The combination of sp3, sp2 and sp hybridized atoms can give rise to a large
number of carbon allotropic forms and phases, but only carbon solids based
on all sp3 (diamond) and sp2 (graphite, fullerene) hybridization are well
known and characterized [1]. In addition there are innumerable transitional
forms of carbon where sp2 and sp3 hybridization bonds co-exist in the samesolid such as in amorphous carbon, carbon black, soot, cokes, glassy carbon
etc [2-4].