Chirality problem of nanotubes solved by group of scientists
U.S. based team led by Professor Chongwu Zhou of the USC Viterbi School of Engineering and Ming Zheng of the National Institute of Standards and Technology in Maryland solved the problem by inventing a system that consistently produces carbon nanotubes of a predictable diameter and chirality.
Explanation of chirality : If you took a sheet of notebook paper and rolled it straight up into a tube, it would have a certain chirality. If you rolled that same sheet up at an angle, it would have a different chirality. In this example, the notebook paper represents a sheet of latticed carbon atoms that are rolled up to create a nanotube.
“Controlling the chirality of carbon nanotubes has been a dream for many researchers. Now the dream has come true,” Zhou says.
The release explains Carbon nanotubes are typically grown using a chemical vapour deposition (CVD) system in which a chemical-laced gas is pumped into a chamber containing substrates with metal catalyst nanoparticles, upon which the nanotubes grow. It is generally believed that the diameters of the nanotubes are determined by the size of the catalytic metal nanoparticles. However, attempts to control the catalysts in hopes of achieving chirality-controlled nanotube growth have not been successful.
To overcome this, the USC team’s approach is to use a technique similar to vapour phase epitaxy (VPE).
Further details of this research have been published in the paper, "Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy," by Jia Liu et al in Nature Communications, 3, 1199. DOI:10.1038/ncomms2205