ELECTRONIC STRUCTURE OF VARIOUS FORMS OF SOLID STATE CARBONS. GRAPHITE INTERCALATION COMPOUNDS

The study of carbons in the solid state implies an examination of the bond between neighbouring carbons and of its variability. The relationship between actual bonds and the hybridisation of atomic orbitals (AO) which represents them is then examined, as well as the formation of electronic conduction bands. The advantages and limits of the different models -more or less simplified -which have been used to investigate the band structure and/or the electronic states of graphite, of point defect in graphite, of its intercalation compounds, and of disordered carbons, are described. Some magnetic methods of investigation, namely static magnetic susceptibility, -sensitive to the donor or acceptor nature of any foreign atoms present -, nuclear magnetic resonance (NMR)- using the nucleus of certain atoms as probes for the study of the conduction bands near the Fermi level-, and electron paramagnetic resonance (EPR) -sensitive to the delocalisation of electrons and also to the presence of certain types of defects -are then presented.