Analysis of moving boundary problem of growth of Bismuth germanate crystal by heat exchanger method |
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Authors: | Jong Hoe Wang Do Hyun Kim Dae-Shik Chung |
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Affiliation: | (1) Dept. of Chem. Eng./Proc. Anal. Lab., KAIST, 305-701 Taejon, Korea;(2) Ceramics Team, RIST, 790-600 Pohang, Korea |
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Abstract: | Transient two-dimensional model of the growth of BGO crystal by heat exchanger method has been developed. A finite element
method with nonorthogonal mapping technique for the solution of the moving boundary problem is developed where the melt/solid
interface shape changes from hemispherical to planar. The moving boundary problems for the melt/solid interface location and
the temperature field were solved by two mapping rule method which enables the computation of interface shape changing from
hemispherical to planar. The maximum deflection of interface is shown when the melt/solid interface meets the corner of crucible.
As the excess heating temperature and the heat exchanger temperature were increased, more growth time for whole process is
required but the quality of BGO crystal may be improved. The ratio of the height to the radius of crucible hardly affects
the deflection of BGO melt/solid interface when it is greater than 1.5. As the cooling zone radius is decreased, maximum deflection
is decreased. The heat transfer between the crucible and the heating element should be suppressed to maximize planarity of
the interface shape. |
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Keywords: | Heat Exchanger Method Bismuth Germanate Finite Element Method Moving Boundary Problem Nonorthogonal Mapping |
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