Search results for "CNT"

DFT studies on armchair (5, 5) SWCNT functionalization. Modification of selected structural and spectroscopic parameters upon two-atom molecule attac…

2015

Abstract Density functional theory (DFT) studies on adsorption of several gaseous homo- and hetero-diatomic molecules (AB) including H2, O2, N2, NO and CO on external surface of H-capped pristine armchair (5, 5) single-walled carbon nanotube (SWCNT) were conducted. Structures of C70H10 and the corresponding C70H10–AB adducts were fully optimized at the B3LYP/6-311G* level of theory. Calculated HOMO/LUMO energy gaps (Eg), 13C NMR chemical shifts and IR/Raman parameters were analyzed and critically compared with available experimental data. Significant changes of carbon NMR atom chemical shifts (up to −100 ppm) and shielding anisotropies (up to −180 ppm) at sites of addition were observed. Fu…

Morphology and properties of polyamide/CNTs nanocomposite fibres

2010

Hydrogen activation on N‐doped carbon networks

2014

Tensile Strength of CNT Fibres: Characteristic Length, Stress Transfer and other Impact Factors

2014

The initial strength hype over carbon nanotubes arose from predictions of the strength of individual graphene layers, encouraged by measurements of individual MWCNTs and SWCNT bundles in AFM [1, 2]. However, while the scientists were professionally explicit as to what they had measured, the publicity assumed that these figures could also be readily realized in materials made from these components. It’s against a background of this overselling that we examine the gradual improvement in strength of macroscopically useful materials. Yarn-like fibres composed of carbon nanotubes made by the direct spinning process [3] have been used as the subject of this study. There have been occasional obser…

High-Yield of Memory Elements from Carbon Nanotube Field-Effect Transistors with Atomic Layer Deposited Gate Dielectric

2008

Carbon nanotube field-effect transistors (CNT FETs) have been proposed as possible building blocks for future nano-electronics. But a challenge with CNT FETs is that they appear to randomly display varying amounts of hysteresis in their transfer characteristics. The hysteresis is often attributed to charge trapping in the dielectric layer between the nanotube and the gate. This study includes 94 CNT FET samples, providing an unprecedented basis for statistics on the hysteresis seen in five different CNT-gate configurations. We find that the memory effect can be controlled by carefully designing the gate dielectric in nm-thin layers. By using atomic layer depositions (ALD) of HfO$_{2}$ and T…

OH-functionalized open-ended armchair single-wall carbon nanotubes (SWCNT) studied by density functional theory

2011

The structures of ideal armchair (5,5) single-wall carbon nanotubes (SWCNTs) of different lengths (3.7, 8.8, and 16.0 A for C40H20, C80H20, and C140H20) and with 1–10 hydroxyl groups at the end of the nanotube were fully optimized at the B3LYP/3-21G level, and in some cases at the B3LYP/6-31G* level, and the energy associated with the attachment of the OH substituent was determined. The OH-group attachment energy was compared with the OH functionalization of phenanthrene and picene models and with previous results for zigzag (9.0) SWCNT systems. In comparison to zigzag SWCNTs, the armchair form is more (by about 5 to 10 kcal mol−1) reactive toward hydroxylation. Figure The structures of ide…

Quantum Transport and Current Distribution at Radio Frequency in Multiwall Carbon Nanotubes

2012

Multiwall carbon nanotubes represent a low-dimensional material that could serve as building blocks for future carbon-based nanoelectronics. The understanding of the electromagnetic performances at radio frequency of these materials for use in nanointerconnects is strictly related to the analysis of their transport properties as function of the working conditions. In this paper, we present an explicit expression of the conducting channels as function of diameter, temperature, doping, and supply voltage for both metallic and semiconducting carbon nanotubes. The proposed formula is based on the Dirac cone approximation of the conducting band energy of graphene nearby the Fermi points, combine…

Carbon nanotubes thin filters for x-ray detectors in space

2022

In this paper, we present the first results from an investigation performed on nanometric thin pellicles based on carbon nanotubes (CNT) of potential interest for manufacturing large area optical blocking filters to protect soft X-ray detectors in astrophysics space missions. In order to evaluate the effective capability of such materials to block UV/VIS/IR radiation, while being highly transparent in the soft X-rays and strong enough to withstand the severe launch stresses, we have performed a suite of characterization measurements. These include: UV/VIS/IR and X-ray absorption spectroscopy, X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy on bare and Al coated small self-…

Carte marine e rischi geologici

2008

The investigations carried out by the "Gruppo di Geologia Marina" of the Palermo University in the framework of the CARG project, have been focused on the marine sectors between the Egadi Islands offshore and the Cefalù Basin (NW Sicilian offshore). The research activities have yielded new results on the following fields: (i) sedimentation and coastal dynamics, (ii) sea bottom cartography and mapping of submerged structures, (iii) morpho-bathymetry and geological risk assessment

Characterization of the dispersion of carbon nanotubes in nanocomposites by means of a non-destructive evaluation technique

An extensive use of CNTs enhanced polymer composites can be boosted by novel NDE techniques able to check the quality of the products made of these nanocomposites in order to guarantee that their specifications are met. It is well known in literature that the parameter that much more than others can affect the enhancing capabilities of the added nanoparticles is their dispersion. All the resulting physical properties of the CNTs based polymer composites depend strongly on level of dispersion of the CNTs throughout the matrix. Here we presented a novel NDE technique based on infrared thermography able to test the dispersion of the added nanoparticles in nanocomposites. Two different procedur…