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A supercell of a nanotube heterojunction formed by an (8, 0) carbon nanotube (CNT) and an (8, 0) silicon carbide nanotube (SiCNT) is established, in which 96 C atoms and 32 Si atoms are included. The geometry optimization and the electronic property of the heterojunction are implemented through the first-principles calculation based on the density functional theory (DFT). The results indicate that the structural rearrangement takes place mainly on the interface and the energy gap of the heterojunction is 0.31 eV, which is narrower than those of the isolated CNT and the isolated SiCNT. By using the average bond energy method, the valence band offset and the conduction band offset are obtained as 0.71 and −0.03 eV, respectively.

Under the framework of Maxwell–Garnett (M-G) model, the optical and electrical properties of single-walled carbon naotube (SWCNT), double-walled carbon nanotube (DWCNT) and hydrogen-doped carbon nanotube (H-doped CNT) in terahertz (THz) region have been investigated. It has been found that as frequency increases the loss tangent and conductivity show a peak. The loss tangent and conductivity of SWCNT is larger than that of DWCNT and H-doped CNT. The loss tangent and conductivity increase with the increases of filling factor and the decreases of geometrical factor.

Adsorption of hydrogen molecules on an Ni-doped (8,0) single-walled carbon nanotube (SWNT) is investigated by using first-principles density functional calculations. The result shows that a single Ni atom adsorbed on the bridge site of the tube could cannot dissociate the H2, however it can chemisorb three H2 at most, with the average binding energy per H2 suitable for the hydrogen storage at the room temperature. More H2 would physisorb around an Ni atom weakly. As for the SWNT with an Ni dimer adsorbed, we find that when the H2 approaches the Ni–Ni bond, it dissociates without overcoming any barrier and makes bonds with Ni atom.

We theoretically study the electron transport properties for two coupled single-walled carbon nanotube quantum dots connected to metallic electrodes under the irradiation of an external electromagnetic field at low temperatures. Using the standard nonequilibrium Green's function techniques, we examine the time-averaged transmission coefficient and linear conductance. It is shown that by some numerical examples, the photon-assisted inter-dot coupling causes Fano resonance and the conductance of the system is sensitive to the external field parameters. The transport dependence on the external field parameters may be used to detect the high-frequency microwave irradiation.

Effects of local low-energy irradiation on the electric properties of metallic single-walled carbon nanotubes were studied. Defects formed by 20 keV-electron irradiation in an electron beam lithography system converted the room-temperature electric properties to p-type or ambipolar semiconducting. Coulomb oscillation was also observed at room temperature. The results also suggest that electric measurements are inconclusive for distinguishing whether a nanotube is metallic or semiconducting.

Spin-filter effect is predicted in a weak coupled junction composed of a nonmagnetic metal electrode and a zigzag carbon nanotube. This effect is induced by the magnetic edge states of the nanotube, and can produce spin-polarized current in the absence of an external magnetic field. We find that the spin polarization of the current changes its sign at the half-filling point of the nanotube, thus electric field control of spin transport can be realized. Furthermore, we find the coupling strength of the junction may cause a magnetic transition on the edge of the nanotube.

The synthesis of vertically aligned single-walled carbon nanotube (SWCNT), double-walled carbon nanotube (DWCNT), and triple-walled carbon nanotube (TWCNT) films has been achieved by a combination of radiation-heated chemical vapor deposition (RHCVD) and long-throw sputtering. The proportions of specific walled CNTs/as-grown CNTs are as follows: SWCNT/CNT ratio of 87%, DWCNT/CNT ratio of 83%, and TWCNT/CNT ratio of 62%. When the population density of vertically aligned CNTs on a substrate ranges from 1.1 ×109 to 7.1 ×1010 bundles/cm2, the selective growth of graphene walls of CNTs is achieved. As outer diameters and the number of graphene walls of CNTs increase, CNTs grow longer. It is considered that the larger the metallic catalyst diameter, the longer the catalyst lifetime.

