NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
CBr4 vapor growth morphologies near the polymorphic transition point. I - Single crystals. II - Crystals with large-angle grain boundariesHigh-resolution microscopy and image processing were used to investigate morphological changes in CBr4 single crystals during growth from the vapor at various levels of supersaturation and at temperatures below the compound's polymorphic phase transition. It was found that, as the temperature increased at fixed supersaturations, the corners of the crystals became rounded as a result of thermal roughening; the rounding temperatures were different for crystallographically different corners. A study of CBr4 crystals with large-angle grain boundaries or twin boundaries (extended macrodefects), conducted at the temperature of polymorphic phase transition showed that the phase transition temperature, T(tr) and crystal surface morphology of these crystals depended on the presence or absence of extended macrodefects. Unlike the case of a perfect single crystal, where the T(tr) was about 46.75 C, the phase transition in crystals with extended macrodefects occurred significantly below 46.75.
Document ID
19920042983
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Xiao, Rong-Fu
(NASA Langley Research Center Hampton, VA, United States)
Rosenberger, Franz
(Alabama, University Huntsville, United States)
Date Acquired
August 15, 2013
Publication Date
December 1, 1991
Publication Information
Publication: Journal of Crystal Growth
Volume: 114
Issue: 4 De
ISSN: 0022-0248
Subject Category
Materials Processing
Accession Number
92A25607
Funding Number(s)
CONTRACT_GRANT: NSF INT-89-03173
CONTRACT_GRANT: NAG1-972
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available