Accession Number:

AD0739183

Title:

On the Formation of Beta-SiC in the Initial Growth Stage,

Descriptive Note:

Corporate Author:

EMMANUEL COLL BOSTON MASS ORIENTAL SCIENCE RESEARCH LIBRARY

Personal Author(s):

Report Date:

1972-01-07

Pagination or Media Count:

22.0

Abstract:

The formation of Beta-SiC at temperatures outside its thermally stable range of 1,400-1,600C was studied experimentally using the sublimation procedure and the synthetic method with molten silicon. From consideration of the molar surface energy of Beta- and alpha-SiC, the following are shown to be the main causes for the phenomenon 1 Given an equal volume of crystallites, the molar surface energy of the Beta-type is always lower than that of the alpha-type based on its higher lattice symmetry 2 the bonding energy of the Beta-type is the lowest among the SiC polytypes from comparison of the band gaps 3 the rate of transition from the Beta- to the alpha-type is not too large. The free energy gaps among the SiC polytypes were found to be smaller than 100 calmole. The effects of pressure and polarity are also discussed. Author

Subject Categories:

  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE