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Single Wall Carbon Nanotubes (single + wall_carbon_nanotube)
Selected AbstractsActuating Single Wall Carbon Nanotube,Polymer Composites: Intrinsic Unimorphs,ADVANCED MATERIALS, Issue 11 2008Cheol Park A novel actuating single wall carbon nanotube (SWNT)/polymer composite is reported. It exhibits a large strain (2.6%) at a low driving voltage (<1 MV m,1) while possessing excellent mechanical and thermal properties. The strain energy density is at least an order of magnitude greater than any state-of-the-art polymeric materials reported. The actuating characteristic mainly originates from the electrostrictive contribution, presumably due to interfacial polarization. [source] Electron paramagnetic resonance and non-resonant microwave absorption of single wall carbon nanotubesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007B. Corzilius Abstract Single wall carbon nanotubes (SWNT) prepared by the "super growth" method exhibit electron paramagnetic resonance (EPR) signals, which originate from temperature activated detrapping of spins. Non-resonant microwave absorption in the temperature range below 20 K is indicative for the opening of a small gap at the Fermi level for tubes of metallic character, which might indicate a transition into a superconducting (SC) state. The expected concurrent microwave field inhomogeneity has been detected by a transient nutation experiment. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electroreduction of Oxygen and Electrooxidation of Methanol at Carbon and Single Wall Carbon Nanotube Supported Platinum ElectrodesELECTROANALYSIS, Issue 10 2008Ahmad, Nozad Golikand Abstract The present research aimed at investigating the electrocatalytic properties and the electrochemical deposition of Pt nanoparticles on carbon powder, carbon nanotube and preparation of carbon and single wall carbon nanotube supported platinum electrodes. The Pt nanoparticles were synthesized by electroreduction of hexachloroplatinic acid in aqueous solution at ,200,mV. Electrocatalytic properties of the modified electrodes for oxygen reduction were investigated by cyclic voltammetry in O2 saturated solution containing 0.1,M HClO4. Methanol electrooxidation at the modified surfaces in 0.5,M HCLO4 was studied by cyclic voltammetry. The corresponding results showed that the Pt/SWCNT/GC electrode exhibits more improved catalytical activity than the Pt/C/GC electrode. [source] Actuating Single Wall Carbon Nanotube,Polymer Composites: Intrinsic Unimorphs,ADVANCED MATERIALS, Issue 11 2008Cheol Park A novel actuating single wall carbon nanotube (SWNT)/polymer composite is reported. It exhibits a large strain (2.6%) at a low driving voltage (<1 MV m,1) while possessing excellent mechanical and thermal properties. The strain energy density is at least an order of magnitude greater than any state-of-the-art polymeric materials reported. The actuating characteristic mainly originates from the electrostrictive contribution, presumably due to interfacial polarization. [source] A transmission line model for metallic carbon nanotube interconnectsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 1 2008A. Maffucci Abstract A transmission line (TL) model describing the propagation of electric signals along metallic single wall carbon nanotube (CNT) interconnects is derived in a simple and self-consistent way within the framework of the classical electrodynamics. The conduction electrons of metallic CNTs are modelled as an infinitesimally thin cylindrical layer of a compressible charged fluid with friction, moving in a uniform neutralizing background. The dynamic of the electron fluid is studied by means of the linearized hydrodynamic equations with the pressure assumed to be that of a degenerate spin-½ ideal Fermi gas. Transport effects due to the electron inertia, quantum fluid pressure and electron scattering with the ion lattice significantly influence the propagation features of the TL. The simplicity and robustness of the fluid model make the derivation of the TL equations more straightforward than other derivations recently proposed in the literature and provide simple and clear definitions of the per unit length (p.u.l.) TL parameters. In particular, this approach has provided a new circuit model that can be used effectively in the analysis of networks composed of CNT transmission lines and lumped elements. The differences and similarities between the proposed model and those given in the literature are highlighted. Copyright © 2006 John Wiley & Sons, Ltd. [source] Electrical transport properties of a single wall carbon nanotube networkPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2009J. S. Hwang Abstract A single wall carbon nanotube (SWCNT) network is fabricated and its electronic transport properties are investigated. It shows a typical p-type field-effect-transistor (FET) behavior and nonlinearities in the source current-source bias characteristics. The network also exhibits incomplete turn-off and a small mobility. These characteristics are explained by the fact that the network is a mixture of metallic and semiconducting SWCNTs connecting with one another. Various cross junctions such as SWCNT (semiconducting)-SWCNT (semiconducting), SWCNT (semiconducting)-SWCNT (metallic) are the source of nonlinearities and the small mobility. Incomplete turn-off can be explained by the parallel conduction paths consisting of metallic SWCNTs which are insensitive to the gate bias. