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Fun With Nanotechnology Advances
wieselwerkstatte sent us a link to a Nature article that talks about the possibilty for self-soldering molecular wires. In related news, demon-cw sent us a C't story about .2 buckyballs that they are using to create nanotubes. Use the fish for those who don't speak German.
Smaller is not possible
Michaela Simon 02.11.2000
A carbon tube with a diameter of 4*10^-10m (= 0.4nm)
The Nobel Price 1996 for Chhemistry was awarded for the discovery of a soccer ball - a very small one though. The "Buckyball" only consists of 60 carbon atoms. Its synthesis and detection awarded Robert F. Curl, Harold W. Kroto und Richard E. Smalley the price.
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The atoms of this molecule are placed exactly like the sextangular leather patches of a soccer ball. With this C60 is another modification of carbon among graphite and diamond. Until now quite a number of carbon spheres of different sizes have been found. The smallest one of this Fullerenes called class of carbon molecules - the C20 - was just recently described in the magazine Nature (2000, 407, S.60-63.).
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A few years ago there was quite an euphoria about C60 and relatives, and its applications in various areas of science was lively discussed (e.g. superconduction and HIV proteasis inhibition). Even if today anyone can order C60 in chemistry wholesale shops ($500 per gramm) there never was a real technological breakthrough.
The latter is hoped to come with carbon nanotubes - molecules formed like tubes that consist exclusively of carbon (like C60). These tubes were discovered 1991 by the Japanese researcher Sumio Iijima. Nanotube research started as offspring of Fullerene chemistry and is on its best way to surpass it.
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Carbon nanotubes consist of concentric graphite shells - between one and fifty of them which gives a diameter of 1-50nm. But nanotubes can be up to a millimetre in length - and it is this anisotropy that is of importance for applications. Fibers made of nanotubes are said to have an enormous tensile strength (100times stronger than steel with 1/16th of steel's weight). The interior of these tubes can be filled with various material (e.g. hydrogen) - even chemical reactions are possible within these miniature test-tubes.
Because of teir special electronic properties these tubes could become an important part of future nano technology.
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In today's issue of Nature two research groups from Hongkong and Japan report independently about the(ir) world smallest nanotube (Nature, 2000, 408, S. 50 und S. 51). It only has a radius of 0.2 nm (nanometers, 2*10^-10m). According to theory scientists this radius is the ultimate as smaller tubes won't be stable any more.
The extreme curvature of the carbon shells creates unusual physical properties: along the axis these tubes a metal-like conductivity is postulated. Further properties of this smallest of all nanotubes have to be researched, but be prepared for suprprise.