Reduction of the buckling strength of carbon nanotubes resulting from encapsulation of C_(60) fullerenes

摘要

The effect of encapsulation of C_(60) fullerenes upon the buckling strength of hosting carbon nanotubes (CNTs) has been investigated, using molecular dynamics (MD) simulations. The simulation results show that encapsulating C_(60) fullerenes into some CNTs with diameters larger than that of the (10, 10) CNT, in particular the (14, 14) and (18, 18) CNTs, significantly reduces the buckling strength, in contrast to the conventional wisdom that fillings increase the mechanical strength of hollow structures. The simulations have also confirmed the previous findings that filling a (10, 10) CNT with C_(60) increases the buckling strength. Our detailed analysis reveals that the interaction between the C_(60) fullerenes and the hosting (10, 10) CNT is cylindrically symmetric, while the presence of a zigzag array of C_(60) inside the (14, 14) CNT breaks the cylindrical symmetry and so does the presence of the three arrays of C_(60) inside the (18,18) CNT. The induced asymmetries cause one peak for the C_(60)@(14, 14) system and three peaks for the C_(60)@(18, 18) system in the corresponding force distribution along the circumferential direction. The force concentration leads to observed reduction in the buckling strength. The reduction is more severe for C_(60)@(14, 14) than for C_(60)@(18, 18), because the force distribution of the former system is more asymmetric.