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The nickel molybdate carbon nanotube composites $({\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}})$ were synthesized by solution blending method. The ${\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}}$ were characterized by scanning electron microscopy (SEM), Raman spectroscopy and UV–Vis absorption spectroscopy. The $({\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}})/\mathrm{\text{PMMA}}$ organic glasses were obtained by dispersing ${\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}}$ in methyl methacrylate (MMA) and polymerizing in a water bath at $75^{\circ }\mathrm{\text{C}}$ for 1h. The nonlinear optical (NLO) properties were measured via $Z$-scan technique. By testing we obtained that $({\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}})/\mathrm{\text{PMMA}}$ has a reverse saturation absorption (RSA) effect and optical limiting (OL) performance. In addition, the RSA effect is enhanced compared to other similar materials. The OL threshold ${(F}_{\mathrm{\text{th}}})$ and the normalized transmittance clamping value $(T_c)$ are calculated and fitted to be ${0.83\mathrm{\text{J}}\mathrm{\text{cm}}}^{-2}$ and ${0.48\mathrm{\text{J}}\mathrm{\text{cm}}}^{-2}$, respectively. Consequently, ${\mathrm{\text{NiMoO}}}_4/\mathrm{\text{CNTs}}$ have significant research value in the direction of extending new materials for laser protection.

This research is concerned with the thermal bending and stability of temperature-dependent nanocomposite curved pipes strengthened with carbon nanotubes (CNTs) subjected to uniform temperature rise. Thermo-mechanical characteristics of the polymer composite pipe are assumed to vary entirely in the thickness by a non-uniform function of the radius. Five different patterns are selected to model the propagation profile of CNTs amongst the pipe thickness. Based on the shear deformation and von-Karman kinematic hypothesis, nonlinear balance equations of the polymer curved pipe are determined via varying the total potential energy of the system. Governing equations as a set of coupled nonlinear differential equations are analytically solved using a perturbation-based technique. Closed-form solutions are derived to estimate large-amplitude deflection of nanocomposite curved pipes with pinned and clamped boundaries under uniform thermal loading. The obtained results show the influences of important parameters such as material/geometrical characteristics and foundation stiffness on the thermally induced nonlinear response of polymer nanocomposite curved pipes.

This paper seeks to study and investigate the wave dispersion behavior in porous functionally graded (FG) carbon nanotube-reinforced composite (CNTRC) beams. The beams comprise four patterns of single-walled carbon nanotubes (SWCNTs) distributed in the polymer matrix. The mixture rule is used to estimate the CNTR beams’ material properties. Innovative to this study are three porosity models describing the porosity distributions within the matrix and a three-unknown integral higher-order shear deformation theory (HSDT) modeling analytically the CNTRC beams with a novel shape function expressing the distributions of shear stresses and strains. The equations of motion for CNTRC beams are derived based on Hamilton’s principle. The stiffness and mass matrices are formulated by a generalized solution of harmonic wave propagation to express the wave dispersion relations. Numerical comparisons with previously published works verify the applicability of this mathematical model. The paper studies the effects of CNTs patterns through the polymer matrix, porosity models, and volume fractions of the porosity and CNTs. Based on the analytical results, augmenting the porosity and CNTs volume fractions leads to faster phase and group velocities. Furthermore, the impact of CNTs volume fractions, porosity models, and porosity volume fractions becomes more pronounced as the wavenumber increases.

The purpose of this research is to study the free vibration response of composite plates made up of three-phase polymer–glass fiber (FG)–carbon nanotubes (CNTs). Polymer matrix has an important property, i.e. the elastic modulus and Poisson’s ratio decrease over time. In this study, the waviness of the CNTs is also taken into consideration. A three-step hierarchical approach is adopted to estimate the elastic properties of the composite media. The governing equations are derived by quasi-3D plate theory and Hamilton’s principle. The adopted quasi-3D model takes into account the nonuniform shear and normal strain distribution and also satisfies the condition of traction-free on top and bottom surfaces. The natural frequencies of this composite are found using the Navier solution method for simply supported boundary conditions. This work investigates how the dimensionless frequency is affected by time, plate geometry, fiber mass fraction, and CNT mass fraction, all of which have a substantial impact. For example, it is highlighted that for a specific plate, after 60s, the frequency drops by about 14% if one takes the time parameter into account. In addition, increasing the mass fraction of CNTs or FGs results in higher frequencies.

