Polytype distribution in circumstellar silicon carbide.
Science
; 296(5574): 1852-5, 2002 Jun 07.
Article
in En
| MEDLINE
| ID: mdl-12052956
ABSTRACT
The inferred crystallographic class of circumstellar silicon carbide based on astronomical infrared spectra is controversial. We have directly determined the polytype distribution of circumstellar SiC from transmission electron microscopy of presolar silicon carbide from the Murchison carbonaceous meteorite. Only two polytypes (of a possible several hundred) were observed cubic 3C and hexagonal 2H silicon carbide and their intergrowths. We conclude that this structural simplicity is a direct consequence of the low pressures in circumstellar outflows and the corresponding low silicon carbide condensation temperatures.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Astronomy
/
Silicon Compounds
/
Carbon Compounds, Inorganic
/
Meteoroids
Language:
En
Journal:
Science
Year:
2002
Document type:
Article
Affiliation country:
United States