A method is demonstrated for constructing models on which we show that carbon nanotubes with optional type and diameter can be connected to different three-dimensional surfaces. Basic examples (zigzag and armchair-type junctions and holes) are studied in this paper.

We have investigated the mechanical vibrations of nanotube cantilevers in terms of energy loss. The quality factors, Q, for the resonant vibrations of nanotubes synthesized by arc discharge and chemical vapor deposition are related to Young's modulus and diameters, which correspond to the defect density and the number of van der Waals (vdW) interlayer interactions. Molecular dynamics simulations reveal that pinhole defects on the wall of a nanotube significantly degrade the Q factor, whereas the strength in a small strain region remains high, which is similar to the case of a perfect nanotube. Furthermore, the Q factor is affected by the presence of the vdW interlayer interactions.

We investigated single-walled carbon nanotube (SWNT) growth on electrochemically etched W tips by Co/Al catalyst-assisted chemical vapor deposition using ethanol as the carbon source. Vertically aligned SWNTs on the W tip apex were obtained by applying a voltage of 50 V to the W tip during the chemical vapor deposition. Also, we examined the field emission property of the vertically aligned single-walled carbon nanotube tip, and showed that it exhibits a low threshold voltage for electron emission. This growth method is useful for investigating the emission properties of individual SWNTs.

High intensity electron emission cathodes based on carbon nanotube films have been successfully fabricated. An investigation of the explosive field emission properties of the carbon nanotube cathode in a double-pulse mode was presented and a high emission current density of 245 A cm−2 was obtained. The formation of the cathode plasma layer was proved and the production process of the electron beams from the cathode was explained. The time and space resolution of the electron beams flow from the cathode was investigated. The plasma expanded at a velocity of ~8.17 cm µs−1 towards the anode and influenced on the intensity and distribution of electron beams obviously. The formation of cathode plasma had no preferential position and the local enhancement of electron beams was random. This carbon nanotube cathode appears to be suitable for high-power microwave device applications.

The stimulation of carbon nanotubes (CNT) growth in a thermal CVD process using an acetylene/nitrogen gas mixture by KrF-excimer laser exposure of iron nitrate coated silicon is described. At moderate laser fluences of ~1 J/cm2 the growth of nanotube bundles up to 100 μm consisting of vertical aligned multi-walled carbon nanotubes (VA-MWCNT) is observed. AFM measurements show the formation of nanoparticles in the laser-exposed areas. At this catalytic sites the nanotubes grow and sustain one another and forming the well-defined bundles. Via the laser exposure the control of the catalytic sites formation and consequently the nanotube growth and properties can be achieved.

We have investigated the interaction between an Fe atom and a single-walled carbon nanotube near the entrance, by means of the first principles total energy calculation. (10, 0) carbon nanotube composed of 80 atoms is used for the calculation. We determined the most stable position of the Fe atom near the entrance of the nanotube.

In this paper we present some simulation results about the behaviour of water molecules inside a single wall carbon nanotube (SWNT). We find that the confinement of water in an SWNT can induce a wave-like pattern distribution along the channel axis, similar phenomena are also observed in biological water channels. Carbon nanotubes(CNTs) can serve as simple nonpolar water channels. Molecular transport through narrow CNTs is highly collective because of tight hydrogen bonds in the protective environment of the pore. The hydrogen bond net is important for proton and other signal transports. The average dipoles of water molecules inside CNTs (7,7), (8,8) and (9,9) are discussed in detail. Simulation results indicate that the states of dipole are affected by the diameter of SWNT. The number of hydrogen bonds, the water–water interaction and water–CNT interaction are also studied in this paper.

We present experimental evidence of in situ fabrication of multi-walled carbon nanotube junctions via electron beam induced deposition. The tip-to-tip interconnection of the nanotubes involves the alignment of two nanotubes via a piezodriven nanomanipulator and nano-welding by electron beam deposition. Hydrocarbon contamination from the pump oil vapour of the vacuum system of the TEM chamber was used as the solder; this is superior to the already available metallic solders because its composition is identical to the carbon nanotube. The hydrocarbon deposition, with perfect wettability, on the nanotubes establishes strong mechanical binding between the two nanotubes to form an integrated structure. Consequently, the nanotubes cross-linked by the hydrocarbon solder produce good electrical and mechanical connections. The joint dimension was determined by the size of the electron beam, which results in a sound junction with well-defined geometry and the smallest junction size obtained so far. In situ electric measurement showed a linear current-voltage property for the multi-walled nanotube junction.

