Allometric Pressure versus Volume Behavior of Single-Walled Carbon Nanotubes Under High Pressure

Abstract

Single-walled carbon nanotubes (SWCNT) under high pressure have been studied by Raman spectroscopy. Considering cylindrical nanotubes with circular cross sections at all pressures the experimental data show an allometric pressure versus volume (PV) behavior under non-hydrostatic and quasi-hydrostatic conditions. We show that there is no need to consider a structural phase transition to explain the dependence of the radial breathing mode (RBM) phonon frequency with pressure. The bulk modulus (Bo) of the bundled nanotubes obtained from the PV data increases with pressure following a fit given by Bo = 2.38+10.77P GPa.