A modification of the Czochralski growth system consisting of a circular disk attached to the pulling rod has been used during the shouldering of Bi12SiO20 single crystals. Experimental results show significant changes to the melt-crystal interface shape and faceting behavior from the use of disks of different materials. A simple mathematical analysis of enclosure radiation provides a self-consistent explanation for the observed changes in terms of system thermal gradients and the intensity of melt convection.
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This work was supported in part by the Army High Performance Computing Research Center under the auspices of the Department of the Army, Army Research Laboratory cooperative agreement DAAH04-95-2-0003/contract DAAH04-95-C-0008, the content of which does not necessarily reflect the position or policy of the government, and no official endorsement should be inferred. Additional computational resources were provided by the University of Minnesota Supercomputer Institute. The authors gratefully acknowledge Dr. P.S. Dutta, Dr. C. Marı́n and Dr. L. Arizmendi for discussion of the experimental results and F. Abella for technical assistance in the laboratory.