Relationship between the hydrodynamics in the melt and the shape of the crystal/melt interface during Czochralski growth of oxide single crystals: II. Determination of the critical rotation rate from physical simulation data on growth in the presence of simultaneous free and forced convections; comparison with experimental data on crystal growth

Abstract

The physical simulation method is used with glycerol-water model liquids imitating oxide melts in order to study the convection in the solution, the flow rate along the crucible axis and the temperature near the crystal edge with a gradual increase of the crystal rotation rate. Criteria are looked for on the basis of which it can be established when the critical rotation rate Ncrit which corresponds to a flat crystal/solution interface has been attained. A correlation is found between Ncrit and the physical and geometrical parameters of the crucible-liquid-crystal system. There is agreement between this correlation and those obtained in separate investigations on free and forced convections in the liquid during Czochralski single crystal growth [Part I, J. Crystal Growth 89 (1988) 313]. The correlation found is checked by numerous experimental data on the conditions ensuring a flat interface during the growth of single crystals of binary and complex oxides and is found to be satisfied.