88 research outputs found
Mechanical Properties and Fracture Dynamics of Silicene Membranes
As graphene became one of the most important materials today, there is a
renewed interest on others similar structures. One example is silicene, the
silicon analogue of graphene. It share some the remarkable graphene properties,
such as the Dirac cone, but presents some distinct ones, such as a pronounced
structural buckling. We have investigated, through density functional based
tight-binding (DFTB), as well as reactive molecular dynamics (using ReaxFF),
the mechanical properties of suspended single-layer silicene. We calculated the
elastic constants, analyzed the fracture patterns and edge reconstructions. We
also addressed the stress distributions, unbuckling mechanisms and the fracture
dependence on the temperature. We analysed the differences due to distinct edge
morphologies, namely zigzag and armchair
Curved Graphene Nanoribbons: Structure and Dynamics of Carbon Nanobelts
Carbon nanoribbons (CNRs) are graphene (planar) structures with large aspect
ratio. Carbon nanobelts (CNBs) are small graphene nanoribbons rolled up into
spiral-like structures, i. e., carbon nanoscrolls (CNSs) with large aspect
ratio. In this work we investigated the energetics and dynamical aspects of
CNBs formed from rolling up CNRs. We have carried out molecular dynamics
simulations using reactive empirical bond-order potentials. Our results show
that similarly to CNSs, CNBs formation is dominated by two major energy
contribution, the increase in the elastic energy due to the bending of the
initial planar configuration (decreasing structural stability) and the
energetic gain due to van der Waals interactions of the overlapping surface of
the rolled layers (increasing structural stability). Beyond a critical diameter
value these scrolled structures can be even more stable (in terms of energy)
than their equivalent planar configurations. In contrast to CNSs that require
energy assisted processes (sonication, chemical reactions, etc.) to be formed,
CNBs can be spontaneously formed from low temperature driven processes. Long
CNBs (length of 30.0 nm) tend to exhibit self-folded racket-like
conformations with formation dynamics very similar to the one observed for long
carbon nanotubes. Shorter CNBs will be more likely to form perfect scrolled
structures. Possible synthetic routes to fabricate CNBs from graphene membranes
are also addressed
Dynamical Aspects Of The Unzipping Of Multiwalled Boron Nitride Nanotubes.
Boron nitride nanoribbons (BNNRs) exhibit very interesting magnetic properties, which could be very useful in the development of spintronic based devices. One possible route to obtain BNNRs is through the unzipping of boron nitride nanotubes (BNNTs), which have been already experimentally realized. In this work, different aspects of the unzipping process of BNNTs were investigated through fully atomistic molecular dynamics simulations using a classical reactive force field (ReaxFF). We investigated multiwalled BNNTs of different diameters and chiralities. Our results show that chirality plays a very important role in the unzipping process, as well as the interlayer coupling. These combined aspects significantly change the fracturing patterns and several other features of the unzipping processes in comparison to the ones observed for carbon nanotubes. Also, similar to carbon nanotubes, defective BNNTs can create regions of very high curvature which can act as a path to the unzipping process.1519147-5
The effect of adding boron in solidification microstructure of dilute iron-carbon alloy as assessed by phase-field modeling
Eating patterns in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil): an exploratory analysis
InfluĂȘncia da palha e da simulação de chuva sobre a eficĂĄcia da mistura formulada clomazone + hexazinone no controle de plantas daninhas em ĂĄrea de cana-crua
Efeito da chuva na eficiĂȘncia de herbicidas aplicados em pĂłs-emergĂȘncia sobre corda-de-viola
Suscetibilidade diferencial de espécies convolvulåceas ao flumioxazin determinada através de curvas de dose-resposta
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