We have developed a fast and facile CO2 laser assisted chemical vapour deposition LA-CVD synthesis route for carbon nanotubes, which requires no supplementary hydrocarbon feedstock. The technique yields a broad range of carbon nanostructures due to the sharp thermal gradient afforded by the laser. This in turn provides useful information on the changes in nanostructure formation with temperature. A distinct and unusual aspect of this route is that, unlike other synthesis approaches, the obtained single wall carbon nanotube diameters show no dependence on the synthesis parameters and this is attributed to their nucleation via fullerenes and fullerene caps. The results suggest fullerene nucleation may also be active in other CVD synthesis routes.

In this overview paper, we present low-temperature electronic transport measurements of carbon nanotube quantum dots with a back gate. In a semiconducting tube, charge carriers could be completely depleted. The addition energy and the excitation spectrum have been studied as a function of the number of charges (electrons or holes), one by one. We observe electron–hole symmetry, which is a direct consequence of the symmetric band structure of the nanotube. The excitation spectrum for metallic nanotubes exhibits four-fold shell filling and is completely described by an extended constant-interaction model. Furthermore, nanotubes with a four-fold shell structure are investigated in a parallel magnetic field. The magnetic field induces a large splitting between the two orbital states of each shell, demonstrating their opposite magnetic moment and determining transitions in the spin and orbital configuration of the quantum dot ground state. Also, a small coupling is found between orbitals with opposite magnetic moments leading to anti-crossing behaviour at zero field. Current–voltage characteristics of suspended carbon nanotube quantum dots show an additional series of steps equally spaced in voltage. The energy scale of this harmonic, low-energy excitation spectrum is consistent with that of the longitudinal low-k phonon mode (stretching mode) in the nanotube. Finally, we report on a fully tunable carbon nanotube double quantum dot. We perform inelastic transport spectroscopy via the excited states in the double quantum dot, a necessary step towards the implementation of new microwave-based experiments for quantum information technology.

The encapsulated copper atoms inside a defected single-walled carbon nanotube escape from the tube through the defect hole as the temperature increases. This causes the partially confined copper nanowires (CNWs) to undergo special structural transformations from a solid to a distinguishable helical layered structure and finally to the liquid state. The defect has a vital function in automatically adjusting the internal pressure and copper atom density. The critical structural transformation temperature of the CNW is significantly influenced by the confinement conditions of the carbon nanotube.

Multiwall carbon nanotube array/silicone elastomer composite films have been fabricated with an in situ injection modelling method. The transverse conductivity of the composite films is larger than the lateral conductivity because the aligned carbon nanotube array is embedded into the polymer matrix. The nonlinear I–V curve has been analysed and the temperature-dependent transport behaviour has been investigated.

We have examined the device characteristics of solution-processed single-walled carbon nanotube (SWNT) transistors. By using an electrical breakdown, SWNT-field-effect transistors (FETs) exhibited an on/off ratio (Ion/Ioff) of 104 and a field-effect mobility of 3.6 cm2 V-1 s-1 in air, which are comparable to those of other organic FETs. We investigated the detailed mechanism of carrier injection from electrode metals into SWNTs. From the temperature dependence of source–drain current, we evaluated the effective Schottky barrier height for holes to be 170 meV.

We have succeeded in homogeneously dispersing multi-walled carbon nanotubes (MWNTs) into an aluminum (Al) matrix by a novel elastomer precursor method. In thus prepared composite, the disentangled MWNTs were tightly bound to the Al matrix via oxygen-mediated AlN interfacial layer. The morphology of the composite surface was controlled by different polishing procedures and their field electron emission characteristics were investigated using a mesh-gate triode-type device. The MWNT/Al plate with well-rugged surface emitted electrons over a threshold electric field of 3 V/µm. The current density of 1 mA/cm2 was obtained at 6 V/µm and the luminance reached 400 cd/m2 under operation at 8 V/µm.

