Supercritical fluid synthesis and possible properties of “cubic graphite”

We report on supercritical fluid synthesis of an intermediate carbon phase–austite–at a pressure of 180 MPa and temperatures 500-700$^\circ$C from soot as a precursor and supercritical carbon dioxide as a solvent. According to the results of electron and X-ray diffractions, spectral measurements and density-functional theory calculations, the observed carbon phase is proved to be cubic with a lattice parameter value of 8.96 $\pm$ 0.05 Å and a possible structural type as for KFI zeolite.