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| Nanotubes | |
In 1996, researchers carried out a chemical reaction in what
may be the world's smallest set of test tubes: carbon nanotubes
with inside diameters of less than 10 nanometers and lengths of
just one micron. (A micron is a millionth of a meter.)
The ongoing research, now based at Georgia Tech, was
reported in the journal Science. Ultimately, it could have
important applications in microelectronics and other fields in
which extremely small conductors and other structures would allow
production of new types of nanoscale devices.
In related research in 1998, the same scientists moved one
step closer to a practical application for electron wave effects
in extremely small-scale circuits. In laboratory experiments,
they observed ballistic conductance — a phenomenon in which
electrons pass through a conductor without heating it — at room
temperature in multi-walled carbon nanotubes up to five microns
long. Again, the results were published in Science.
This was the first time that ballistic conductance had been
seen at any temperature in a three-dimensional system of this
scale. The ability of micron-sized structures to conduct
relatively large currents without harmful resistance heating
would allow use of the very small conductors.
Earlier this year, the researchers discovered new electronic
and micromechanical properties of the nanotubes and proposed one
application for them. In Science, they suggested a "nanobalance"
small enough to weigh viruses and other sub-micron scale
particles.
Researchers used electrical voltage to induce
electrostatic deflection and vibrational resonance in individual
carbon nanotubes. The ability to selectively deflect or induce
resonance in individual nanotubes opens new potential
micromechanical applications for the tiny structures.
Dr. Walt de Heer, a professor in the
School of Physics, and
Dr. Z.L. Wang, a professor in the
School of Materials Science and
Engineering, made the discoveries.
Courtesy Drs. Walt de Heer & Z.L. Wang
The images above show a bundle of carbon nanotubes (left), and the
same bundle to which an oscillating current has been applied
(right), causing resonance in one tube.
For more information, contact Dr. Walt de Heer, School of Physics, Georgia
Tech, Atlanta, GA 30332-0430. (Telephone: 404-894-7880) (E-mail:
deheer@electra.physics.gatech.edu); or
Dr. Z.L. Wang, School of Materials
Science and Engineering, Georgia Tech, Atlanta, GA 30332-0245. (Telephone:
404-894-8008)
(E-mail:
zhong.wang@mse.gatech.edu)
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