Synthesis of carbon polymorphs through the decomposition of metal carbides was studied employing hydrothermal technique in the pressure and temperature ranges of 100-200 MPa and 350-800°C respectively. It was observed that dissociation of β-SiC into SiO2 occurred in the presence of organic compounds and controlled free elemental carbon phase formation. The organic compounds are known to dissociate at low temperature to C-O-H supercritical fluids under supercritical hydrothermal condition which have great influence on the decomposition of metal carbides. The scanning electron microscopic (SEM) studies of β-SiC-organic compounds system reveal that the bulk of the carbon particles formed are spherical or ovoid shaped particles and in some runs, the authors find the formation of nanosized octahedral crystallites at the inner walls of the hallow spherical carbon particles exhibiting sp3 hybridisation. The microRaman spectral studies of carbon crystallites reveal that they have typical spectra of sp3 hybridisation, which clearly demonstrates the formation of nanosized diamond crystallites. The X-ray diffraction studies of the silicon carbide-water experimental run products shows only the lines of silica which are either quartz or cristobalite phase and no traces of carbon were seen.
All Science Journal Classification (ASJC) codes