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nonlinear surface electrical resistivity of graphite,polyurethane composite filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Ganesh K. Kannarpady Abstract In this article, we study the surface resistivity of graphite,polyurethane composites using voltage,current characteristics. The evolution of the percolation network of graphite in polyurethane is qualitatively studied using optical micrographs. As expected, the surface resistivity decreases as a function of graphite concentration. In particular, the surface resistivity of the 69% graphite,polyurethane composite is about four orders of magnitude lower than the surface resistivity of the 27% graphite,polyurethane composite. The electrical resistivity of the composite is found to be highly nonlinear with respect to an increasing voltage at a low graphite weight fraction. On the other hand, the nonlinearity is significantly milder at higher weight fractions. The reasons behind the nonlinearity are discussed. Very preliminary studies indicate that very low weight fractions of single wall carbon nanotubes (e.g. 2.5%) are sufficient to generate electrical conductivities comparable to much higher loading fractions (, 60% and higher) of the heavier graphite particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Synthesis of PEGylated single wall carbon nanotubes by a photoinitiated graft from polymerizationAICHE JOURNAL, Issue 6 2010Pu Zhang Abstract A considerable amount of research has been devoted to carbon nanotubes because of their unique electrical, mechanical, optical, and chemical properties. Here, in this report, we introduce a novel, simple ultraviolet initiated "graft from" polymerization method to synthesize PEGylated carbon nanotubes. This grafting procedure significantly enhanced nanotube aqueous dispersibility and long term stability in solution. Mass of grafted polymer chains was easily modulated by adjusting polymerization reaction time, and nanomaterials containing up to 80% polymer by weight were synthesized. Nanotube morphology was characterized by SEM, TEM before and after the functionalization. In addition, the covalent bonding of polymer chains to the nanotubes structure was elucidated by Raman, ATR-FTIR, and XPS spectroscopy. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Transparent carbon nanotube field emission devices for display and lampPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007Yousuk Cho Abstract A new, simple method to fabricate transparent carbon nanotube field emission devices is developed. The highly graphitized, single wall carbon nanotubes (SWNTs) are attached to an Sn/ITO glass by the arc discharge method. Post-heat treatments of the sample below the deformation temperature of soda-lime glass form a Sn,SWNT composite, and the nanotubes form good mechanical adhesion and electrical contact with the substrates. When the composite is oxidized in air below 400 °C, the Sn particles change to a transparent oxide form. The emission current density of the heat-treated SWNT,Sn composite is about 1 mA/cm2 at an electric field of 3 V/,m. The emission current density of the SWNT,SnOx composite is similar. However, at a higher oxidation temperature, the emitter shows more stable emission property and longer life time. The transparency of the emitter can be useful in the design of emitter devices. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Carbon nanotube based composites for electronic applications: CNT,conducting polymers, CNT,CuPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006N. Ferrer-Anglada Abstract We performed two different types of composites using single wall carbon nanotubes: 1) transparent electrodes, using a thin network of carbon nanotubes as electrode on which we can grow a conducting polymer electrochemically on it, polyaniline or polypirrole, CNT,CP; the obtained thin films are both transparent (transmission coefficient T from 70% to 95%) and electrically conducting. The samples were observed by AFM, optical and Raman spectroscopy, room temperature electrical conductivity were performed. 2) CNT with a metal, copper in our case (CNT,Cu), as a material with high electrical and thermal conductivity and low coefficient of thermal expansion (CTE), to be used in electronic packaging. We observed the samples by AFM and SEM. