Abstract: In the method for growing large-volume monocrystals crystal raw material is heated in a melting vessel with heating elements to a temperature above its melting point until a melt is formed. A monocrystal is then formed on the bottom of the melting vessel by lowering the temperature at least to the crystallization point. A solid/liquid phase boundary is formed between the monocrystal and the melt. The monocrystal grows towards the melt surface in a direction that is perpendicular to the phase boundary. A vertical axial temperature gradient is produced and maintained between the bottom of the melting vessel and its upper opening and heat inflow and/or heat outflow through side walls of the melting vessel is prevented, so that the solid/liquid phase boundary has a curvature radius of at least one meter. A crystal-growing device for performing this process is also described.

Abstract: The invention relates to a method for growing large-volume monocrystals with a uniform orientation and consisting of a melt of crystal raw material, in a device comprising a sealable housing (10) in which a melting vessel (20) with side walls (22), a bottom (24), a top opening (26) facing said bottom (24) and optionally a lid (28) are located; and at least one heating element (50, 50′). According to said method, a crystal raw material in the melting vessel (20) is heated with heating elements (50, 50′) to a temperature above the melting point until a melt with a surface is formed. A monocrystal is then formed on the bottom of the melting vessel by lowering the temperature to at least the crystallisation point. Said monocrystal forms a solid/liquid interphase with the melt and grows towards the melt surface on said interphase, in a direction that is perpendicular to the interphase.

Abstract: A glass melting tank with at least one pair of heating electrodes projecting into the glass melt and a process for melting glass are described. The glass melting tank has, at least in the area of the melt, a narrowed cross section area and the glass melting tank has at least one heating electrode in front of and a corresponding heating electrode behind the narrowed cross section area and in this way an increase in the temperature of the melt can be achieved in the narrowed area. A preferred application is the refining of glass melts.