The technology progress and increasing high density demand have driven the nonvolatile memory devices into nanometer scale region. There is an urgent need of new materials to address the high programming voltage and current leakage problems in the current flash memory devices. As one of the most important nanomaterials with excellent mechanical and electronic properties, carbon nanotube has been explored for various nonvolatile memory applications. While earlier proposals of "bucky shuttle" memories and nanoelectromechanical memories remain as concepts due to fabrication difficulty, recent studies have experimentally demonstrated various prototypes of nonvolatile memory cells based on nanotube field-effect-transistor and discrete charge storage bits, which include nano-floating gate memory cells using metal nanocrystals, oxide-nitride-oxide memory stack, and more simpler trap-in-oxide memory devices. Despite of the very limited research results, distinct advantages of high charging efficiency at low operation voltage has been demonstrated. Single-electron charging effect has been observed in the nanotube memory device with quantum dot floating gates. The good memory performance even with primitive memory cells is attributed to the excellent electrostatic coupling of the unique one-dimensional nanotube channel with the floating gate and the control gate, which gives extraordinary charge sensibility and high current injection efficiency. Further improvement is expected on the retention time at room temperature and programming speed if the most advanced fabrication technology were used to make the nanotube based memory cells.

We have observed that Terahertz (THz) irradiation to a carbon nanotube quantum dot (CNT-QD) leads to the generation of an excess current in the Coulomb blockade regime. It was found that this THz detected signal survives even when the incident THz wave is extremely weak (~1 fW). This means that the CNT-QD could works as a highly sensitive THz detector.

A photovoltaic photodetector harnessing near infrared band gap absorption by thin films of post-synthetically sorted semiconducting single walled carbon nanotubes (s-SWCNTs) is described. Peak specific detectivity of 6×10¹¹ Jones at -0.1 V bias at 1210 nm is achieved using a heterojunction device architecture: indium tin oxide/ ca. 5 nm s-SWCNT / 120 nm C₆₀ / 10 nm 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) / Ag. The photodiodes are characterized by a series resistance of 2.9 Ω cm² and a rectification ratio of 10⁴ at ±1V. These results are expected to guide the exploration of new classes of solution-processable, mechanically flexible, integrable, thin film photovoltaic photodetectors with tunable sensitivity in the visible and infrared spectra based on semiconducting carbon nanotubes.

A block copolymer/metal-salt solution was used to deposit metal nanoparticles on substrates, from which carbon nanotubes (CNTs) were grown in a chemical vapor deposition (CVD) chamber. Mono and hybrid catalysts of Fe, Ni, and Co-nitrates were tested, and separately Co, Ni, and Cu-chlorides. In both cases cobalt/cobalt-hybrids produced the highest density of multi-wall carbon nanotubes (MWCNTs). Slight vertical growth, though sparse, was observed after growth at 800°C from a nickel catalyst on single-crystal aluminium oxide (~130nm diameter).

The effect of the periodic boundary condition (PBC) on the structure and energetics of nanotubes has been investigated by performing molecular-dynamics computer simulation. Calculations have been realized by using an empirical many-body potential energy function for carbon. A single-wall carbon nanotube has been considered in the simulations. It has been found that the periodic boundary condition has no effect at low temperature (1 K), however, it plays an important role even at intermediate temperature (300 K).

The structural properties of single and multi-wall carbon nanotubes and the formation of carbon nanorods from multi-wall carbon nanotubes have been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that carbon nanorod formation takes place with smallest possible multi-wall nanotubes under heat treatment. On the other hand, it has been also found that single-wall carbon nanotubes are stronger than the multi-wall nanotubes against heat treatment.

The formation of carbon nanorods from various types of carbon nanotubes has been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that carbon nanorod formed from carbon nanotubes with different chirality is not stable even at low temperature.

In this paper we present the results of a dynamical nanotube bending study. Carbon nanotube structures under constant rate bending have been studied using classical molecular dynamics simulations method, with the inter-atomic forces described by Brenner's empirical model potential. We show that the tube diameter and the prevalent temperature play an important role in the outcome. Some of the results have been assessed by letting the most deformed part of the nanotube further relax by using a dynamical tight binding method. Significant difference was found between the empirical and the tight binding models in predicting the structure.

