Abstract: There is here provided a method for growing single crystals from a melt which comprises the steps of preparing a double structure crucible constituted of an inner tube and an outer tube; placing a raw material in the inner tube; hermetically sealing the outer tube; and heating/melting the raw material to perform crystal growth.According to the present invention, it is possible to hermetically confine and to crystallize the raw material even at a high temperature.

Abstract: A single crystal is produced from the melt of a starting material by solidification. The process makes use of a triple-walled crucible compound of an outer cylinder made of a material selected from high-melting-point metals and alloys having a melting point of at least 1,500.degree. C., an inner cylinder made of at least one material selected from high-melting-point ceramic materials and carbon materials such as graphite, pyrolytic graphite and vitreous carbon and an intermediate cylinder made of quartz glass. The starting material is charged in the inner cylinder. The inner cylinder with the starting material charged therein is inserted in the intermediate cylinder. The intermediate cylinder with the inner cylinder hermetically inserted therein is inserted in the outer cylinder. The outer cylinder is welded to hermetically enclose the intermediate and inner cylinders therein. The thus-assembled crucible is heated to fuse the starting material, followed by crystal growth.