IN-SITU DIAGNOSIS AND CONTROL OF CRYSTAL GROWTH PROCESS BY MEANS OF ELECTRIC POTENTIALS

Abstract

The paper discussed a possibility of using new approaches for in-situ diagnosis growth processes of large crystals as well as solving some specific problems of controlling them. They are based on the current monitoring of changes in the differences of electric potential between growing crystals and crystallization medium. It is obvious that this monitoring reflects such important crystallization processes as accumulation of charge at the crystal interface and electric screening of it, growth of concentration of subphase formation at the interface (later, inclusions), current change in the mass crystallization rate, etc. This change in the rate suggests a new concept of automation of crystal growth processes, based on minimization of the difference in the current and initially predetermined change in Δϕ through inversely-related adjustment of the temperature of crystallization medium. We have experimentally substantiated the possibility of using various outer electric potentials for modification of processes in a double electric layer at the interface and extension of growth period under fairly favorable conditions. The system of low-temperature phase of barium metaborate crystal and molten solution as crystallization medium was taken for a model one.