Polymerization of Single-Wall Carbon Nanotubes under High Pressures and High Temperatures

Abstract

Survey studies of pressure−temperature-induced transformations of single-wall carbon nanotubes (SWNT) at 1.5, 8.0, and 9.5 GPa and temperatures ranging from 200 to 1500 °C in a piston-cylinder or “Toroid” type high pressure devices have been carried out. It was found that the combined effects of high pressures and high temperatures produce irreversible changes in the SWNT structure, in contrast with the reversible effect of high pressure alone, previously studied by several research groups. The Raman, electron microscopy, and X-ray diffraction data obtained in the present work provide evidence for covalent interlinking of SWNT by sp3 C−C bonds which escalates with the increasing treatment temperature and pressure. The formation of new carbon structures such as nano- and microcrystalline diamond-like (cubic and hexagonal) and nanographite phases under higher pressures (8.0 and 9.5 GPa) has been observed.

Covalent-bonded graphyne polymers with high hardness

“…Other carbon allotropes are more readily transformed into superhard carbon materials. For instance, fullerene C 60 can polymerize to 3D superhard carbon phase above 13 GPa; in addition, CNTs are transformed into diamond-like carbon allotropes at 8.5-9 GPa pressure and further compressed into an sp 3 -hybridization bonded superhard carbon phase under 16 GPa [6][7][8][9]. Compared with stable graphite, metastable carbon allotropes are growing into new precursors for synthesizing hard carbon materials under moderate conditions.…”

XRD and TEM study of high pressure treated single-walled carbon nanotubes and C60-peapods

“…High pressure behaviors of carbon nanotubes have also been investigated by X-ray diffraction (XRD), Raman scattering and so on [8][9][10][11][12][13][14][15][16][17]. There are many reports on high pressure behavior of SWNTs using a diamond anvil cell (DAC) at room temperature, while only a few HPHT experiments of SWNT sample were reported.…”

“…There are many reports on high pressure behavior of SWNTs using a diamond anvil cell (DAC) at room temperature, while only a few HPHT experiments of SWNT sample were reported. Khabashesku et al [15] have done transmission electron microscope (TEM) observation and Raman scattering, XRD measurements of the SWNT samples HPHT treated up to 9.5 GPa, 1873 K and discussed the possibility of polymerization of SWNTs. Unfortunately, since the SWNT sample used in their experiment was not well crystallized and did not exhibit any diffraction peaks, it is difficult to discuss the structural change of bundle crystal by HPHT treatment.…”

Multiporous carbon allotropes transformed from symmetry-matched carbon nanotubes

“…Compressing CNTs yields more interesting but perplexing phases owing to the structural complexity of CNTs, such as chirality, diameter, single-wall or multi-wall. 20,[38][39][40][41][42][43] However, with the development and improvement of experimental techniques, small and homogeneous CNTs might be achieved and used as fundamental building block for other structures or devices. Actually, many studies have been performed to achieve this goal.…”