Abstract
The analysis of the radial collapse of individualized and isolated
single-wall carbon nanotubes under high pressure as function of their
diameter, d, distinguishes their mesoscale and their nanoscale
mechanics. The evolution with pressure of the Raman spectra for nine
tube chiralities and the theoretical modelling reveal a deviation from
the continuum mechanics prediction of a collapse pressure P-C
proportional to d(-3). Nanotubes show a normalized collapse pressure P-N = P(C)d(3) = 24 alpha D(1 - beta(2)/d(2)) both in experiment and in very different theoretical models. In this expression beta = 0.44 +/- 0.04 nm
represents the smallest diameter for a stable freestanding single-wall
carbon nanotube and D is the bending stiffness of graphene. From the experimental data D = 1.7 +/- 0.2 eV. Deviations from the continuum
mechanics predictions start to be of significance for diameters smaller
than similar to 1 nm. The associated reduction of their collapse
pressure is attributed to the discretization of the elastic compliances
around the circumference of the tubes. (C) 2017 Elsevier Ltd. All rights
reserved.
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