Carbon Nanotube Properties under High Pressure

The structure and physical properties of carbon nanotubes under high pressure up to 50.7 GPa were investigated using in situ high pressure energy dispersive X-ray diffraction with synchrotron radiation. At atmospheric pressure, the structure of carbon nanotubes is similar to the hexagonal close-packed lattice of graphite with the interplanar spacing of diffraction line (002) d002=0.340 4 nm and that of line (100) d100=0.211 6 nm. According to the high pressure X-ray diffraction results, diffraction results, diffraction line (002) is broadened and weakened above 8 GPa, and carbon nanotubes became partly amorphous. When pressure of 10 GPa and 20 GPa was down to zero, the diffraction line (002) was partly recovered. But at the maximum pressure of 50.7 GPa, they entirely became amorphous and this amorphous transition is irreversible. The equation of state of Birch-Murnaghan was used to obtain the bulk modulus .