Thermal Analysis of Coil-Crucible Configurations in Czochralski Growth of BGO Crystals

This study presents a detailed numerical investigation into the influence of coil-crucible configurations on electromagnetic heating, thermal transport, and stress development during the Czochralski (Cz) growth of bismuth germanate (BGO) crystals. A two-dimensional steady-state finite element model is developed to simulate the coupled behavior of electromagnetic fields, fluid flow, heat conduction, and thermoelastic deformation in both the melt and solid domains. Three distinct coil-crucible arrangements are analyzed to evaluate their effects on the temperature field, melt convection patterns, and the morphology of the crystal-melt interface. The results reveal that strategic modifications in geometry can significantly enhance temperature uniformity while mitigating the magnitude and localization of thermally induced stress within the growing crystal-factors that are critical for reducing defect formation such as dislocations and cracks. Additionally, the study compares two thermal stress estimation approaches, providing a detailed assessment of the resulting stress fields. Validation against available experimental data and literature benchmarks confirms the reliability of the model and underscores the pivotal role of thermal system design in improving crystal quality. These insights provide a practical framework for optimizing coil-crucible configurations to achieve higher-quality oxide crystals in industrial Czochralski growth systems.