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.