Single-walled carbon nanotubes are grown using grid-inserted plasma-enhanced chemical vapor deposition (PECVD). The field effect transistor operation was confirmed using the PECVD grown carbon nanotubes (CNTs). The preferential growth of the semiconducting nanotubes was confirmed in the grid-inserted PECVD by measuring current–voltage (I–V) characteristics of the devices. Based on the measurement of the electrical breakdown of the metallic CNTs, the probability of growing the semiconducting nanotubes has been estimated to be more than 90%.

A process for transferring carbon nanotube (CNT) arrays from a silicon wafer to an alumina substrate coated with Ag paste is proposed. A current density of up to 325?mA?cm?2 at an electric field of 2.4?V??m?1 was achieved. The influence of the patterned size and the length of carbon nanotubes on the field emission properties were investigated. Through this transfer method, the adhesion between the CNTs and the substrate is enhanced and the current density and turn-on voltage are improved. The effects of the microstructure of the emitting sites at the CNT tip on the current density were also studied.

Using a bond order potential, molecular dynamics simulations have been performed to study the mechanical properties of ultrathin single-walled carbon nanotubes with or without junction under uniaxial tensile loading. The ( 3, 3) armchair and ( 5, 0) zigzag nanotubes have been studied. Topological defects in the junction region influence the mechanical properties of junctions.

Quantum dots have been fabricated in single-wall carbon nanotubes (SWCNTs) simply by depositing metallic contacts on top of them. The fabricated quantum dots show different characteristics from sample to sample, which are even different in samples fabricated in the same chip. In this report, we study the statistical variations of the quantum dots fabricated with our method, and suggest their possible origin.

Third-order nonlinear susceptibility of single wall carbon nanotubes thin film was measured to be ~1.4u10 -16 m 2 /V 2 . The nonlinear transmission limiting threshold of carbon SWNT was ~20 MW/cm 2 with visible and nanosecond laser excitation.

We present experimental results on the electrical pulse-excited transport measurements of an individual single-wall carbon nanotube (SWNT) quantum dots. By applying a square pulse signal, the pulse-excited Coulomb peaks are observed in Coulomb oscillation measurements. In the SWNT quantum dot, the even-odd effect is confirmed by the alternate change of the Coulomb diamond size in the standard dc measurement. Magnetic fields perpendicular to the tube axis have revealed the simple Zeeman splitting of single particle states, this splitting is directly observed in the pulse-excited current in even-odd regime. We find the spin relaxation time at least longer than 1 µs.

Single-walled carbon nanotubes (SWNTs) were synthesized by pyrolyzing methane (CH4) at a temperature of 900 degrees C on SiO2 substrates pre-coated with iron nano-particles. Electrical contacts were fabricated onto one of the SWNTs by using an electron beam lithography process. Coulomb blockade and single-electron tunnelling characters were found at low temperatures, indicating that the SWNT in-between the electrodes forms a quantum dot. It is found that the Coulomb gap of the quantum dot is about 8.57 meV, and the factor a, which converts the gate voltage to the true electrostatic potential shift, is around 200 for this device.

We present experimental results on low-temperature transport of an individual single-wall carbon nanotube (SWNT) quantum dot. Four-electron shell structures were observed, due to the twofold subband degeneracy of the SWNT in addition to the twofold spin degeneracy. The excitation spectroscopy with a large source–drain voltage has made it possible to clearly observe the simple Zeeman splitting of single-particle states in a shell, and a textbook model of an interacting two-electron system has been demonstrated with directly distinguishable singlet and triplet states when the shell was half-filled.

