It is difficult to denote a boundary between all the carbon allotropes.=20
Diamond is easy, as is graphite: the sheets are planar. The most perfect=20
graphite brand is HOPG (highly ordered pyro graphite, used as SPM=20
standard substrate, and in xray monochromators), whereas the carbon=20
in soot has a semimorphous, turbostratic order of graphite sheets.=20
Buckyballs are easy to spot, but what are buckytubes? I don't think=20
one can call them graphite, since curvature of the concentric sheets is=20
quite large.
Btw carbon fibre production, they first used PAN (polyacrylnitrile)=20
fiber, baked in an oven under tensile load/inert atmosphere. Afair best=20
carbon fibre grade is now spun from coal tar (I know how this sounds...).=
=20
I don't know how the bucky tubes are produced. At a guess, grown from=20
gas phase, using transition metal (nickel?) catalysis?
ciao,
'gene