3-DIMENSIONAL MODELING OF BI12GEO20 USING THE FLOAT-ZONE TECHNIQUE

Float zone crystal growth of Bi12GeO20 under terrestrial and micrograv ity conditions has been modeled by numerical simulation using the fini te element technique. A three-dimensional asymmetrically heated molten rod model is developed to obtain a quantitative estimate of the Rayle igh and Marangoni convection. The free surface deformation resulting f rom the combined effect of viscous, gravitational and capillary forces as a function of the temperature difference is reported. The temperat ure distribution and the flow behavior in the float zone were examined for various asymmetrical heating conditions. The results showed that nonuniform heating in the axial direction is a critical parameter for the growth of Bi12GeO20 by the float zone technique. (C) 1998 Elsevier Science B.V. All rights reserved.