In Situ Resistance Measurements of Strained Carbon Nanotubes

A (10x10) single-walled carbon nanotube consisting of 400 atoms with 20 layers is simulated under tensile loading using our developed O(N) parallel tight-binding molecular-dynamics algorithms. It is observed that the simulated carbon nanotube is able to carry the strain up to 122% of the relaxed tube length in elongation and up to 93% for compression. Young s modulus, tensile strength, and the Poisson ratio are calculated and the values found are 0.311 TPa, 4.92 GPa, and 0.28...

The fracture of carbon nanotubes is studied by atomistic simulations. The fracture behavior is found to be almost independent of the separation energy and to depend primarily on the inflection point in the interatomic potential. The rangle of fracture strians compares well with experimental results, but predicted range of fracture stresses is marketly higher than observed. Various plausible small-scale defects do not suffice to bring the failure stresses into agreement with a...

We report a method for probing electromechanical properties of multiwalled carbon nanotubes(CNTs). This method is based on AFM measurements on a doubly clamped suspended CNT electrostatically deflected by a gate electrode. We measure the maximum deflection as a function of the applied gate voltage. Data from different CNTs scale into an universal curve within the experimental accuracy, in agreement with a continuum model prediction. This method and the general validity of the...

We study the physics of adhesion and the contact mechanics at the nanoscale with a peeling experiment of a carbon nanotube on a flat substrate. Using an interferometric atomic force microscope and an extended force modulation protocol, we investigate the frequency response of the stiffness of the nano-contact from DC to 20 kHz. We show that this dynamic stiffness is only weakly frequency dependent, increasing by a factor 2 when the frequency grows by 3 orders of magnitude. Su...

Energetically the single sheet of graphite (graphene) is more stable than the nanotube. The energy difference between the two systems can be directly related to the strain energy involved in rolling up the graphene sheet to form the nanotube. We have carried out first principle electronic structure calculations and evaluated the strain energy as a function of the nanotube radius. The dependence of the strain energy on the diameter of the nanotube has been found by several gro...

We combine electromechanical measurements with {\em ab initio} density functional calculations to settle the controversy about the origin of torsion-induced conductance oscillations in multi-wall carbon nanotubes. According to our observations, the oscillation period is inversely proportional to the squared diameter of the nanotube, as expected for a single-wall nanotube of the same diameter. This is supported by our theoretical finding that differential torsion effectively d...

Actuators at the nanoscale are assuming great important in todays shrinking electronics industry where a system-on-chip approach is used to integrate multi-functional systems and devices. Integration of sensors, actuators, information processing, and storage have become extremely important, more so at the sub-micrometer scale. Here we utilized vertically aligned carbon nanotube forests bonded onto a piezoelectric substrate to provide sensing of nanoscale forces and actuation ...

We discuss the local cutting of single-walled carbon nanotubes by a voltage pulse to the tip of a scanning tunneling microscope. The tip voltage ($\mid V \mid \ge $~3.8 eV) is the key physical quantity in the cutting process. After reviewing several possible physical mechanisms we conclude that the cutting process relies on the weakening of the carbon-carbon bonds through a combination of localized particle-hole excitations induced by inelastically tunneling electrons and ela...

Using an atomic force microscope we have created nanotube junctions such as buckles and crossings within individual single-wall metallic carbon nanotubes connected to metallic electrodes. The electronic transport properties of these manipulated structures show that they form electronic tunnel junctions. The conductance shows power-law behavior as a function of bias voltage and temperature, which can be well modeled by a Luttinger liquid model for tunneling between two nanotub...

Sensing technologies have been under research and development for their varied applications from microelectronics to space exploration. With the end of Moores law in sight, there is growing demand for shrinking materials and improving sensitivity and range of sensing of sensors. Carbon nanotubes (CNTs) offer an excellent combination of small size (in the order of nanometers in two dimensions and micrometers in the third dimension), varied current conductivity (from insulating...