Hardness of high-pressure high-temperature treated single-walled carbon nanotubes

C60and C70pressure-and-temperature transformations into fullerene-related forms

“…It is known that the C 60 fullerene material can transform into the hard disordered states during the high-pressure-high-temperature treatment below 13 GPa [10]. At the same time, unlike C 60 , nanotubes do not produce the same hard and stiff phases below 13 GPa[30]. This may be related to the absence of pentagons in nanotubes (only some ball-shaped caps and curvatures of some nanotubes may contain pentagons…”