Deformation Behavior And Structure Evolution Of Nanotube Filled With Metal Nanowire

Nanotube composite materials are one-dimensional nano-material, which are obtained by filling nanoparticles and nanowires into the cavity of nanotubes. In recent years, they have attracted much attention and have a broad application prospects due to their unique properties at mechanical and electrical realm. Up to now, many elements have been successfully filled into the nanotubes, for example fullerenes, metals,water molecular and many kinds of compounds. With the hollow tubes, the filled tubes generally present the high axial strength and Young’s modulus. Nanotubes filled with metal particals provide possibilities for application of many kinds of nano-devices, magnetic waves absorption, high density magnetic data storage and sensor. So the change of mechanical properties is the hot research topic in these research fileds.We have employed molecular dynamics to study the deformation of copper-filled single-walled boron-nitride nanotubes (Cu@BNNTs) under axial compression, the stretching nanomechanics of single-walled carbon nanotubes filled with nickel atoms (Ni@CNTs), the vibration between graphene and gold-filled single-walled boron-nitride nanotubes (Au@BNNTs). In the simulations, the compression process use universal force to describe the atomic interactions. The carbon-carbon interaction is described by REBO potential, the carbon-metal interaction by Lennard-Jones potential and the metal-metal interaction by tight-binding potential.We employ molecular mechanics simulation to study the buckling behavior and mechanical properties of Cu@BNNTs. The strain energy of Cu@BNNT gets higher with the increase of the diameter, especially in larger compressive displacement. With regard to the stability, it gets better with smaller diameter, which is affected by the distribution of filling particles. Comparison of the buckling behavior of the Cu@BNNT(7,7) and Cu@BNNT(11,11) and analysis of the energy reveals that the buckling Cu@BNNT(7,7) has two mutually perpendicular invaginations, whereas the buckling Cu@BNNT(11,11) has only one central dilatation, which indicates Cu@BNNT with big diameter has larger compressive resistance and a small energy loss. Different structures show different buckling modes, which is caused by the density distribution of Cu atoms filled into BNNTs. The stability of a BNNT filled with Cu nanowire gets higher with the increase of the Cu atomic number.The stretching mechanism and mechanical properties of Ni@CNTs are studied via molecular dynamics simulations. During the stretching course, the CNTs are gradually elongated along the axial direction, tapering gradually into a long tail-like tip. And the bond length and bond angle are both changed. We can see from the pair correlation function that the value of the first peak gradually falls off and the value of the second peak gradually increases, indicating that the distance between two adjacent atoms gets larger with the stretching strain. We have found the strain energy increases linearly with the stretching strain. After it reaches the highest point, the curve drops abruptly, indicating the structure has buckled, which can be clearly reflected by the distribution of the strain energy. The stretching, behavior of nickel nanowires filled into different kind of canbon nanotubes is also investigated. Both the two composites are not sensitive with the tube diameter. Young’s modulus of the two composites decreases as the diameter increases, and the zigzag CNTs is not the case.The interaction between Au@CNT and graphene is investigated. We have found the graphene spontaneously self-scrolls onto Au@CNT and forms a more stable coreshelled composite nanostructure. The decrease of the potential energy suggests that the self-assembly is a spontaneous phenomenon and the system is increasingly stable during this process. The vander Waals interaction between graphene and Au@CNT is the driving force to drive the self-scrolling. The interaction between Au@BNNT and graphene is also studied. We have found that the tube and graphene is vibrating violently, and the gold atoms continuous flow from the tube. The tracks of gold atoms inside the tube are along the shape of nanowires, which can be clearly seen from the mean square displacements as the function of time. And the flow of the atoms is not merely due to the vibration of the tube, but also the collisions of atoms. The position of Au@BNNT on the graphene and the length of Au@BNNT can both affect the flow time of the gold atoms. The overflow number and rate of Au atoms as a function of time are mapped when the Au@BNNT interacts with the single layer graphene and bilayer graphene. When we fill the water molecule into the BNNT and put the composite on the graphene, the water molecule also flow from the tube.These researche results above have made us understand the mechanical deformation mechanism and structure evolution of metal-filled nanotubes. These can be a guideline for the manufacture of miniaturized components and enhanced nano-composites. And we hope to find nano-devices with excellent properties in this way, such as oscillator and nanopump.