1,436 research outputs found
A Brief Review on Syntheses, Structures and Applications of Nanoscrolls
Nanoscrolls are papyrus-like nanostructures which present unique properties
due to their open ended morphology. These properties can be exploited in a
plethora of technological applications, leading to the design of novel and
interesting devices. During the past decade, significant advances in the
synthesis and characterization of these structures have been made, but many
challenges still remain. In this mini review we provide an overview on their
history, experimental synthesis methods, basic properties and application
perspectives
One-dimensional Silicon and Germanium Nanostructures With No Carbon Analogues
In this work we report new silicon and germanium tubular nanostructures with
no corresponding stable carbon analogues. The electronic and mechanical
properties of these new tubes were investigated through ab initio methods. Our
results show that the structures have lower energy than their corresponding
nanoribbon structures and are stable up to high temperatures (500 and 1000 K,
for silicon and germanium tubes, respectively). Both tubes are semiconducting
with small indirect band gaps, which can be significantly altered by both
compressive and tensile strains. Large bandgap variations of almost 50% were
observed for strain rates as small as 3%, suggesting possible applications in
sensor devices. They also present high Young's modulus values (0.25 and 0.15
TPa, respectively). TEM images were simulated to help the identification of
these new structures
Site-dependent hydrogenation on graphdiyne
Graphene is one of the most important materials in science today due to its
unique and remarkable electronic, thermal and mechanical properties. However in
its pristine state, graphene is a gapless semiconductor, what limits its use in
transistor electronics. In part due to the revolution created by graphene in
materials science, there is a renewed interest in other possible graphene-like
two-dimensional structures. Examples of these structures are graphynes and
graphdiynes, which are two-dimensional structures, composed of carbon atoms in
sp2 and sp-hybridized states. Graphdiynes (benzenoid rings connecting two
acetylenic groups) were recently synthesized and some of them are intrinsically
nonzero gap systems. These systems can be easily hydrogenated and the relative
level of hydrogenation can be used to tune the band gap values. We have
investigated, using fully reactive molecular dynamics (ReaxFF), the structural
and dynamics aspects of the hydrogenation mechanisms of graphdiyne membranes.
Our results showed that the hydrogen bindings have different atom incorporation
rates and that the hydrogenation patterns change in time in a very complex way.
The formation of correlated domains reported to hydrogenated graphene is no
longer observed in graphdiyne cases.Comment: Submitted to Carbo
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