Direct Force Measurements and Kinking under Elastic Deformation of Individual Multiwalled Boron Nitride Nanotubes

Abstract

Individual multiwalled boron nitride nanotubes of different diameters (40−100 nm) were bent inside a 300 kV high-resolution transmission electron microscope (TEM) using a new fully integrated TEM−atomic force microscope (AFM) piezodriven holder under continuous recording of force−piezodisplacement curves. The tubes were gently compressed in situ (i.e., inside the electron microscope) between a piezomovable aluminum wire and a silicon cantilever. Typically, bending stress values ranging from ∼100 to ∼260 MPa, and corresponding to elastic moduli of 0.5−0.6 TPa, were estimated. Tube gross failures were absent up to very large bending angles (in excess of 115°). Extending the bending angles beyond 30−40°resulted in the elastic deformation of BN nanotubes, which proceeded through the propagation of consecutive momentary kinks. These had the effect of accumulating a bending curvature rather then uniformly curl the tube under the compression load. These kinks were found to be entirely reversible on reloading with no (or marginal) traces of residual plastic deformation.

Large variations in the onset of rippling in concentric nanotubes

“…3,4 During bending the tubes can however deform in buckling or rippling patterns, much like macroscopic tubes do, and the bending stiffness will drop significantly. Such deformations have been observed for nanotubes made of C, 5,6 BN, 7,8 and WS 2 , 9 while similar deformations are also expected to occur in MoS 2 .…”

In situ TEM measurements of the mechanical properties and behavior of WS2 nanotubes

“…Moreover, long and slender multiwalled carbon nanotubes which are under compression strain, behave as elastica rods and form bends and loops [2]. Kink formation was also observed for BN nanotubes [26]. In situ TEM bending of BN nanotubes to angles beyond 30°40° resulted in elastic deformation which proceeded through the propagation of consecutive momentary kinks.…”

EXPERIMENTAL NANOMECHANICS OF ONE-DIMENSIONAL NANOMATERIALS BY IN SITU MICROSCOPY

“…13 A TEM equipped with a pizeodriven stage allows manipulating the specimen at nanometer scale. [46][47][48][49][50][51][52][53][54] Figure 18 is a schematic illustration of a TEM-SPM hybrid system in which a nanotube can be welded at the two ends of the two facing tips, 51 one is STM tip and the opposite side Au/Pt tip. Two ends or four ends electric feed through can be designed and carried out for the electrical conductance measurements.…”

“…Several successful examples were demonstrated for carbon nanotubes and BN tubes. 48,51,52 A typical example is shown in Fig. 20 for the pizeo-electric effect of BN tubes by bending the BN tubes using the TEM-SPM method in a TEM chamber.…”

“…21 which used the commercialized Nanofactory Instruments AB TM TEM-AFM hybrid specimen holder. 48 A silicon cantilever is attached to a fixed MEMS force sensor. An aluminum wire (for a subsequent calibration) with a mounted NW/NT sample was placed on the movable pizeo-driven side of the holder.…”