Raman light scattering in nanoporous carbon obtained from silicon and titanium carbides

A study is reported on the Raman spectra of nanoporous carbon prepared in a chemical reaction from polycrystalline alpha -SiC and TiC. The spectra are shown to be of a multicomponent nature, which distinguishes this group of materials from graphites and disordered carbon structures. A series of low-frequency modes are detected. Anisotropy and dispersion effects are revealed. The results obtained argue in favor of a cluster structure of nanoporous carbon and size quantization of the electronic and vibrational spectra in carbon nanoclusters. The main structural elements of the nanoclusters in the porous framework are small fragments of bent or broken graphene sheets. The presence of fragments close in structure to strained cubic or hexagonal diamond is observed in a number of cases. (C) 2001 MAIK "Nauka/Interperiodica".