Carbon Nanotubes

摘要

The discovery more than two decades ago of the allotrope of carbon referred to as buckminsterfullerene (more commonly called fullerene or C_(60)) was a seminal event in the genesis of nanotechnology. This key discovery1 showed how intense energy sources may be used to vaporize ordinary carbon and convert it into nanomaterials such as fullerenes and carbon nanotubes. Of the carbon nanotubes, the multiwalled variant was synthesized initially in 1991,2 although it is now evident that the simultaneous discovery of single-walled nanotubes at NEC3 and IBM4 in 1993 was even more revolutionary from a materials science/physics/chemistry viewpoint. This article focuses on properties of the single-walled form of carbon nanotubes, hereafter referred to as SWNTs. SWNTs are unique materials for several reasons: they are prototypical quasi one-dimensional quantum wires composed of a single element (carbon), with walls only one atom thick and tens of atoms in circumference. Every carbon atom lies on the surface of the nanotube and forms part of a strong covalently bonded structure. SWNTs are typically about 1 nm in diameter but have lengths from hundreds of nanometers to several centimeters, with long-range crystalline periodicity retained along the tube axis. Studies indicate that SWNTs possess remarkable mechanical properties, including an elastic modulus near 1000 GPa and tensile strength of several tens of gigapascals, that are comparable to those predicted for single sheets of graphite.