The term amorphous carbon is restricted to the description of carbon materials with
localized π-electrons as described by P.W.Anderson (
Phys. Rev., 1958,
109, 1492). Deviations in the C–C distances greater than 5%
(i.e.
,
where
is the inter-atomic distance in the crystal lattice for the
as well as for the
configuration) occur in such materials, as well as deviations in the bond angles
because of the presence of '
dangling bonds'. The above description of amorphous carbon is not applicable to carbon materials
with two-dimensional structural elements present in all
pyrolysis residues of carbon compounds as polyaromatic layers with a nearly ideal interatomic
distance of
and an extension greater than
.