a method for manufacturing a synthetic gemstone, which manufactures a synthetic gemstone from a body tissue separated from a person or an animal, the method including: extracting a biological material from the body tissue; preparing a mixed material by mixing the biological material with a gemstone material; and growing a synthetic gemstone on a crystal seed as a single crystal by melting the mixed material.

Produced is a large single crystal with no crystal grain boundary, which is a high-quality single crystal that has a uniform composition in both the vertical and horizontal directions at an optimum dopant concentration and contains only a small number of negative crystals and exsolution lamellae. A single-crystal production equipment includes at least: a quartz crucible in which a seed crystal is placed on its bottom; a powder raw material supply apparatus which supplies a powder raw material into the quartz crucible; and an infrared ray irradiation apparatus which applies an infrared ray to the powder raw material supplied into the quartz crucible from the powder raw material supply apparatus.

Produced is a large single crystal with no crystal grain boundary, which is a high-quality single crystal that has a uniform composition in both the vertical and horizontal directions at an optimum dopant concentration and contains only a small number of negative crystals and exsolution lamellae. A single-crystal production equipment includes at least: a quartz crucible in which a seed crystal is placed on its bottom; a powder raw material supply apparatus which supplies a powder raw material into the quartz crucible; and an infrared ray irradiation apparatus which applies an infrared ray to the powder raw material supplied into the quartz crucible from the powder raw material supply apparatus.

Provided is a method for manufacturing a synthetic gemstone, which manufactures a synthetic gemstone from a body tissue separated from a person or an animal, the method including: extracting a biological material from the body tissue; preparing a mixed material by mixing the biological material with a gemstone material; and growing a synthetic gemstone on a crystal seed as a single crystal by melting the mixed material.