Depending on the chirality, single-walled carbon nanotubes (SWNTs) can be either metallic or semiconducting. Thus far, the production of SWNTs, irrespective of synthesis methods, still yields a mixture of both types, with the metallic type being prevalent. However, semiconducting-type SWNTs are needed for carbon nanotube field-effect transistors (CNT-FETs) as well as many sensors. This is because only the semiconducting-type SWNTs can be effectively modulated by the gate voltage. In contrast, the lack of field effect in metallic-type SWNTs adversely impacts their applications in high-performance electronic devices. In this study, we demonstrate for the first time a novel plasma treatment method that allows us to convert metallic-type carbon nanotubes to semiconducting-type CNT-FETs. On the basis of our experimental results, we believe that the ion bombardment during Ar plasma treatment attacks both metallic- and semiconducting-type nanotubes; however, the metallic-type carbon nanotubes are more vulnerable to the attack than those of the semiconducting type, and are subsequently transformed into the latter type.

In this paper we report for the first time, the photoconductivity of large area sheets of single wall carbon nanotube upon laser illumination. The photoconductivity exhibited an increase, decrease or even 'negative' values when the laser spot was on different positions between contact electrodes, showing a 'position' dependent effect of photoconductivity. Photon induced charge carrier generation in single wall carbon nanotubes and subsequent charge separation across the metal?carbon nanotube contacts is believed to cause the photoconductivity changes. A net photovoltage of ~10?mV and a photocurrent of ~1.6?mA were produced under the laser intensity of ~160?mW with a quantum efficiency of ~1.5% in vacuum. The effect of the contact area between the electrodes and nanotubes, ambient pressure, laser intensity and light pulse frequency on the photoconductivity is discussed.

The electronic structure and quantum conductance of metallic carbon nanotube quantum dots and superlattices are investigated. We study two kinds of quantum dots and superlattices: rotationally symmetric and rotationally asymmetric ones. It is shown that rotational invariance significantly in.uences the conductance of quantum dots. In contrast, quantum conductance of superlattices (multiple quantum dots) does not critically depend on their rotational symmetry. All the calculations are performed within the tight-binding model and π-electron nearest-neighbors approximation.

Using molecular dynamics simulations, we show that a Y-junction carbon nanotube can be used to separate K+ and Cl− ions from a KCl solution. The Y-junction nanotube is formed by connecting two smaller carbon nanotube branches of sizes (5, 5) and (6, 6) to a larger (8, 8) carbon nanotube. While uncharged (5, 5) and (6, 6) carbon nanotubes show close to zero occupancy of K+ and Cl− ions, we show that a negatively charged (5, 5) carbon nanotube and a positively charged (6, 6) carbon nanotube can be selective to K+ and Cl− ions, respectively. By performing molecular dynamics simulations on the entire system comprising the Y-junction carbon nanotube, the KCl solution chamber, the push plate and the receiving chamber, we show that as the electrolyte moves through the (8, 8) carbon nanotube the K+ and the Cl− ions can be selectively transported through the (5, 5) and the (6, 6) carbon nanotube, respectively. The formation of ion pairs can affect the separation efficiency and we discuss the conditions under which perfect separation can be obtained.

Triton X-100 is used as a surfactant to disperse carbon nanotube (CNT) bundles. Its influence on the transfer characteristics of carbon nanotube field-effect transistors (CNTFETs) fabricated with the dispersed CNTs by the AC dielectrophoresis technique has been studied. We find that the surfactant at the interface between the CNTs and Au electrodes can change the work function of the electrodes and therefore convert the CNTFETs from typical p-type to having ambipolar characteristics. The adsorbed surfactant between the CNTs and SiO2 results in a significant hysteresis in the transfer characteristics of the CNTFETs.

Structures of the so-called super-carbon nanotubes are proposed. These structures are built from single walled carbon nanotubes connected by Y-like junctions forming a 'super'-sheet that is then rolled into a seamless cylinder. Such a procedure can be repeated several times, generating a fractal structure. This procedure is not limited to carbon nanotubes, and can be easily modified for application to other systems. Tight binding total energy and density of states calculations showed that the 'super'-sheets and tubes are stable and predicted to present metallic and semiconducting behaviour.

