High structural stability of single wall carbon nanotube under quasi-hydrostatic high pressures

In quasi-hydrostatic conditions, single wall carbon nanotubes (SWNTs) exhibit high structural stability to ∼35 GPa, well beyond the stability of sp2 CC bonds in graphite, carbon fullerenes, benzene, and other hydrocarbons. The pressure-induced Raman changes of SWNT are completely reversible below 16 GPa, partially reversible between 16 and 35 GPa, and irreversible beyond 35 GPa where it turns into highly disordered graphite. We explain the high stability in terms of the pressure-induced structural modification to an interlinked configuration, which occurs reversibly under substantial sp3 hybridization (∼20%) and, thus, increases the stability of sp2 CC bonds in the SWNTs.