Studies on high pressure behavior of carbon nanotubes: X-ray diffraction measurements using synchrotron radiation

High-pressure behavior of novel one-dimensional material - carbon nanotubes (single-walled and multi-walled, pristine and Fe-filled) have been investigated by in situ powder X-ray diffraction (XRD) studies. Single-walled nanotubes show remarkable mechanical resilience. The presence of non-hydrostatic stresses makes compression behavior much different from that under the hydrostatic stress. Our results also suggest pressure-induced elliptization of the tubes in a bundle. Iron-filled multi-walled nanotubes, unlike pristine, show a structural modification at a pressure of ∼9 GPa where the outer component (Fe3C) of the encapsulated nanowire undergoes an iso-structural transition. Also the high-pressure behavior of the α-Fe is quite different from the bulk.