The electrical transport and chemical sensing properties of single-walled carbon nanotube field effect transistors (SWNT-FETs) coated with metal clusters have been investigated. The source–drain current passing through an SWNT-FET coated with Pd nanoparticles showed no change over a range of gate voltages. Nevertheless, the magnitude of the current was still sensitive towards NO2, NH3 and H2 exposure. The Pd nanoparticles coating on the nanotube generated hole carriers, which either became diluted upon NH3 or H2 adsorption, or enhanced upon NO2 adsorption. Unlike the ohmic behaviour demonstrated by SWNT-FETs coated with Pd nanoparticles, the transfer characteristics of SWNT-FETs coated with Al nanoparticles revealed Schottky barrier formations at the metal–nanotube contacts. Here, the conductance through the nanotube decreased, while the device sensitivity towards NO2 and NH3 gases improved greatly. We suggest that coating SWNT-FETs with metal nanoparticles could be exploited for the development of highly sensitive nanotube-based molecular sensors.

We have fabricated ordered arrays of nanoscale torsional actuators consisting of metal mirrors bonded to precisely oriented multiwall carbon nanotubes. The fabrication is facilitated by a new nanotube positioning method which employs localized electron beam activation of polymer residue on a silicon oxide surface.

We study the effect of doping transition metals (TMs) into single-wall carbon nanotubes by using first-principles calculations. For metallic isolated (3,3) single-wall carbon nanotubes, doping of Mn, Fe and Co makes them semi-metallic, while Ni doping leads to semiconductors. For (3,3) nanotube bundles, a Co atom in the unit cell makes it exhibit semiconductor character. With two or three Co and Ni atoms doped into the bundle, the impurity atoms change the nanotube to semi-metal. In particular, the Mn2C12 and Mn3C12 bundle have comparable large magnetic moments, suggesting that such TM-doped nanotubes could be useful as nanomagnets.

The interaction between an energetic ion and an atom of the carbon nanotube is approximated as that between a carbon atom and an sp2 carbon atom of a graphene sheet and computed using density functional theory utilizing a local density functional. Using the calculated force, molecular dynamics simulation of a low energy carbon ion moving in a single-wall carbon nanotube is conducted. Compared with the simulation using the ZBL potential, the result shows that the motion of the ion is quite different and the range is much shorter. The attractive part of the interatomic interaction is found to play an important role in the channelling of low energy ions in an SWCNT.

Ultrafast time-resolved optical transmissions in purified and as-grown single-walled carbon nanotube films are measured at a temperature of 200K. The signal of the purified sample shows a crossover from photobleaching to photoabsorption. The former and the latter are interpreted as the state filling and the red shift of the pi-plasmon, respectively. The signal of the as-grown sample can be perfectly fitted by a single-exponential with a time constant of 232fs. The disappearance of the negative component in the as-grown sample is attributed to the charge transfer between the semiconducting nanotubes and the impurities.

The effect of oxygen adsorption on a nanotube-based field effect transistor have been controversial as to whether it induces p-type doping of the nanotube body or the work function increase in the metal electrode. Here we report a transport measurement showing that a long individual single-walled nanotube can be doped as p-type upon oxygen adsorption. We discuss that, despite the fact that the charge transfer between the nanotube and O2 adsorbator has not been agreed to date, the effect of oxygen adsorption should still be interpreted as inducing p-type doping in the nanotube body. The n-type doping by NH3 adsorption is also measured for the purpose of comparison. Based on these observations, we suggest that, while the Schottky barrier management could be more effective for the transistor with a short nanotube, the doping effect could be more influential in devices with longer nanotubes.

The statistical variations in the properties of carbon nanotubes and their contacts to metallic electrodes can be averaged by using networks of single-walled carbon nanotubes as sensing devices. Carbon nanotube networks have been assembled on microstructures with dielectrophoresis, using an inhomogeneous alternating electric field to attract carbon nanotubes onto the microelectrodes. The networks were assembled on identical microstructures using four different frequencies in the range 10 kHz–10 MHz. From structural and electrical characterization of the assembled structures, we found that at higher frequencies the assembled nanotubes align better with the electric field and are more free of impurities. We also found consistently lower resistances for networks assembled at higher frequencies, suggesting that a high assembly frequency may lead to better quality networks with low contact resistances.

