Carbon nanotube localization

The electronic properties of single-walled carbon nanotubes have been studied theoretically using different methods[4-12. It is found that if n — wr is a multiple of 3, the nanotube will be metallic otherwise, it wiU exhibit a semiconducting behavior. Calculations on a 2D array of identical armchair nanotubes with parallel tube axes within the local density approximation framework indicate that a crystal with a hexagonal packing of the tubes is most stable, and that intertubule interactions render the system semiconducting with a zero energy gap[35]. 

The main difference between titania nanotube and the ID nanostructures discussed before is the presence of an hollow structure, but which has significant consequences for their use as catalytic materials (i) in the hollow fiber nanoconfinement effects are possible, which can be relevant for enhancing the catalytic performance (ii) due to the curvature, similarly to multi-wall carbon nanotubes, the inner surface in the nanotube is different from that present on the external surface this effect could be also used to develop new catalysts and (iii) different active components can be localized on the external and internal walls to realize spatially separated (on a nanoscale level) multifunctional catalysts. 

Katsura T, Yamamoto Y, Maehashi K et al (2008) High-performance carbon nanotube field-effect transistors with local electrolyte gates. Jpn J Appl Phys 47 2060-2063... 

Though not strictly functioning as resistors/conductors, carbon nanotubes have just been reported in an extraordinarily vapor-sensitive capacitive device [19]. The electric field lines emanating from the nanotubes are responsible for a localized dielectric response that can be modulated by minute quantities of adsorbate on the nanotube surface. A layer of hydrogen-bonding polymer, or even a mono-layer terminated in mildly acidic groups, increased sensitivity to parts per billion levels. Response strength was correlated with the dipole moment of the analytes. 

To describe the electronic structure of carbon nanotubes the Hubbard model has been chosen as it can describe the electrical and magnetic properties and high temperature superconductivity effects also [11]. The model includes the terms of the electron jump energy in vicinity approach and the energy of Coulomb s repulsion of two electrons localized on the same point of unit cell. Hubbard Hamiltonian for the described system is following [11] ... 

Abstract. In frameworks of semi-empirical PM3-basis equilibrium configurations, total energy, heat of formation, energies of HOMO and LUMO orbitals, density of one-electron states (DOS) of open (12,0) carbon nanotubes with local vacancies and defects are obtained. 

Keywords (6,0) carbon nanotubes, (6,0) C/B/N nanotubes, electrostatic potentials, local ionization... 

Srivastava D, Brenner DW, Schall JD, Ausman KD, Yu M-F, Ruoff RS (1999) Predictions of enhanced chemical reactivity at regions of local conformational strain on carbon nanotubes kinky chemistry. J. Phys. Chem. B 103 4330-4337... 

S. Bose, A.R. Bhattacharyya, R.A. Khare, S.S Kamath, and A.R. Kulkarni, The role of molecular interactions and selective localization of multiwall carbon nanotubes on the electrical conductivity and phase morphology of multicomponent polymer blends (manuscript in preparation). 

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