Recently discovered carbon nanotubes have exhibited many unique material properties including very high thermal conductivity. Strong sp 2 bonding configurations in carbon network and nearly perfect self-supporting atomic structure in nanotubes give unusually high phonon-dominated thermal conductivity along the tube axis, possibly even surpassing that of other carbon-based materials such as diamond and graphite (in plane). In this chapter, we explore theoretical and experimental investigations for the thermal-transport properties of these materials.

Unusually High Thermal Conductivity of Carbon Nanotubes

Thermal conductivity of carbon nanotubes and their polymer nanocomposites: A review

Carbon nanotubes are unique tubular structures of nanometer diameter and large length/diameter ratio. The nanotubes may consist of one up to tens and hundreds of concentric shells of carbons with adjacent shells separation of ∼0.34 nm. The carbon network of the shells is closely related to the honeycomb arrangement of the carbon atoms in the graphite sheets. The amazing mechanical and electronic properties of the nanotubes stem in their quasi-one-dimensional (1D) structure and the graphite-like arrangement of the carbon atoms in the shells. Thus, the nanotubes have high Young’s modulus and tensile strength, which makes them preferable for composite materials with improved mechanical properties. The nanotubes can be metallic or semiconducting depending on their structural parameters. This opens the ways for application of the nanotubes as central elements in electronic devices including field-effect transistors (FET), single-electron transistors and rectifying diodes. Possibilities for using of the nanotubes as high-capacity hydrogen storage media were also considered. This report is intended to summarize some of the major achievements in the field of the carbon nanotube research both experimental and theoretical in connection with the possible industrial applications of the nanotubes.

Carbon nanotubes: properties and application

The Element Carbon Frank Hennrich, Valerie Moore, Marco Rolandi, and Mike O'Connell Allotropes of Carbon History Structure Progress of Single-Walled Carbon Nanotube Research toward Application References Synthesis of Carbon Nanotubes David Mann Introduction CNT Synthesis Methods Overview Specifics of CVD Growth Method Recent Advances in SWCNT Growth Control Conclusion References Carbon Nanotube Peapod Materials Satishkumar B. Chikkannanavar, Brian W. Smith, and David E. Luzzi Introduction and Historical Perspective C60@SWNT Beyond C60: Other Hierarchical Nanotube Materials Ordered Phases of Fullerenes in Larger Nanotubes Double-Wall Carbon Nanotubes Conclusions and Future Prospects Acknowledgments References Carbon Nanotube Electronics and Devices Marcus Freitag Metallic Carbon Nanotubes Semiconducting Carbon Nanotubes Outlook and Challenges References Magnetic Properties Junichiro Kono and Stephan Roche Introduction Theoretical Perspectives Experimental Results Acknowledgments References Raman Spectroscopy of Single-Walled Carbon Nanotubes: Probing Electronic and Chemical Behavior Stephen K. Doorn, Daniel Heller, Monica Usrey, Paul Barone, and Michael S. Strano Introduction Resonance Raman Studies of Carbon Nanotubes Raman Characterization of Nanotube Samples and Nanotube Reactivity Conclusions References Electromechanical Properties and Applications of Carbon Nanotubes Randal J. Grow Introduction Piezoresistance Theory of Strain-Induced Band-Gap Changes in Carbon Nanotubes Electrical Measurements of Strain-Induced Band-Gap Changes in Suspended Tubes Electrical Measurements of Strain-Induced Band-Gap Changes in Tubes on a Surface Conclusion of Piezoresistance of Nanotubes Electrostatic actuation Nanoelectromechanical systems Conclusion References Carbon Nanotube-Enabled Materials Han Gi Chae, Jing Liu, and Satish Kumar Introduction Dispersion and Processing Issues Characterization of Polymer/CNT Composites CNT Films and Fibers Polymer/CNT Composite Films and Fibers Crystallization, Wrapping, Interaction, and Intercalation Concluding Remarks Acknowledgment References Functionalized Carbon Nanotubes in Composites Christopher A. Dyke and James M. Tour Introduction SWNT Preparation and Characterization Functionalized SWNTs Carbon Nanotube-Modified Composites Conclusions Acknowledgments References Carbon Nanotube Tips for Scanning Probe Microscopy C. Patrick Collier Carbon nanotubes as AFM probes Fabrication of nanotube probe tips AFM imaging with nanotube probes Applications of carbon nanotube probes Future directions Acknowledgments References Index

