科研之友
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摘要
In a recent report [Sun , Science 312, 1119 (2006)], the partially filled material inside multiwalled carbon nanotubes (MWNTs) was shown to have shrunk and deformed in the axial direction under 300 kV electron irradiation. In this experiment, 100 MeV Au7+ ion irradiation was performed to study the deformation and defects in uniformly nickel filled MWNTs with high-resolution transmission electron microscopy and Raman spectroscopy. We propose that high-pressure induced torsion in confined nickel could possibly result in successive compressions and expansions of the tubes, leading to axial buckling of MWNTs. The tangential Raman G band systematically upshifts as the ion fluence increases, attributed to the torsional strain. In contrast to a square root dependence of the buckling wavelength (lambda) on the radius (r) and thickness (t) of the tubes [lambda=3.5(rt)(1/2)], as predicted by theoretical models, the exponential fit of the data that assumes lambda proportional to e(root(r/t)) also produces an excellent fit.
- 出版日期2007-7
