Pressure-Induced Phase Transitions of Single-Walled Carbon Nanotubes: Simulations of X-Ray Diffraction

Pressure-induced structural changes of single-wall carbon nanotubes organized into two-dimensional crystalline bundles are studied by simulating X-ray diffraction. The sizable variation in the Bragg peak position with pressure appears as the induced hydrostatic pressure deforms the tubular cross section. We calculated the X-ray profiles of different simulated nanotube geometries upon the application of hydrostatic pressures ranging from 0 to 4.5 GPa. It was found that an increase in the hydrostatic pressure results in a downshift in the 2 theta angle of the nanotubes; in addition, as a response to the increase in the hydrostatic pressure, the X-ray intensity increased systematically in all profiles.