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.
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,
where
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is the inter-atomic distance in the crystal lattice for the
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as well as for the
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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
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and an extension greater than
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.