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Pure Appl. Chem. Vol.
74, No. 9, pp. 1719-1730 (2002)
Pure and Applied
Vol. 74, Issue 9
Electrochemical tuning and mechanical resilience of single-wall
Shankar Ghosh, Pallavi V. Teredesai, and A. K. Sood**
Department of Physics, Indian Institute of Science,
Bangalore 560 012, India
Abstract: Single-wall carbon nanotubes (SWNTs) are fascinating
systems exhibiting many novel physical properties. In this paper, we
give a brief review of the structural, electronic, vibrational, and
mechanical properties of carbon nanotubes. In situ resonance Raman scattering
of SWNTs investigated under electrochemical biasing demonstrates that
the intensity of the radial breathing mode varies significantly in a
nonmonotonic manner as a function of the cathodic bias voltage, but
does not change appreciably under anodic bias. These results can be
quantitatively understood in terms of the changes in the energy gaps
between the 1D van Hove singularities in the electron density of states,
arising possibly due to the alterations in the overlap integral of p
bonds between the p-orbitals of the adjacent
carbon atoms. In the second part of this paper, we review our high-pressure
X-ray diffraction results, which show that the triangular lattice of
the carbon nanotube bundles continues to persist up to 10
GPa. The lattice is seen to relax just before the phase transformation,
which is observed at 10
GPa. Further, our results display the reversibility of the 2D lattice
symmetry even after compression up to 13 GPa well beyond the 5 GPa value
observed recently. These experimental results explicitly validate the
predicted remarkable mechanical resilience of the nanotubes.
* Special Topic Issue on the Theme
of Nanostructured Advanced Materials
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