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Using a symmetry-based force-constant model of the lattice dynamics, the Raman-active phonon frequencies are calculated for almost 200 single-wall nanotubes of C, BN and BC(3). The n+m=constant family behaviour is found in most branches and these three kinds of nanotubes display different diameter and chirality dependence in different branches. In these branches, vibration modes that C, BN and BC(3) nanotubes have in common are presented in detail. For a particular family, the phonon frequency at Gamma point changes regularly with the chiral angle. Therefore, we may distinguish among single-wall nanotubes with similar diameter and different chiral angle.

The lithium adsorption energies, electronic structures, and properties for single‐walled blue phosphorus nanotubes (SWBPNTs) doped with B, C, N, and Si upon Li intercalation on the inside and outside surfaces are investigated using density functional methods. It is found that the dopants of B, C, N, and Si have negative formation energies. The structure and properties of the SWBPNT will undergo certain changes after doping. Due to the interaction of dopant atoms and P atoms, the bandgap of the nanotubes doped with B and N will be reduced, and the nanotubes doped with C and Si have defects (dopant) state in the forbidden band. For the dopant atoms in SWBPNT, B and Si lose electrons, while C and N gain electrons. Compared with pristine SWBPNT, when Li is adsorbed internal to the tube, the lithium adsorption energies in the doped SWBPNT have a larger negative value, especially for C and Si doping. Consequently, our work suggests that the B‐, C‐, N‐, and Si‐doped SWBPNT have the capability to enhance the Li adsorption capacity. [ABSTRACT FROM AUTHOR]

We investigate the size dependence of geometric structure and elastic properties of phosphorene nanotubes (PNTs) with armchair and zigzag forms, by using ab initio periodic quantum chemical method combining with the linear combination of atomic orbitals. Nanotubes are constructed by rolling up the non-planar honeycomb (010) two dimensional conventional monolayer. To explain the strength of bonding between P atoms, the bending stiffness and the amount of charge transfer have been calculated. We obtained different values of bending stiffness that for the PNTs rolled up along the two directions, which shows that the bending stiffness is changing with different chiralities. Our calculations also indicate that the distance between inner and outer atoms increases monotonically with increasing radius, while the charge transfer between the P atoms decreases. The Young’s modulus and radial Poisson’s ratio are insensitive to the tube radius. Furthermore, the zigzag nanotubes have higher values than armchair nanotubes. In addition, we find that both zigzag and armchair PNTs show semiconducting properties with different radius. It is expected that these properties have potential applications in nanometer-sized devices design. [ABSTRACT FROM AUTHOR]

Abstract: A 3D single-wall carbon nanotube can be viewed as a 2D graphite sheet rolled into a 3D cylinder. In the study of dispersion relations of carbon nanotubes, the consistent force parameters for 2D graphite sheets have to be modified to include the curvature effect. The present paper reports a series of calculations of phonon dispersion relations for single-wall carbon armchair, zigzag nanotube in which the curvature effect has been properly treated. The symmetry of crystal vibration mode at the centre of Brillouin zone is analyzed based on our numeric results and the structure symmetry of the nanotubes. [Copyright &y& Elsevier]

Single wall carbon nanotubes (SWNTs) were synthesized by electric arc discharge method with a mixture of nickel and yttrium as catalysts. The effect of the catalyst concentration on the synthesis of SWNTs was studied. Raman spectra of SWNTs have been recorded with excitation wavelengths from 476.5 to 1064 nm. The Raman peaks of the radial breathing modes (RBM) of SWNTs were assigned. The results indicate that the diameter distribution of SWNTs is in the range of 1.2–1.6 nm, and the SWNTs with diameter 1.43 nm are in the majority. The catalyst concentrations have large effect on the yield of SWNTs and little effect on the diameter distribution of SWNTs. [ABSTRACT FROM AUTHOR]

Abstract: The phonon dispersions of single-wall BC3 nanotubes with any chirality are calculated within a symmetry-based force constant model of the lattice dynamics. Based on the non-symmorphic symmetry group of the BC3 tubes, the symmetries and number of the Raman- and infrared-active modes at Γ point of the one-dimensional Brillouin zone are given. The neighbor atom–atomic interaction force constants are recalculated by fitting them to the experimental phonon energy-dispersion curves of honeycomb BC3 sheet. The frequencies of the optically active modes are presented as the function of diameters and chiralities for BC3 tubes. The obtained phonon density-of-states spectra, phonon dispersion relations, and vibrational patterns of the zone-center phonons are presented and discussed in detail. The calculated frequencies of infrared-active modes are compared with the experimental values reported in the literature. The results provide comprehensive information about the vibrational properties of the BC3 tubes and shed light on the interpretation of Raman scattering and infrared spectroscopies. [Copyright &y& Elsevier]

• Li atoms prefer to be adsorbed at the V-site in both pure monolayer P and SWBPNT. • Compared with the outside, the inside of SWBPNT is a fast diffusion channel for Li. • As the number of Li atoms increases, they still prefer to be adsorbed inside SWBPNT. • The study suggest that SWBPNT can be used in Li-ion batteries as anode base material. Based on first principles calculations, the possibility of zigzag single-walled blue phosphorene nanotube (SWBPNT) as anode materials for high-performance lithium-ion batteries is studied. We calculate the adsorption, diffusion properties and cell voltages of lithium intercalation on the inside and outside of SWBPNT and compare them with those in carbon nanotube (CNT) and single-walled Si nanotube (SWSiNT). The results show that the inside of SWBPNT is a fast diffusion channel of lithium compared with the outside of SWBPNT. By calculating the structure parameters, adsorption energy and charge transfer, we study the adsorption of multiple lithium atoms in SWBPNT. The results show that lithium is easier to diffuse and adsorb inside the tubes, which will help to improve the lithium storage capacity of the system. Therefore, SWBPNT has great potential as anode materials for Li-ion batteries. [ABSTRACT FROM AUTHOR]