41.
Fonseca, AD; Malta, CP; Galvao, DS
Elastic Properties of Normal and Binormal Helical Nanowires Proceedings
Warrendale, Pa.; Materials Research Society; 1999, vol. 963, 2007.
@proceedings{fonseca2007elastic,
title = {Elastic Properties of Normal and Binormal Helical Nanowires},
author = {Fonseca, AD and Malta, CP and Galvao, DS},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8026852},
year = {2007},
date = {2007-01-01},
journal = {MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS},
volume = {963},
pages = {88},
publisher = {Warrendale, Pa.; Materials Research Society; 1999},
abstract = {A helical nanowire can be defined as being a nanoscopic rod whose axis follows a helical curve in space. In the case of a nanowire with asymmetric cross section, the helical nanostructure can be classified as normal or binormal helix, according to the orientation of the cross section with respect to the helical axis of the structure. In this work, we present a simple model to study the elastic properties of a helical nanowire with asymmetric cross section. We use the framework of the Kirchhoff rod model to obtain an expression relating the Hooke's constant, h, of normal and binormal nanohelices to their geometric features. We also obtain the Young's modulus values. These relations can be used by experimentalists to evaluate the elastic properties of helical nanostructures. We showed that the Hooke's constant of a normal nanohelix is higher than that of a binormal one. We illustrate our results using experimentally obtained nanohelices reported in the literature.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
A helical nanowire can be defined as being a nanoscopic rod whose axis follows a helical curve in space. In the case of a nanowire with asymmetric cross section, the helical nanostructure can be classified as normal or binormal helix, according to the orientation of the cross section with respect to the helical axis of the structure. In this work, we present a simple model to study the elastic properties of a helical nanowire with asymmetric cross section. We use the framework of the Kirchhoff rod model to obtain an expression relating the Hooke's constant, h, of normal and binormal nanohelices to their geometric features. We also obtain the Young's modulus values. These relations can be used by experimentalists to evaluate the elastic properties of helical nanostructures. We showed that the Hooke's constant of a normal nanohelix is higher than that of a binormal one. We illustrate our results using experimentally obtained nanohelices reported in the literature.
42.
Coluci, VR; Dantas, SO; Jorio, A; Galvao, DS
Electronic and Mechanical Properties of Super Carbon Nanotube Networks Proceedings
Warrendale, Pa.; Materials Research Society; 1999, vol. 963, 2007.
@proceedings{coluci2007electronic,
title = {Electronic and Mechanical Properties of Super Carbon Nanotube Networks},
author = {Coluci, VR and Dantas, SO and Jorio, A and Galvao, DS},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8026810&fulltextType=RA&fileId=S1946427400054014},
year = {2007},
date = {2007-01-01},
journal = {MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS},
volume = {963},
pages = {1},
publisher = {Warrendale, Pa.; Materials Research Society; 1999},
abstract = {Eletronic and mechanical properties of ordered carbon nanotube networks are studied using molecular dynamics simulations and tight-binding calculations. These networks are formed by single walled carbon nanotubes (SWNT) regularly connected by junctions. The use of different types of junctions (“Y”-, “X”-like junctions, for example) allows the construction of networks with different symmetries. These networks can be very flexible and the elastic deformation was associated with two main deformation mechanisms (bending and stretching ) of the constituents SWNTs. Rolling up the networks, “super” carbon nanotubes can be constructed. These super-tubes share some of the main electronic features of the SWNT which form them but important changes are predicted (e.g. reduction of bandgap value). Simulations of their deformations under tensile stress have revealed that the super-tubes are softer than the corresponding SWNT and that their rupture occur in higher strain values.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Eletronic and mechanical properties of ordered carbon nanotube networks are studied using molecular dynamics simulations and tight-binding calculations. These networks are formed by single walled carbon nanotubes (SWNT) regularly connected by junctions. The use of different types of junctions (“Y”-, “X”-like junctions, for example) allows the construction of networks with different symmetries. These networks can be very flexible and the elastic deformation was associated with two main deformation mechanisms (bending and stretching ) of the constituents SWNTs. Rolling up the networks, “super” carbon nanotubes can be constructed. These super-tubes share some of the main electronic features of the SWNT which form them but important changes are predicted (e.g. reduction of bandgap value). Simulations of their deformations under tensile stress have revealed that the super-tubes are softer than the corresponding SWNT and that their rupture occur in higher strain values.
