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.
