Revealing the Anomalous Tensile Properties of WS₂ Nanotubes by in Situ Transmission Electron Microscopy

Abstract

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 "defect-free" structures studied previously. In addition, the fracture strength of the "thick" 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.

Dislocation motion and grain boundary migration in two-dimensional tungsten disulphide

“…They can act as nucleation sites for the onset of deformation, when subjected to stress [2][3][4] . When exposed to chemical functional groups, defects can also behave as highly reactive sites and efficiently trap different molecules 5,6 .…”

Nanomechanical cleavage of molybdenum disulphide atomic layers

“…In this work, we design an in situ transmission electron microscopy (TEM) probing technique [17][18][19][20] to investigate the initial stages of the 2D crystal cleavage, which is defined here as the 'nanomechanical cleavage', using MoS 2 atomic layers as a model material. By precisely manipulating an ultra-sharp metal probe to contact the pre-existing crystalline steps of the MoS 2 single crystals, atomically thin flakes are delicately peeled off, selectively ranging from a single, double to more than 20 atomic layers.…”

Atomic force microscopy indentation to determine mechanical property for polystyrene–silica core–shell hybrid particles with controlled shell thickness

“…The applications of nontraditional abrasives in CMP technology require direct insight into the particles' mechanical properties, such as elastic modulus (E), Poisson ratio (ν), hardness (H), interfacial adhesion and friction, as well as their size-dependent effects [4]. In order to acquire quantitatively this information, different measurement methods have been developed, mainly including nano-indentation with an atomic force microscope (AFM) [19,20], in-situ compression, bend and tension [21,22] by a transmission electron microscope-scanning probe microscope (TEM-SPM) platform. So far, in-situ high resolution TEM is considered as the most advanced instrument to accurately measure the mechanical properties of micro/nano-scaled samples.…”

“…The dislocation nucleation from a free surface and plastic deformation between the SPM probe and the sample contact surface were observed in-situ. Moreover, Tang et al [22] analyzed the tensile properties of multiwalled WS 2 nanotubes under uniaxial tension using in-situ TEM tests. It was found that the thick WS 2 nano-tubes could sustain a much higher tensile force than "defect-free" thin nano-tubes.…”