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In-Situ Pressure Measurements During the Detached Growth of GermaniumCrystal growth by the vertical Bridgman method in which there is little or no contact between the wall and the crystal has been termed detached solidification. Detachment has been observed frequently in previous microgravity experiments, and has been reported under some terrestrial conditions as well. It is expected that detachment can be conditioned by establishing an appropriate pressure difference below and above the melt. To test this hypothesis, an experimental technique has been developed to measure this pressure difference during the growth of germanium by the vertical Bridgman method. The apparatus allows for both monitoring the pressures and actively controlling them during growth. For a given melt height, there is a maximum pressure difference attainable before gas bubbles up through the melt. This maximum pressure increases with increasing melt height. As the melt height approaches zero, the maximum pressure difference, about 20 mbar in these experiments, is determined by the surface tension and gap width of the meniscus at the bottom of the melt.
Document ID
20030065908
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Volz, M. P.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Palosz, W.
(Universities Space Research Association Huntsville, AL, United States)
Szofran, F. R.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Metals And Metallic Materials
Meeting Information
Meeting: Microgravity Transport Processes in Fluid, Thermal, Biological and Materials Sciences Conference III
Location: Davos
Country: Switzerland
Start Date: September 14, 2003
End Date: September 19, 2003
Distribution Limits
Public
Copyright
Other

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