High purity multiwalled carbon nanotubes under high pressure and high temperature

Abstract We have studied the structural modifications that multi-walled carbon nanotubes (MWNTs) undergo when treated under high pressure and high temperature (HP–HT). Uniaxial pressures of 5.5–6.5 GPa were applied to samples of purified MWNTs between 850 and 950 °C for 30 min. The resulting material was then analysed by X-ray diffractometry, Raman spectroscopy and transmission electron microscopy. Comparison of the data obtained by such analyses before and after treatment does show changes in the Raman spectra, a slight linear decrease of the d 002 spacing, and some structural modifications that could be due to MWNT segmentation and interlinking.