Carbon behavior at extremely high pressures, which at present cannot be investigated by direct experiments, was evaluated based on high-pressure experimental results on various SiC and NaCl-type carbides. Sixfold-coordinated carbon C(VI) was determined to be the most probable candidate for the postdiamond phase. Taking into account structural variations in the corresponding metals, the volume of C(VI) is estimated to be 3.08 cm3/mol at ambient conditions and 2.8 cm3/mol at pressures of 100–250 GPa. The postdiamond phase of C(VI) may display a greater zero-pressure bulk modulus than diamond.

This content is only available via PDF.
You do not currently have access to this content.