Jian Ping Lu

Elastic Properties of Carbon Nanotubes and Nanoropes

Elastic properties of carbon nanotubes and nanoropes are investigated using an empirical force-constant model. For single and multiwall nanotubes the elastic moduli are shown to be insensitive to structural details such as the helicity, the radius, and the number of walls. The tensile Young{close_quote}s modulus and the torsion shear modulus of tubes are comparable to that of the diamond, while the bulk modulus is smaller. Nanoropes composed of single wall nanotubes have the ideal elastic properties of high tensile stiffness and light weight. {copyright} {ital 1997} {ital The American Physical Society}

Gas molecule adsorption in carbon nanotubes and nanotube bundles

We studied various gas molecules (NO2, O2, NH3, N2, CO2, CH4, H2O, H2, Ar) on single-walled carbon nanotubes (SWNTs) and bundles using first principles methods. The equilibrium position, adsorption energy, charge transfer, and electronic band structures are obtained for different kinds of SWNTs. Most molecules adsorb weakly on SWNTs and can be either charge donors or acceptors to the nanotubes. We find that the gas adsorption on the bundle interstitial and groove sites is stronger than that on individual nanotubes. The electronic properties of SWNTs are sensitive to the adsorption of certain gases such as NO2 and O2. Charge transfer and gas-induced charge fluctuation might significantly affect the transport properties of SWNTs. Our theoretical results are consistent with recent experiments.

Generation of continuous and pulsed diagnostic imaging x-ray radiation using a carbon-nanotube-based field-emission cathode

X-ray radiation is widely used in medical and industrial applications. The basic design of the x-ray tube has not changed significantly in the last century. In this paper, we demonstrate that medical diagnostic x-ray radiation can be generated using a carbon nanotube (CNT)-based field-emission cathode. The device can readily produce both continuous and pulsed x-rays with a programmable wave form and repetition rate. A total emission current of 28 mA was obtained from a 0.2 cm2 area CNT cathode. The x-ray intensity is sufficient to image a human extremity at 14 kVp and 180 mAs. Pulsed x-ray with a repetition rate greater than 100 kHz was readily achieved by programming the gate voltage. The CNT-based cold-cathode x-ray technology can potentially lead to portable and miniature x-ray sources for industrial and medical applications.

Band-gap change of carbon nanotubes: Effect of small uniaxial and torsional strain

We use a simple picture based on the

Novel magnetic properties of carbon nanotubes.

\ensuremath{\pi}

First-Principles Study of Li-Intercalated Carbon Nanotube Ropes

electron approximation to study the band-gap variation of carbon nanotubes with uniaxial and torsional strain. We find (i) that the magnitude of slope of band gap versus strain has an almost universal behavior that depends on the chiral angle, (ii) that the sign of slope depends on the value of

Noncovalent functionalization of carbon nanotubes by aromatic organic molecules

(n\ensuremath{-}m)\mathrm{mod}3,

Work functions of pristine and alkali-metal intercalated carbon nanotubes and bundles

and (iii) a novel change in sign of the slope of band gap versus uniaxial strain arising from a change in the value of the quantum number corresponding to the minimum band gap. Four orbital calculations are also presented to show that the

Contact resistance between carbon nanotubes

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Atomic Scale Sliding and Rolling of Carbon Nanotubes

orbital results are valid.