IL --- August 04, 2005 --- The newest promising
material for advanced technology applications is
diamond nanotubes, and research at the U.S. Department
of Energy's Argonne National Laboratory is giving
new insight into the nature of nanodiamond.
Argonne researcher Amanda Barnard, theorist in the Center
for Nanoscale Materials , is working with colleagues at two Italian universities
who produced innovative diamond-coated nanotubes.
The diamond-coated tubes resemble a stick of rock candy, holding a layer of
diamond 20 to 100 nm thick. A nanometer is one millionth of a millimeter. The
period at the end of this sentence is about one million nanometers long. The
technology in its fledgling state has already caught the eye of the electronics
industry for the promise of ultra-thin televisions with cathode-ray-tube-like
quality picture at a fraction of today's current flat-panel television costs.
Diamond offers an amazing array of medical and technological possibilities.
Wire molecules can be attached to it, and diamond has superior light emission
properties. While diamond is an insulating material, the surface is highly
electronegative. A nanodiamond coating consists of pure surface diamond. This
gives a diamond-coated nanowire conductance from the nanotubes and the superior
conduction from the diamond. Add to this superior light-emission properties
and very low voltage requirements, and the possibility exists for very flat,
''By using a more efficient conductor, nanotubes, with a more efficient field
emitter, in this case nanodiamonds, you get more efficient devices,'' said
Barnard. ''A lot of groups are looking for something better to make electronic
displays out of, and this is just another candidate that looks very promising.''
Researchers from the University La Sapienza and
the University Tor Vergata discovered
the ability for a nanotube to grow nanodiamond under certain conditions in
2004, but did not know the specifics of how the diamond grew. To better understand
the conditions that brought them their discovery, researchers from the group
brought their discovery to Barnard.
Barnard, a postdoc from the Royal Melbourne
Institute of Technology University , published her original results on
the modeling of diamond nanowires in the October 2003 issue of Nano Letters.
Her theories earned her the recognition of the Italian group, and she was approached
in March of 2004 to help with calculations on their discovery.
''They could make them, but they couldn't understand exactly what was happening
or how they were forming,'' said Barnard.''They knew what it was, they could
characterize it, but they didn't know how the growth progressed.''
Barnard calculated that during the process of etching – the term for the degradation
of nanotubes – atomic hydrogen can change the hybridization of chemical bonds
between carbon atoms of a nanotube.
''Traditionally in a hydrogen environment carbon nanotubes would fall apart
and disintegrate," she said, "but something different was happening. We actually
established that if the amount of hydrogen present [is in correct proportion],
the defects that form will nucleate into diamond before there is a chance to
These imperfections that form uniformly across the nanotube's surface allow
for the bonding of diamond molecules, which then begin to grow the length of
the tube. An added bonus property is that the end of the nanotube is coated
with a thicker bulb of nanodiamond, and upon formation the structures stand
upright without manipulation.
Barnard will leave Argonne in August for a fellowship at Oxford University,
but will continue to conduct research at the Center for Nanoscale Materials,
now under construction. Barnard has great expectations for the opportunities
the new center will open up for nanoscale research.
''I hope that the CNM will give me more opportunity to collaborate with experimental
groups,'' said Barnard. ''I am a great advocate of doing experimentally relevant
theory, and the CNM will be a great place for doing that.''
About Argonne National Laboratory:
The nation's first national laboratory, Argonne National Laboratory conducts
basic and applied scientific research across a wide spectrum of disciplines,
ranging from high-energy physics to climatology and biotechnology. Since 1990,
Argonne has worked with more than 600 companies and numerous federal agencies
and other organizations to help advance America's scientific leadership and
prepare the nation for the future. Argonne is operated by the University of
Chicago for the U.S. Department of Energy's Office of Science.
For more information visit www.anl.gov