We investigate boron and nitrogen substitutional doping single wall carbon nanotubes (SWCNTs) by first-principles calculations. The optimized geometres of boron and nitrogen substituted SWCNTs exhibit bamboo-like structures. Boron and nitrogen impurities form acceptor and donor states in semiconductor SWCNTs. The highest occupied molecular orbital (HOMO) indicates the trend of forming inter-tube bonds in doping SWCNTs. It may start a new way to form inter-tube bonds by doping in SWCNTs.

We calculate the interaction energy and force between atoms and molecules and single-walled carbon nanotubes described by the Dirac model of graphene. For this purpose the Lifshitz-type formulas adapted for the case of cylindrical geometry with the help of the proximity force approximation are used. The results obtained are compared with those derived from the hydrodymanic model of graphene. Numerical computations are performed for hydrogen atoms and molecules. It is shown that the Dirac model leads to larger values of the van der Waals force than the hydrodynamic model. For a hydrogen molecule the interaction energy and force computed using both models are larger than for a hydrogen atom.

The mechanical properties of single-walled nanotubes (SWNTs) filled with small fullerenes (C20, C36 and C60) were investigated using molecular dynamics (MD) simulation. The interaction between carbon atoms was described by a combination of the many-body Brenner potential with a two-body pair potential. We found that below the critical value of the strain, the stress of SWNT increases linearly with the strain and the Young's modulus of certain SWNT with different filling densities is almost the same for small strain. It was also observed that the buckling force, which corresponds to the critical strain, becomes higher as the filling density of SWNT is increased in general. However, in the case of SWNT of larger radius filled with smaller fullerenes, the dependence of the buckling force on the filling density is expected to be different, which was attributive to the long-distance attractive interaction between atoms of fullerene and those of SWNT.

The fabrication of the carboxyl-modified CNT electrode was described. The electroanalytical investigation of sulfadiazine has been conducted in alkaline aqueous solution at the CNT electrode by voltammetry. Highly reproducible and well-defined cyclic voltammograms were obtained for sulfadiazine with a very good signal to background (S/B) ratio. However, no fouling of the electrode was observed at the CNT electrode within the experimental period of several hours, which illustrated that the CNT electrode was much better than traditional electrodes. Meanwhile, the detection of trace sulfadiazine in milk was also conducted by cyclic voltammetry with satisfactory ratio of recovery, indicating that the nanotube electrode can be used in routine monitoring of sulfadiazine residues in food.

Electrochemical behaviors of dopamine and ascorbic acid have been studied at the carbon nanotube electrode using cyclic voltammetry. Electrocatalysis has been found for dopamine redox reactions at the carbon nanotube electrode in comparison with the glassy carbon electrode. A well-defined oxidative peak for ascorbic acid was observed at the carbon nanotube electrode with the peak potential negative shift versus the glassy carbon electrode. The important discover was that the carbon nanotube electrode can be used to detect low level of dopamine selectively with high sensitivity in the presence of a large excess of ascorbic acid in the acidic media and in the physiological pH buffer solution as well.

The effect of tube geometry on quantum transport in carbon nanotube electron resonators is studied analytically by developing a transfer matrix method. The conductance of metallic chiral nanotubes not only shows oscillating variations as a function of gate voltage with rapid and slow periods, but also exhibits a conductance gap and some resonance conductance peaks in the gap region. These features depend on to a high degree on both tube diameter and chirality and thus provide an experimental means for structure appraisal of the nanotube devices.

A relationship between strain and applied potential is derived for composite films consisting of single-wall carbon nanotubes (SWNTs) and conductive polymers (CPs). When it is derived, an electrochemical ionic approach is utilized to formulate the electromechanical actuation of the film actuator. This relationship can give us a direct understanding of actuation of the nanoactuator. The results show that the well-aligned SWNTs composite actuator can give good actuation responses and high actuating forces available. The actuation is found to be affected by both SWNTs and CPs components and the actuation of SWNTs component has two kinds of influences on that of the CPs component: reinforcement at the positive voltage and abatement at the negative voltage. Optimizations of SWNTs-CPs composite actuator may be achieved by using well-aligned nanotubes as well as choosing suitable electrolyte and an input voltage range.

The electronic structure of the multi-wall carbon nanotubes (MWCN) is studied theoretically by the tight-binding approach. The interwall coupling between layers plays an essential role in the electronic structure. With an increase of the interwall coupling, the energy gap of the semiconducting MWCNs will decrease and eventually vanish, giving rise to the semiconductor–metal quantum phase transition. The metallic layer in the MWCN dominates the electronic structure characteristics near the Fermi level (gapless).