43.
Fonseca, Alexandre F; Malta, CP; Galvao, DS
Is it possible to grow amorphous normal nanosprings? Journal Article
In: Nanotechnology, vol. 18, no. 43, pp. 435606, 2007.
@article{fonseca2007possible,
title = {Is it possible to grow amorphous normal nanosprings?},
author = {Fonseca, Alexandre F and Malta, CP and Galvao, DS},
url = {http://iopscience.iop.org/0957-4484/18/43/435606},
year = {2007},
date = {2007-01-01},
journal = {Nanotechnology},
volume = {18},
number = {43},
pages = {435606},
publisher = {IOP Publishing},
abstract = {Nanosprings have been objects of intense investigations in recent years. They can be classified as normal or binormal depending on the geometry of their cross-section. As normal amorphous nanosprings have not yet been observed experimentally, we have decided to investigate this matter. We discuss the shape of the catalyst in terms of the cross-sectional shape of the nanospring and show that, within the vapor–liquid–solid model, the growth of amorphous binormal nanosprings is energetically favored.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nanosprings have been objects of intense investigations in recent years. They can be classified as normal or binormal depending on the geometry of their cross-section. As normal amorphous nanosprings have not yet been observed experimentally, we have decided to investigate this matter. We discuss the shape of the catalyst in terms of the cross-sectional shape of the nanospring and show that, within the vapor–liquid–solid model, the growth of amorphous binormal nanosprings is energetically favored.
44.
Coluci, VR; Dantas, SO; Jorio, A; Galvao, DS
Mechanical properties of carbon nanotube networks by molecular mechanics and impact molecular dynamics calculations Journal Article
In: Physical Review B, vol. 75, no. 7, pp. 075417, 2007.
@article{coluci2007mechanical,
title = {Mechanical properties of carbon nanotube networks by molecular mechanics and impact molecular dynamics calculations},
author = {Coluci, VR and Dantas, SO and Jorio, A and Galvao, DS},
url = {http://journals.aps.org/prb/abstract/10.1103/PhysRevB.75.075417},
year = {2007},
date = {2007-01-01},
journal = {Physical Review B},
volume = {75},
number = {7},
pages = {075417},
publisher = {APS},
abstract = {We report a theoretical investigation of the mechanical properties of idealized networks formed by single-walled carbon nanotubes showing crossbar and hexagonal architectures. The study was performed by using molecular mechanics calculations and impact dynamics simulations based on bond-order empirical potential. The studied networks were predicted to have elasticity modulus of ∼10–100GPa and bulk modulus of ∼10GPa. The results show a transition from high to moderate flexibility during the deformation stages. This behavior was associated with the existence of two deformation mechanisms presented by the network related to the nanotube stretching and junction bending processes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report a theoretical investigation of the mechanical properties of idealized networks formed by single-walled carbon nanotubes showing crossbar and hexagonal architectures. The study was performed by using molecular mechanics calculations and impact dynamics simulations based on bond-order empirical potential. The studied networks were predicted to have elasticity modulus of ∼10–100GPa and bulk modulus of ∼10GPa. The results show a transition from high to moderate flexibility during the deformation stages. This behavior was associated with the existence of two deformation mechanisms presented by the network related to the nanotube stretching and junction bending processes.
45.
Pugno, Nicola; Coluci, V; Galvao, DS
Nanotube-or graphene-based nanoarmors Book Chapter
In: Computational & Experimental Analysis of Damaged Materials, pp. 145-154 , 2007.
@inbook{pugno2007nanotube,
title = {Nanotube-or graphene-based nanoarmors},
author = {Pugno, Nicola and Coluci, V and Galvao, DS},
url = {http://www.ing.unitn.it/~pugno/NP_PDF/IV/5-COLUCI07.pdf},
year = {2007},
date = {2007-01-01},
booktitle = {Computational & Experimental Analysis of Damaged Materials},
pages = {145-154 },
abstract = { In this paper, nanoimpacts on hexagonal or
crossbar nanotube networks as well as on graphene
sheets are investigated by elasticity and finite
kinematics or impact molecular dynamic simulations.
