Single wall carbon nanotube fibers extruded from super-acid suspensions: Preferred orientation, electrical, and thermal transport

Abstract

Fibers of single wall carbon nanotubes extruded from super-acid suspensions exhibit preferred orientation along their axes. We characterize the alignment by x-ray fiber diagrams and polarized Raman scattering, using a model which allows for a completely unaligned fraction. This fraction ranges from 0.17 to 0.05±0.02 for three fibers extruded under different conditions, with corresponding Gaussian full widths at half-maximum (FWHM) from 64 o to 44 o ±2 o . FWHM, aligned fraction, electrical and thermal transport all improve with decreasing extrusion orifice diameter. Resistivity, thermoelectric power and resonant-enhanced Raman scattering indicate that the neat fibers are strongly p-doped; the lowest observed ρ is 0.25mΩcm at 300 K. High temperature annealing increases ρ by more than 1 order of magnitude and restores the Raman resonance associated with low-energy van Hove transitions, without affecting the nanotube alignment.

Carbon Nanotubes for Electronic and Electrochemical Detection of Biomolecules

“…This interface is schematically illustrated as a tapered zone in Figure 3a 6 and a 8 , where Schottky barrier modulation of SWNT-FETs takes place. [104] Normally, adsorption of the biomolecular recognition moieties occurs not only onto nanotube sidewalls but also on this tapered-thin metal-SWNT Schottky junction.…”

“…However, one has to be aware that unlike double-stranded DNA, [102] single-stranded DNA adheres strongly onto SWNTs by wrapping around them. [65,106] This renders DNA hybridization less favorable at the SWNT surface as compared to the metal/ nanotube Schottky junction, [102] which is schematically shown in Figure 3a 8 . The introduction of divalent cations (i.e., Mg 2+ , Co 2+ , Ca 2+ , and Hg 2+ ) screens the repulsion between DNA chains and promotes greater adsorption of DNA-oligomers onto this junction.…”

“…[1][2][3] CNTs have the potential to revolutionize numerous applications where nano-sized metallic and/or semiconducting components are required along with high strength, [4,5] large flexibility [6] and superb chemical stability. [7,8] In particular, metallic (met-) nanotubes are highly suited for nanoscale circuits, [9] ultrathin, flexible, and transparent conductors, [10] supercapacitors, [11] field emitters, [12] actuators, [13] and nanosized electrochemical probes. [14] Semiconducting (sem-) CNTs on the other hand, are applicable for nanoscale sensors, [15,16] transistors, [17,18] and photovoltaic devices.…”

Single-walled carbon nanotubes in superacid: X-ray and calorimetric evidence for partly orderedH2SO4

“…The mechanism of charge transfer as the driving force for partly ordered acid shells is also supported by the observation of strongly metallic behavior in acid-doped SWNT. 8,18 We acknowledge helpful discussions with M. …”

“…Intense Bragg reflections with azimuthal preferred orientation are attributed to the aforementioned aligned SWNTs in semicrystalline ropes, while strong small-angle x-ray scattering ͑SAXS͒ diffuse intensity is assigned to the structural inhomogeneity on large length scales ͑aligned ropes vs voids between ropes͒, 8 discussed in detail below. The dotted line in Fig.…”