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] G-mode behaviour of closed ended single wall carbon nanotubes under pressurePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2009Ahmad J. Ghandour Abstract We have performed high pressure Raman experiments on closed-ended single wall carbon nanotubes using two different excitation wavelengths: 632.8 nm and 514 nm. We found that the shape of the G-mode spectrum changes while changing the excitation wavelength at lower pressures, while it becomes similar at 3.5 GPa. In addition we record that the value of the transition pressure, associated with the structural transitions in the tubes, has also changed with changing the excitation wavelength even though we are examining tubes from the same produced sample. We attribute these results to the tubes having different electronic nature (metallic; semi-conducting) and different diameters in resonance with each excitation wavelength. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The role of environmental effects on the optical transition energies and radial breathing mode frequency of single wall carbon nanotubesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2008P. T. Araujo Abstract In this paper we discuss the environmental effects on the radial breathing mode (RBM) spectra of Single Wall Carbon Nanotubes (SWNTs). We have shown that the environmental effect on the radial breathing mode frequencies can be explained by Van-der-Waals interactions. We here explore these interactions concerning its (n,m) dependence and curvature effects. Furthermore, most of the optical transition energies available in the literature (ELit.ii) are downshiftedwith respect to the optical transition energies for super-growth (S.G.) tubes (ES.G.ii). The effect on transition energies can be understood considering the effect of the dielectric constant of the medium in the excitonic optical transition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electron paramagnetic resonance and non-resonant microwave absorption of single wall carbon nanotubesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007B. Corzilius Abstract Single wall carbon nanotubes (SWNT) prepared by the "super growth" method exhibit electron paramagnetic resonance (EPR) signals, which originate from temperature activated detrapping of spins. Non-resonant microwave absorption in the temperature range below 20 K is indicative for the opening of a small gap at the Fermi level for tubes of metallic character, which might indicate a transition into a superconducting (SC) state. The expected concurrent microwave field inhomogeneity has been detected by a transient nutation experiment. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The fundamental aspects of carbon nanotube metrologyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007Ado Jorio Abstract The accurate and reproducible measurement of the properties and performance characteristics of nanoscale materials, devices and systems are essential for quality and process control, commercial transactions and effective regulations. Scientists, manufacturers, governments, regulators and health and environmental protection agencies, will need measurement systems and evaluation protocols supported by well founded and robust standards, both physical and documentary. In this paper we discuss some fundamental aspects of the use of the resonance Raman spectroscopy of the radial breathing mode (RBM) of single wall carbon nanotubes (SWNTs) for metrological purposes. The achievements and problems are pointed, hoping for the development of procedures capable of making the promised nanotechnology revolution to become a reality. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A photoemission study of the metallic ground state of potassium-doped C60 peapodsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2006H. Rauf Abstract We report on the doping dependence of the electronic structure of the valence band of mats of C60 -filled single wall carbon nanotubes (C60 peapods) studied by high resolution photoemission spectroscopy. In the pristine state, the bundles consist of approximately one third metallic tubes which are Tomonaga,Luttinger liquids (TLL) and thus show a power law scaling of the density of states near the Fermi level. The power law scaling factor of the pristine peapods is hardly increased compared to that of single-walled carbon nanotubes (SWCNT). Upon doping we find a complex doping behavior and charge distribution between the electronic states of the SWCNT and the encaged C60 chains. Close to the Fermi level this has consequences on the doping induced crossover from a TLL to a conventional Fermi liquid which is found at a higher charge transfer as compared to intercalated SWCNT bundles. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||