One important requirement for future applications of carbon nanotube electronic devices is the ability to controllably grow carbon nanotubes on metal electrodes. Here we show that it is possible to grow small diameter (

We investigated nanoscale engine schematics composed of a carbon nanotube oscillator, motor, channel, nozzle, etc. For the fluidic gas driven carbon nanotube motor, the origination of the torque was the friction between the carbon nanotube surface and the fluidic gases. The density and flow rate of the working gas or liquid are very important for the carbon nanotube motor. When multi-wall carbon nanotubes with very low rotating energy barriers are used for carbon nanotube motors, the fluidic gas driven carbon nanotube motors can be effectively operated and controlled by the gas flow rates. The variations of the flux were the same as the variations of the carbon nanotube oscillator. Although the carbon nanotube oscillator continually vibrated, since the angular velocity of the motor was saturated at a constant value, the speed of the nanoscale engine could be controlled by the frequency of the carbon nanotube oscillator below the maximum speed.

The conditions for single wall carbon nanotube formation in the arc discharge method of nanotube production are described. Carbon nanotube seed formation and charging in the interelectrode gap are found to be very important effects that may alter carbon nanotube formation on the cathode surface. The model predicts that the long carbon nanotubes formed in the relatively dense plasma region can be deposited on the cathode surface. The nanotubes in the cathode deposit are primarily oriented in the cathode surface plane and not along the electric field. This prediction is qualitatively confirmed by an SEM analysis of the cathode deposit.

In this study, single-walled carbon nanotube-based sensors are proposed for measuring strain and pressure at the nanoscale. The principle of sensing is based on the resonant frequency shift of a carbon nanotube resonator when it is subjected to a strain resulting from external loading. The carbon nanotube in a bridged configuration is simulated by atomistic modelling, the molecular structural mechanics method. The resonant frequency shifts are shown to be linearly dependent on the applied axial strain and the applied pressure. The sensitivities of nanotube-based sensors are enhanced with the reduction of tube length and tube diameter, respectively, for axial strain and pressure sensing.

Polycrystalline samples of multi-walled carbon nanotube (CNT) doped MgB2 superconductors were synthesized by solid state reaction. The carbon nanotube substitution results in a small decrease in lattice parameter and Tc, as compared to ordinary carbon substitution. Enhancement of Hc2 and Hirr shown by CNT doped samples show that the effect of CNT doping is two-fold. For sintering temperatures higher than 900 °C, the CNTs partially decompose, allowing substitution of boron for carbon. This results in an increased Hc2. However, remains of the CNTs are incorporated into the crystal matrix of MgB2, and they act as pinning centres. For lower sintering temperatures, there is little substitution of boron for carbon, and CNTs are incorporated into the crystal matrix as a whole, acting as pinning centres without affecting Hc2.

Cyanoacrylate–carbon nanotube arrays are prepared by embedding carbon nanotube (CNT) arrays grown on silicon substrate in cyanoacrylate adhesive. Upon laser treatment, enhanced field emission properties are obtained. Moreover, the binding force between the carbon nanotubes and the substrate is strengthened by the cyanoacrylate adhesive. When the field emission current is large enough at high electric field, the carbon nanotubes cannot be pulled out of the substrate by electric field force. A large field emission current can be obtained from cyanoacrylate–carbon nanotube arrays at relatively low voltage just by decreasing the distance between the anode and the cathode.

Using first-principles calculations, we investigate the comparative stability of sub-0.4 nm carbon nanotubes. Compared to the fullerenes C20 and C60, it is found that the most likely carbon nanotubes with a small diameter 0.3 nm are (2,2),(3,1) and (4,0) nanotubes. The spontaneous symmetry breaking of an isolated (2,2) nanotube produces an energy gap at the Fermi level converting it into a semiconductor. The curvature effects lowered the π* band to cross the Fermi energy, leading to the (4,0) nanotube being metallic.