A new carbon allotrope with orthorhombic symmetry formed via graphitic sheet buckling

We identified by ab initio calculations a new simple orthorhombic carbon allotrope with Pmc21 (C2v2) symmetry that has a 32-atom unit cell in all-sp3 hybridized covalent bonds.

Mechanical Properties of Single-Walled Carbon Nanotubes under Large Axial Deformation

The deformation of single-walled carbon nanotubes (SWCNTs) under large axial strain is studied by a geometrical mapping method. The interactions between atoms in carbon nanotubes (CNTs) are described by Tersoff-Brenner potential. Results show the strain energy depends on chirality but hardly on tubes’ radii. For graphitic sheet under large axial deformation, the elastic moduli decrease with the increase of engineering strain under tension. The modulus reaches the peak value as the axial engineering strain reaches -0.08 for armchair pattern and -0.15 for zigzag pattern under compression.

Synthesis and Characterization of Carbon Nanotubes by Using Catalyst LiNi0.5Co0.5O2 on Anodized Alumina Substrate

Carbon nanotubes (CNTs) have been synthesized by chemical decomposition of acetylene gas at 580°C and 650°C using catalyst of LiNi0.5Co0.5O2. The effect of decomposition temperature on structure of the CNTs is that, CNTs grown at 650°C have lower defects concentration and higher crystallinity as compared to that grown at 580°C. The porous anodized aluminum oxide (AAO) template (as substrate), catalyst particles and the CNTs grown were analyzed by FE-SEM. The pore diameter in the template lies in range of 30 - 80 nm. The CNTs have been analyzed by using Raman spectroscopy and X-ray diffraction techniques. The up-shift in G-band of graphitic sheet and larger full width at half maximum of the peak in the Raman spectra of the CNT in comparison to those observed for graphite are indicative of the structural modification. XRD results also indicate the structural modification in CNT based on the fact that d-value becomes 3.42 Å, which is larger than 3.35 Å for graphite. The tube diameters lie in the range of 12 - 50 nm.