Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSelf-Collapse and Sliding of Nanotubes in a Bundle
265
0
0.0
(
0
)
Authors
Nicola Maria Pugno
Ask ChatGPT about the research
No Arabic abstract
We have discovered that the influence of the surrounding nanotubes in a bundle is similar to that of a liquid having surface tension equal to the surface energy of the nanotubes. This surprising behaviour is confirmed by the calculation of the self-collapse diameters of nanotubes in a bundle. Other systems, such as peapods, fullerites, are similarly treated, including the effect of the presence of a solvent. Finally, we have evaluated the strength and toughness of the nanotube bundle, with or without collapsed nanotubes, assuming a sliding failure.
rate research
Read More
We discovered in simulations of sliding coaxial nanotubes an unanticipated example of dynamical symmetry breaking taking place at the nanoscale. While both nanotubes are perfectly left-right symmetric and nonchiral, a nonzero angular momentum of phonon origin appears spontaneously at a series of critical sliding velocities, in correspondence with large peaks of the sliding friction. The non-linear equations governing this phenomenon resemble the rotational instability of a forced string. However, several new elements, exquisitely nano appear here, with the crucial involvement of Umklapp and of sliding nanofriction.
We study the low temperature phase behavior of hydrogen within a bundle of carbon nanotubes. Because the carbon environment weakens the attraction between molecules within the same interstitial channel (IC), the ground state of the one-dimensional (1D) system is an uncondensed gas. When the screened attractive interaction between molecules in adjacent ICs is taken into account, the hydrogen ground state is a quasi-1D liquid. The critical temperature of this system is estimated.
The so-called interlayer-sliding ferroelectricity was recently proposed as an unconventional route to pursuit electric polarity in van der Waals multi-layers, which was already experimentally confirmed in WTe$_2$ bilayer even though it is metallic. Very recently, another van der Waals system, i.e., the ZrI$_2$ bilayer, was predicted to exhibit the interlayer-sliding ferroelectricity with both in-plane and out-of-plane polarizations [Phys. Rev. B textbf{103}, 165420 (2021)]. Here the ZrI$_2$ bulk is studied, which owns two competitive phases ($alpha$ textit{vs} $beta$), both of which are derived from the common parent $s$-phase. The $beta$-ZrI$_2$ owns a considerable out-of-plane polarization ($0.39$ $mu$C/cm$^2$), while its in-plane component is fully compensated. Their proximate energies provide the opportunity to tune the ground state phase by moderate hydrostatic pressure and uniaxial strain. Furthermore, the negative longitudinal piezoelectricity in $beta$-ZrI$_2$ is dominantly contributed by the enhanced dipole of ZrI$_2$ layers as a unique characteristic of interlayer-sliding ferroelectricity, which is different from many other layered ferroelectrics with negative longitudinal piezoelectricity like CuInP$_2$S$_6$.
The generalized tight-binding model, based on the subenvelope functions of distinct sublattices, is developed to investigate the magnetic quantization in sliding bilayer graphenes. The relative shift of two graphene layers induces a dramatic transformation between the Dirac-cone structure and the parabolic band structure, and thus leads to drastic changes of Landau levels (LLs) in the spatial symmetry, initial formation energy, intergroup anti-crossing, state degeneracy and semiconductor-metal transition. There exist three kinds of LLs, i.e., well-behaved, perturbed and undefined LLs, which are characterized by a specific mode, a main mode plus side modes, and a disordered mode, respectively. Such LLs are clearly revealed in diverse magneto-optical selection rules. Specially, the undefined LLs frequently exhibit intergroup anti-crossings in the field-dependent energy spectra, and show a large number of absorption peaks without optical selection rules.
A new class of tetragonally symmetric 2D octagonal family of monolayers (o-MLs) has emerged recently and demands understanding at the fundamental level. o-MLs of metal nitride and carbide family (BN, AlN, GaN, GeC, SiC) along with C and BP are computationally designed and their stability and electronic structure are investigated. These binary o-MLs show mixed ionic and covalent bonding with the hybridized p states dominating the electronic structure around the Fermi level. Geometric and structural similarity of o-C and o-BN has been exploited to form patterned hybrid o-MLs ranging from metallic to insulating phases. Stacking of zigzag buckled o-MLs results in stable body centered tetragonal (bct)-bulk phase that is suitable for most materials from group IV, III-V and II-VI. Vertically cut chunks of o-BN and o-C bulk or stacking of o-rings, unlike rolling of hexagonal (h)-ML, provide a plausible way to form very thin o-nanotubes (o-NT). Confined and bulk structures formed with an octagonal motif are of fundamental importance to understand the underlying science and for technological applications.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