A transition from bending to stretching by increasing
the impact kinetic energy of the nanoprojectile is
clearly observed. The analysis suggests that the
investigated nanotextures are ideal for designing
futuristic nanoarmors. },
keywords = {},
pubstate = {published},
tppubtype = {inbook}
}
In this paper, nanoimpacts on hexagonal or
crossbar nanotube networks as well as on graphene
sheets are investigated by elasticity and finite
kinematics or impact molecular dynamic simulations.
A transition from bending to stretching by increasing
the impact kinetic energy of the nanoprojectile is
clearly observed. The analysis suggests that the
investigated nanotextures are ideal for designing
futuristic nanoarmors.
crossbar nanotube networks as well as on graphene
sheets are investigated by elasticity and finite
kinematics or impact molecular dynamic simulations.
A transition from bending to stretching by increasing
the impact kinetic energy of the nanoprojectile is
clearly observed. The analysis suggests that the
investigated nanotextures are ideal for designing
futuristic nanoarmors.
46.
Braga, Scheila Furtado; Galvao, Douglas Soares
Molecular dynamics simulation of single wall carbon nanotubes polymerization under compression Journal Article
In: Journal of Computational Chemistry, vol. 28, no. 10, pp. 1724–1734, 2007.
@article{braga2007molecular,
title = {Molecular dynamics simulation of single wall carbon nanotubes polymerization under compression},
author = {Braga, Scheila Furtado and Galvao, Douglas Soares},
url = {http://onlinelibrary.wiley.com/store/10.1002/jcc.20684/asset/20684_ftp.pdf?v=1&t=i52l5iyb&s=94cda082eed01cd61890fffe50aad5e26cdda7d1},
year = {2007},
date = {2007-01-01},
journal = {Journal of Computational Chemistry},
volume = {28},
number = {10},
pages = {1724--1734},
publisher = {Wiley Subscription Services, Inc., A Wiley Company},
abstract = {Single wall carbon nanotubes (SWCNTs) often aggregate into bundles of hundreds of weakly interacting
tubes. Their cross-polymerization opens new possibilities for the creation of new super-hard materials. New mechanical
and electronic properties are expected from these condensed structures, as well as novel potential applications. Previous
theoretical results presented geometric modifications involving changes in the radial section of the compressed tubes
as the explanation to the experimental measurements of structural changes during tube compression. We report here
results from molecular dynamics simulations of the SWCNTs polymerization for small diameter arm chair tubes under
compression. Hydrostatic and piston-type compression of SWCNTs have been simulated for different temperatures and
rates of compression. Our results indicate that large diameter tubes (10,10) are unlike to polymerize while small diameter
ones (around 5 Å) polymerize even at room temperature. Other interesting results are the observation of the appearance
of spontaneous scroll-like structures and also the so-called tubulane motifs, which were predicted in the literature more
than a decade ago},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Single wall carbon nanotubes (SWCNTs) often aggregate into bundles of hundreds of weakly interacting
tubes. Their cross-polymerization opens new possibilities for the creation of new super-hard materials. New mechanical
and electronic properties are expected from these condensed structures, as well as novel potential applications. Previous
theoretical results presented geometric modifications involving changes in the radial section of the compressed tubes
as the explanation to the experimental measurements of structural changes during tube compression. We report here
results from molecular dynamics simulations of the SWCNTs polymerization for small diameter arm chair tubes under
compression. Hydrostatic and piston-type compression of SWCNTs have been simulated for different temperatures and
rates of compression. Our results indicate that large diameter tubes (10,10) are unlike to polymerize while small diameter
ones (around 5 Å) polymerize even at room temperature. Other interesting results are the observation of the appearance
of spontaneous scroll-like structures and also the so-called tubulane motifs, which were predicted in the literature more
than a decade ago
tubes. Their cross-polymerization opens new possibilities for the creation of new super-hard materials. New mechanical
and electronic properties are expected from these condensed structures, as well as novel potential applications. Previous
theoretical results presented geometric modifications involving changes in the radial section of the compressed tubes
as the explanation to the experimental measurements of structural changes during tube compression. We report here
results from molecular dynamics simulations of the SWCNTs polymerization for small diameter arm chair tubes under
compression. Hydrostatic and piston-type compression of SWCNTs have been simulated for different temperatures and
rates of compression. Our results indicate that large diameter tubes (10,10) are unlike to polymerize while small diameter
ones (around 5 Å) polymerize even at room temperature. Other interesting results are the observation of the appearance
of spontaneous scroll-like structures and also the so-called tubulane motifs, which were predicted in the literature more
than a decade ago
47.
