Dieter M. Gruen, Materials Science Division, Argonne National
Laboratory
Fullerenes, nanotubes and ultrananocrystalline diamond:
There's a bit less room at the bottom*
Where did they come from? Where are
they going? These three nanostructured forms of carbon were discovered between
1985 and 1994 opening new vistas for cross cutting work in several disciplines
including physics, chemistry, biology and materials science. The discovery of
these substances, which had eluded detection despite the enormous amount of work
that had been done on carbon by generations of scientists, helped both to spark
and to emphasize the importance of nanoscience which was just beginning to
emerge as a discipline in its own right during that period.
It has turned out that the three nanocarbons are exemplars par excellence of the
profound changes in properties that occur when materials reach single digit
nanometer dimensions. And size matters in a most profound way in the case of
carbon because uniquely the sp2 and sp3 configurations differ by only 0.02ev in
this element. Consequently, relatively small, size dependent complex changes in
bond hybridization, influenced as well by curvature, steric and other factors
are responsible for carbon nanostructures with vastly different physical and
chemical properties. Furthermore, because of the close energetic relationships,
kinetic factors strongly influence the product channels that determine the
outcome of experiments designed to synthesize one or another of the three forms.
One can arrange matters such that the simultaneous synthesis of more than one of
these forms is possible resulting surprisingly in a �self composite� material.
In this colloquium, I will attempt to convey some of the excitement many of us
working in this field feel because of the abundance of new science that
continues to be produced. I will illustrate the basis for this feeling with
examples to try to convince you that fullerenes, nanotubes, and
ultrananocrystalline diamond in film and disperse forms occupy significant
positions in the spacious �room at the bottom�.
*Work performed under the auspices of the U.S. Department of Energy, BES-Materials
Sciences,under Contract W-31-109-ENG-38