Definition of carbon nanotubes
Carbon nanotubes are one-dimensional quantum materials with special structures (radial dimensions are on the order of nanometers, axial dimensions are on the order of micrometers, and the ends of the tube are basically sealed). Carbon nanotubes are mainly coaxial tubes composed of carbon atoms arranged in hexagons, ranging from several layers to tens of layers. A fixed distance is maintained between the layers, about 0.34 nm, and the diameter is generally 2-20 nm. And according to the different orientation of the carbon hexagon in the axial direction, it can be divided into three types: zigzag, armchair and spiral. The spiral carbon nanotubes have chirality, while the zigzag and armchair carbon nanotubes have no chirality.