Role of coil-crucible geometry in Czochralski bismuth germanate (BGO) crystal growth process: a thermal stress analysis

TL;DR

This study uses a numerical model to analyze how coil and crucible geometry affect electromagnetic fields, heat distribution, and thermal stress in Czochralski BGO crystal growth, aiming to optimize crystal quality.

Contribution

It introduces a 2D finite element model to compare different coil and crucible geometries and their effects on thermal stress in BGO crystal growth.

Findings

Modified geometries alter electromagnetic and heat fields

Optimized shapes improve thermal stress distribution

Two methods of stress analysis show qualitative agreement

Abstract

A numerical model of 2D finite element in a steady-state level was developed for the electromagnetic field, heat distribution, and thermal stress expansion in an oxide Czochralski crystal growth system. The extended model was employed to compare the impact of different geometries of induction coils and crucibles in the growth process. Analysis of the results emphasizes the potential of the modified geometries in alteration of the electromagnetic field and heat distribution. Consequently, the optimization of crystal/melt interface shape, thermal stress accumulation, and distribution in the growing crystal can be achieved. Finally, the proposed approaches for thermal stress calculations were compared. The outcomes showed a qualitative agreement between two methods of thermoelastic stress analysis in the calculation of stress distribution in BGO crystal.