Coluci, Vitor R; Dantas, Socrates O; Jorio, Ado; Galvao, Douglas S.
Electronic and Mechanical Properties of Super Carbon Nanotube Networks Proceedings
Cambridge University Press, vol. 963, 2006.
@proceedings{coluci2006electronic,
title = {Electronic and Mechanical Properties of Super Carbon Nanotube Networks},
author = {Coluci, Vitor R and Dantas, Socrates O and Jorio, Ado and Galvao, Douglas S.},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8026810&fileId=S1946427400054014},
year = {2006},
date = {2006-01-01},
journal = {MRS Proceedings},
volume = {963},
pages = {0963--Q15},
publisher = {Cambridge University Press},
abstract = {Eletronic and mechanical properties of ordered carbon nanotube networks are studied using molecular dynamics simulations and tight-binding calculations. These networks are formed by single walled carbon nanotubes (SWNT) regularly connected by junctions. The use of different types of junctions (“Y”-, “X”-like junctions, for example) allows the construction of networks with different symmetries. These networks can be very flexible and the elastic deformation was associated with two main deformation mechanisms (bending and stretching ) of the constituents SWNTs. Rolling up the networks, “super” carbon nanotubes can be constructed. These super-tubes share some of the main electronic features of the SWNT which form them but important changes are predicted (e.g. reduction of bandgap value). Simulations of their deformations under tensile stress have revealed that the super-tubes are softer than the corresponding SWNT and that their rupture occur in higher strain values.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Eletronic and mechanical properties of ordered carbon nanotube networks are studied using molecular dynamics simulations and tight-binding calculations. These networks are formed by single walled carbon nanotubes (SWNT) regularly connected by junctions. The use of different types of junctions (“Y”-, “X”-like junctions, for example) allows the construction of networks with different symmetries. These networks can be very flexible and the elastic deformation was associated with two main deformation mechanisms (bending and stretching ) of the constituents SWNTs. Rolling up the networks, “super” carbon nanotubes can be constructed. These super-tubes share some of the main electronic features of the SWNT which form them but important changes are predicted (e.g. reduction of bandgap value). Simulations of their deformations under tensile stress have revealed that the super-tubes are softer than the corresponding SWNT and that their rupture occur in higher strain values.
48.
Coluci, Vitor R; Galvao, Douglas S; Jorio, A
Geometric and electronic structure of carbon nanotube networks:'super'-carbon nanotubes Journal Article
In: Nanotechnology, vol. 17, no. 3, pp. 617, 2006.
@article{coluci2006geometric,
title = {Geometric and electronic structure of carbon nanotube networks:'super'-carbon nanotubes},
author = {Coluci, Vitor R and Galvao, Douglas S and Jorio, A},
url = {http://iopscience.iop.org/0957-4484/17/3/001},
year = {2006},
date = {2006-01-01},
journal = {Nanotechnology},
volume = {17},
number = {3},
pages = {617},
publisher = {IoP Publishing},
abstract = {Structures of the so-called super-carbon nanotubes are proposed. These structures are built from single walled carbon nanotubes connected by Y-like junctions forming a 'super'-sheet that is then rolled into a seamless cylinder. Such a procedure can be repeated several times, generating a fractal structure. This procedure is not limited to carbon nanotubes, and can be easily modified for application to other systems. Tight binding total energy and density of states calculations showed that the 'super'-sheets and tubes are stable and predicted to present metallic and semiconducting behaviour.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Structures of the so-called super-carbon nanotubes are proposed. These structures are built from single walled carbon nanotubes connected by Y-like junctions forming a 'super'-sheet that is then rolled into a seamless cylinder. Such a procedure can be repeated several times, generating a fractal structure. This procedure is not limited to carbon nanotubes, and can be easily modified for application to other systems. Tight binding total energy and density of states calculations showed that the 'super'-sheets and tubes are stable and predicted to present metallic and semiconducting behaviour.
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