文摘
Mechanical properties and fracture behaviors of multiwalled WS2 nanotubes produced by large scale fluidized bed method were investigated under uniaxial tension using in situ transmission electron microscopy probing; these were directly correlated to the nanotube atomic structures. The tubes with the average outer diameter 40 nm sustained tensile force of 2949 nN and revealed fracture strength of 11.8 GPa. Surprisingly, these rather thick WS2 nanotubes could bear much higher loadings than the thin WS2 nanotubes with almost 鈥渄efect-free鈥?structures studied previously. In addition, the fracture strength of the 鈥渢hick鈥?nanotubes did not show common size dependent degradation when the tube diameters increased from 20 to 60 nm. HRTEM characterizations and real time observations revealed that the anomalous tensile properties are related to the intershell cross-linking and geometric constraints from the inverted cone-shaped tube cap structures, which resulted in the multishell loading and fracturing.
Keywords:
WS2 nanotubes; mechanical properties; tensile; defect; cross-linking; in situ microscopy