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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 64o to 44o±2o. 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.
Zhou, W., Vavro, J., Guthy, K., Winey, K. I., Fischer, J. E., Ericson, L. M., Ramesh, S., Saini, R. K., Davis, V. A., Kittrell, C., Pasquali, M., Hauge, R. H., & Smalley, R. E. (2004). Single Wall Carbon Nanotube Fibers Extruded from Super-Acid Suspensions: Preferred Orientation, Electrical and Thermal Transport. Retrieved from http://repository.upenn.edu/mse_papers/49
Date Posted: 21 January 2005
This document has been peer reviewed.