Carbon Nanotubes: Properties and Applications

▪ Abstract This account reviews the discovery, synthesis, properties, and the latest research advances of carbon nanotubes developed over the past 12 years. Because of their remarkable electronic and mechanical properties, carbon nanotubes are unique and exciting. The field has been developed rapidly, and the number of publications per year is increasing almost exponentially. Various technological applications are likely to arise using nanotubes for fabrication of flat panel displays, gas storage devices, toxic gas sensors, Li+ batteries, robust and lightweight composites, conducting paints, electronic nanodevices, etc. Further experimental and theoretical research is still necessary so that novel technologies will become a reality in the early twenty-first century.

Science and Technology of the Twenty-First Century: Synthesis, Properties, and Applications of Carbon Nanotubes

The specific heat and thermal conductivity of millimeter-long aligned carbon multiwall nanotubes (MWNT's) have been measured. As a rolled-up version of graphene sheets, a MWNT of a few tens nm diameter is found to demonstrate a strikingly linear temperature-dependent specific heat over the entire temperature range measured (10--300 K). The results indicate that interwall coupling in MWNT's is rather weak compared with its parent form, graphite, so that one can treat a MWNT as a few decoupled two-dimensional single wall tubules. The thermal conductivity is found to be low, indicating the existence of substantial amounts of defects in the MWNT's prepared by a chemical-vapor-deposition method.

Linear specific heat of carbon nanotubes

Both the magnetoconductance and the nonlinear differential conductance of multiwall carbon nanotube ropes have been studied at low temperture. Suppression in the differential conductance was observed at low bias voltages and at low temperatures, indicating the formation of a Coulomb gap. The magnetoconductance was found to follow a scaling law at both high and low temperatures, but with different mechanisms. The analysis of the data provides a sign of a non-Fermi-liquid-like behavior through magnetotransport measurement.

Consistent picture of strong electron correlation from magnetoresistance and tunneling conductance measurements in multiwall carbon nanotubes

We theoretically investigate the quantum path interferences in interband transitions in solid high-order harmonic generation. The field strength scaling of the 19th harmonic yield from MgO crystal driven by 1600-nm lasers exhibits a sharp minimum. By solving the semiconductor Bloch equation, we separate the short and long trajectories. Our numerical calculation shows that this minimum originates from the coherent interferences between the short and long trajectories. We also illustrate that the interference minimum depends sensitively on the band dispersion, which can be used to retrieve the band structure accurately. We further report that the two-color fields can select the short or long quantum path effectively by controlling the phase. The yield at the plateau or cutoff region of the harmonic spectra can be enhanced by around one order of magnitude by adding a third harmonic with an intensity of only $10%$ of the fundamental field. Moreover, an isolated attosecond pulse (IAP) is synthesized by controlling the harmonic trajectories in the two-color scheme. The yield of this IAP is enhanced by one order of magnitude compared with the IAP generated by the single-color scheme.

Quantum path interferences and selection in interband solid high-order harmonic generation in MgO crystals

High harmonic generation (HHG) in solids provides us compact and coherent extreme ultraviolet sources. However, the low yield of HHG is the bottleneck restricting its wide applications. We propose a pump-probe scheme to selectively enhance the yield of HHG. Our simulations illustrate abnormal harmonic yield dependence on the intensity of driving or preexcitation pulses. A multielectron interference model is proposed to reveal the mechanism of the extreme nonlinear optical phenomena. We find that the $k$-resolved intraband harmonic demonstrates different symmetry, phase, and amplitude, which can be observed by using a resonant preexcitation pulse. The position of the interference minimum obtained by solving the semiconductor Bloch equations agrees well with that obtained by our $k$-resolved semiclassical model. This interference model can help us probe the $k$-resolved band structure and optimize the ultrafast electron-hole dynamics for solid harmonic processes.

L. Lu

Papers

Linear specific heat of carbon nanotubes

Consistent picture of strong electron correlation from magnetoresistance and tunneling conductance measurements in multiwall carbon nanotubes

Quantum path interferences and selection in interband solid high-order harmonic generation in MgO crystals

Multielectron interference of intraband harmonics in solids

Linear conductance of multiwalled carbon nanotubes at high temperatures