Measurement of the free energy of formation of silicon carbide using liquid gold as a silicon potentiometer

Sankar Sambasivan, Christopher Capobianco, William Petuskey

Research output: Contribution to journalArticle

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Abstract

The free energies of formation of 3C- and 6H-silicon carbide were determined between 1623 and 1898 K by measuring the silicon solubility in liquid gold at equilibrium with silicon carbide and graphite. The solution behavior of the Au-Si system provides a wide compositional range for the small difference in the activity of silicon exhibited by the two polytypes, thus offering greater experimental precision over previous similar methods. For 6H-SiC, ΔG(J/mol) = -116900(±7.2) + 38.2(±4.1)T (where T is in K) relative to liquid silicon and graphite standard states is in excellent agreement with other investigations, indicating that the method is capable of determining the free energy of formation with a precision of about 0.7 kJ/mol. Our measurements on 3C-SiC exhibited greater experimental scatter, which may have been due to variations in the density of nonequilibrium defects of the crystals used, although experimental problems encountered with the complex crystal shapes may have also contributed. Nevertheless, the precision of the technique is sufficient to address some issues of polytype stability and perhaps free energy contributions of nonequilibrium defects.

Original languageEnglish (US)
Pages (from-to)397-400
Number of pages4
JournalJournal of the American Ceramic Society
Volume76
Issue number2
StatePublished - Feb 1993

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Silicon
Silicon carbide
Gold
Free energy
Graphite
Liquids
Defects
Crystals
Solubility
silicon carbide

ASJC Scopus subject areas

  • Ceramics and Composites

Cite this

Measurement of the free energy of formation of silicon carbide using liquid gold as a silicon potentiometer. / Sambasivan, Sankar; Capobianco, Christopher; Petuskey, William.

In: Journal of the American Ceramic Society, Vol. 76, No. 2, 02.1993, p. 397-400.

Research output: Contribution to journalArticle

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