2007 Balzan Prize for Nanoscience
Nanoscience studies the physical and chemical properties of materials characterized by structure at the scale of one or a few nanometres (a nanometre is one millionth of a millimetre). On this scale, corresponding to the dimension of a few atoms, quantum effects become important and lead to unexpected and technically interesting properties. Among the many structures investigated in the last few decades, carbon nanotubes have proven to be the most promising, and are actively investigated in many research laboratories world-wide.
The wall of carbon nanotubes is made up of one or more layers of carbon atoms forming a hexagonal pattern. The diameter of the tubes can be as small as one nanometre, but their length can reach macroscopic dimensions, a few millimetres or more. Iijima discovered nanotubes in 1991. The most interesting varieties are single-wall nanotubes, which Iijima discovered in 1993 while also developing methods for their production.
Nanotubes have interesting mechanical properties: they are very strong along their axis, and also very flexible. The mechanical, electrical and thermal properties of nanotubes depend on their diameter, as well as on the way the hexagonal surface is rolled up: whether straight, or with a skew that gives it a spiral structure, or helicity. Nanotubes also have very interesting electrical properties: depending on the amount of helicity, the nanotube can be a semiconductor or an excellent conductor.
Many possible applications of nanotubes are now being actively studied and developed. They include nanotube-reinforced materials that are light and strong, such as nanotube-reinforced carbon fibre, already used for specialized applications; nanotube-based electronic components, such as diodes and transistors; transparent and conductive films; electrodes for super-capacitors; field emitters for displays, and many others.
Sumio Iijima is Director of the Research Center for Advanced Carbon Materials, at the National Institute of Advanced Industrial Science and Technology of Tsukuba and Professor at the Department of Materials Science and Engineering at Meijo University, Nagoya.