Nanotech Goes to New Lengths: Scientists Create Ultralong Carbon Nanotubes
Goho, Alexandra, Science News
Good news for Rumpelstiltskin. Scientists have made another advance toward spinning the world's strongest fibers out of molecule-thin nanotubes.
Last year, Jie Liu of Duke University in Durham, N.C., and his colleagues grew carbon nanotubes up to 4 millimeters in length (SN: 5/3/03, p. 275). Now, he and his collaborators at Los Alamos National Laboratory in New Mexico have pushed the limits of nanotube growth by a factor of 10. In the October Nature Materials, they report making carbon nanotubes a full 4 centimeters long.
Many labs around the world are producing macroscopic fibers out of carbon nanotubes. Such fibers could find applications in products ranging from power-transmission cables to lightweight aircraft materials (SN: 6/5/04, p. 363). However, the nanotubes in these fibers are short--stretching tens of microns, or about the diameter of a grain of sand. Longer nanotubes could twine into more continuous, and therefore stronger, fibers, says Liu.
Long carbon nanotubes could also be useful in producing nanoelectronic devices such as sensors and transistors. Liu says that rather than making one device at a time, manufacturers could chop a single, long nanotube into thousands of tiny devices, all with the same electronic properties.
To grow their nanotubes, Liu's team deposits iron panicles on the surface of a silicon wafer mounted inside a furnace. After ramping up the temperature to 900[degrees]C, the researchers pass a stream of gas containing ethanol molecules over the wafer. …