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Proceedings Paper

Inert gases in closed crystal growth systems
Author(s): Witold Palosz
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Paper Abstract

The effect of desorption from, and diffusion through the wall on inert gas pressure in sealed fused silica ampoules was investigated. It is shown, that desorption from the surface and the bulk of silica may lead to an accumulation of residual gas on the order of a few Torr or more upon annealing. A prior outgassing of the ampoules under vacuum at high temperature reduces the amount of gas released from the glass by at least one order of magnitude. Presence of oxide and other impurities in the source material was found to increase the residual gas pressure, affect its composition, and reduce the vapor transport rate in PVT systems. It is shown, that light gases (hydrogen, helium, and neon) diffuse through silica wall and may change the pressure inside the sealed ampoule considerably even at moderate temperatures.

Paper Details

Date Published: 7 July 1997
PDF: 10 pages
Proc. SPIE 3123, Materials Research in Low Gravity, (7 July 1997); doi: 10.1117/12.277733
Show Author Affiliations
Witold Palosz, Universities' Space Research Association/NASA Marshall Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 3123:
Materials Research in Low Gravity
Narayanan Ramachandran, Editor(s)

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