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Proceedings Paper

Sapphire fibers grown from the melt by the EFG technique: dependence of the impurity distribution on temperature and surface tension gradients
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Paper Abstract

A stationary 2D axis-symmetric model able to evaluate the impurity distribution is developed by the finite element method for single-crystal sapphire fibers grown from the melt by the edge-defined film-fed growth (EFG) technique. The computations are carried out for two cases-one where the buoyancy is taken into account and the other where the buoyancy is neglected-using different vertical temperature gradients kg in the furnace. The dependence of the impurity distribution on kg and the Marangoni numbers Ma corresponding to the different surface tension gradients dγdT is analyzed. Computations reveal critical Marangoni numbers Mac determined by the fluid flow behavior, and that a smaller kg assures the best homogeneity of the crystal over a wide range of dγ/dT.

Paper Details

Date Published: 25 August 2008
PDF: 10 pages
Proc. SPIE 7056, Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 705603 (25 August 2008); doi: 10.1117/12.793279
Show Author Affiliations
Thomas F. George, Univ. of Missouri, St. Louis (United States)
Liliana Braescu, West Univ. of Timisoara (Romania)


Published in SPIE Proceedings Vol. 7056:
Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II
Shizhuo Yin; Ruyan Guo, Editor(s)

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