Charged Carbon Nanotube Structure And Mechanical Properties

Carbon nanotubes(CNTs) are widely studied because of its unusual structure, electronic properties and mechanical properties, since the discovery in 1991. In recent years, with CNTs and nano-materials research, CNTs will have vast and promising prospect of application.In this paper, we investigated the structural changes of charged carbon nanotubes and related mechanical properties by first-principles calculation method. The results show the shape of (4,2), (3,3) and (5,0) CNTs would be changed with a certain amount of charge. The length of CNTs become longer and the diameter of CNTs become larger. The port of CNTs is like a trumpet. Part of the C-C bond will be broken. Carbon atoms fly CNTs out. Different types of charged atoms of CNTs departed the port in different ways. (4,2) CNT carbon most likely to happen Coulomb explosion, followed by the (5,0) carbon tube, and finally (3,3) carbon tube. After coulomb explosion, (3,3) and (5,0) CNTs nearly left no charge, closed to the neutral CNTs. But (4,2) CNT still has a little of charge. Variable-length carbon-carbon caused bond length of CNTsare most obviously (5,0) carbon tube, followed by (3,3) CNT, and finally (4,2) CNT, namely (5,0) CNT most likely to get longer. However the change of three types of CNTs diameter is opposite. Neutral CNTs taken a small amount of negative charge have the lower energy, the structure is more stable. It shows that C-C bond of CNTs is not saturated with a certain degree of electronegativity. The curve of total bonding energy is a parabolic curve. Charges are mostly concentrated in the port of CNTs, and extra charges have an obviously effect to the port of CNTs. The criterion of (6,6) CNT happen coulomb explosion is the 1 position in the C-C bond length variable longer, while 2 position C-C bond length from long to shorter. Line and plane angle A of charged (6,6) CNT is greater than the line plane angle B of charged (8,0) CNT. The port of charged (6,6) CNT expand more apparent than the port of charged (8,0) CNT. Additional charges will affect the elastic modulus of CNTs. With a little of charge, the energy of (6,6) and (8,0) CNTs will decrease. The elastic modulus will increase monotonically. A little charge of CNTs is expanded more difficult than neutral CNTs. When the two CNTs with a certain amount of charge, additional charge repulsion between carbon atoms makes more than gravity, C-C bond is weakened. The elastic modulus decreases monotonically again, and charged CNTs is easy to expand. Elastic modulus of CNTs relate to the change of CNTs energy and the deformation of CNTs. Charge a certain amount of carbon nanotubes will take place on the strong Coulomb repulsion,σbond is weakened, the elastic modulus is also reduced.