Carbon nanotube

 Carbon nanotubes, also known as buckytubes, are one-dimensional quantum materials with a special structure (the radial size is in the order of nanometers, the axial size is in the order of micrometers, and the two ends of the tube are basically sealed). Carbon nanotubes are mainly composed of carbon atoms arranged in hexagons to form a coaxial tube with several to dozens of layers. A fixed distance between the layers is maintained, about 0.34nm, and the diameter is generally 2~20 nm. According to the different orientations of the carbon hexagon along the axis, it can be divided into three kinds: sawtooth, armchair and spiral. The spiral carbon nanotubes are chiral, while the serrated and armchair carbon nanotubes are not.