Crystal growth under heat field rotation conditions

Abstract

Rotation of the heat field which is applied to the outer walls of a crystallizer or growth crucible, provides a contact-free induction of forced convection (i.e. flow azimuthal component) in a medium of crystallization. Thus, the stirring of a melt or solution is gained without the direct effect of a rotating crystal, or crucible, or various mixers. This allows to simplify crystallization and to escape vibration and other excitations. The circular movement of a heat field by the perimeter of a growing crystal, which proceeds at a certain amplitude and frequency, provides the formation of a structurally perfect single crystal. An original heating furnace provides the rotation of the heat field. Thermal control of this furnace allows maintainance of a necessary temperature in a growth zone with high precision; it is possible to set the amplitude and frequency of thermal oscillation in a wide range of values. This technique was tested for the growth of nonlinear-optical CLBO crystals from a high-temperature melt-solution and KDP crystals from a water solution.