Three-dimensional analysis of heat flow, segregation, and interface shape of gradient-freeze crystal growth in a centrifuge

Three-dimensional (3D) heat flow, dopant segregation, and interface shape d uring crystal growth by a gradient freeze technique in a centrifuge are ana lyzed by a finite volume method. The basic flow patterns for a fixed geomet ry (with a concave interface) at different configurations agree well with t he previous report (Friedrich et al., J. Crystal Growth 167 (1996) 45). How ever, the self-consistent analysis allows us for the first time to further investigate the role of the Coriolis force and centrifugal acceleration on the heat and mass transfer and the interface, simultaneously. Furthermore, the rotation speed found for the weakest convection, where the Coriolis for ce balances the gravitational and centrifugal farces, turns out to have lar ger radial segregation, despite having a larger effective segregation coeff icient. Rotation about the growth axis is also investigated. For this confi guration, it is found that both axial and radial segregation could be reduc ed under certain conditions. (C) 2001 Elsevier Science B.V. All rights rese rved.