Arrangement of C atoms in the SiC-C solid solution.
The microstructure of a silicon carbide-carbon solid-solution powder (SiC-C), obtained from a fine powder of silicon and thermal expansive graphite, is investigated by X-ray powder diffraction methods. The microstructure is characterized by Williamson-Hall analysis and the strain-field model suggested by van Berkum et al. [Acta Cryst. (1996), A52, 730-747]. SiC-C adopts a layered structure like the solid solutions formed by compounds possessing a diamond-like structure, e.g. SiC-AlN. Superstoichiometric C atoms are located as planar defects. The SiC-C solid solution is destroyed on heating in a vacuum in the temperature range of graphitization of diamond but is maintained after sintering at high pressure (4-8 GPa) and high temperature (1673 and 2073 K). However, at the higher temperature (2073 K), it is observed that planar defects formed by C atoms decompose to non-correlated point defects accompanied simultaneously by a decrease in the lattice parameter from 4.3540 (2) to 4.35234 (5) Å.
Mykhaylyk
OO
Institute for Problems of Materials Science, Ukrainian National Academy of Sciences, Krzhyzhanivskogo 3, 252180 Kyiv, Ukraine. oom65@usa.net
Gadzira
MP