1.
Rodrigo Prioli Clara M Almeida, Benjamin Fragneaud
Giant and Tunable Anisotropy of Nanoscale Friction in Graphene Journal Article
In: Nature Scientific Reports, vol. 6, pp. 31569, 2016.
@article{Almeida2016,
title = {Giant and Tunable Anisotropy of Nanoscale Friction in Graphene},
author = {Clara M Almeida, Rodrigo Prioli, Benjamin Fragneaud, Luiz Gustavo Cançado, Ricardo Paupitz, Douglas S Galvão, Marcelo De Cicco, Marcos G Menezes, Carlos A Achete, Rodrigo B Capaz},
url = {http://www-nature-com.ez88.periodicos.capes.gov.br/articles/srep31569},
doi = {10.1038/srep31569},
year = {2016},
date = {2016-07-18},
journal = {Nature Scientific Reports},
volume = {6},
pages = {31569},
abstract = {The nanoscale friction between an atomic force microscopy tip and graphene is investigated using friction force microscopy (FFM). During the tip movement, friction forces are observed to increase and then saturate in a highly anisotropic manner. As a result, the friction forces in graphene are highly dependent on the scanning direction: under some conditions, the energy dissipated along the armchair direction can be 80% higher than along the zigzag direction. In comparison, for highly-oriented pyrolitic graphite (HOPG), the friction anisotropy between armchair and zigzag directions is only 15%. This giant friction anisotropy in graphene results from anisotropies in the amplitudes of flexural deformations of the graphene sheet driven by the tip movement, not present in HOPG. The effect can be seen as a novel manifestation of the classical phenomenon of Euler buckling at the nanoscale, which provides the non-linear ingredients that amplify friction anisotropy. Simulations based on a novel version of the 2D Tomlinson model (modified to include the effects of flexural deformations), as well as fully atomistic molecular dynamics simulations and first-principles density-functional theory (DFT) calculations, are able to reproduce and explain the experimental observations.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The nanoscale friction between an atomic force microscopy tip and graphene is investigated using friction force microscopy (FFM). During the tip movement, friction forces are observed to increase and then saturate in a highly anisotropic manner. As a result, the friction forces in graphene are highly dependent on the scanning direction: under some conditions, the energy dissipated along the armchair direction can be 80% higher than along the zigzag direction. In comparison, for highly-oriented pyrolitic graphite (HOPG), the friction anisotropy between armchair and zigzag directions is only 15%. This giant friction anisotropy in graphene results from anisotropies in the amplitudes of flexural deformations of the graphene sheet driven by the tip movement, not present in HOPG. The effect can be seen as a novel manifestation of the classical phenomenon of Euler buckling at the nanoscale, which provides the non-linear ingredients that amplify friction anisotropy. Simulations based on a novel version of the 2D Tomlinson model (modified to include the effects of flexural deformations), as well as fully atomistic molecular dynamics simulations and first-principles density-functional theory (DFT) calculations, are able to reproduce and explain the experimental observations.
2.
dos Santos, Ricardo P; Machado, Leonardo D; Legoas, Sergio B; Galvao, Douglas S
Tribological Properties of Graphene and Boron-Nitride Layers: A Fully Atomistic Molecular Dynamics Study Proceedings
Cambridge University Press, vol. 1407, 2012.
@proceedings{dos2012tribological,
title = {Tribological Properties of Graphene and Boron-Nitride Layers: A Fully Atomistic Molecular Dynamics Study},
author = {dos Santos, Ricardo P and Machado, Leonardo D and Legoas, Sergio B and Galvao, Douglas S},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8537106&fileId=S1946427412007063},
year = {2012},
date = {2012-01-01},
journal = {MRS Proceedings},
volume = {1407},
pages = {mrsf11--1407},
publisher = {Cambridge University Press},
abstract = {Graphene has been one of the most important subjects in materials science in the last years. Recently, the frictional characteristics of atomically thin sheets were experimentally investigated using atomic force microscopy (AFM). A new mechanism to explain the enhanced friction for these materials, based on elastic compliance has been proposed. Here, we have investigated the tribological properties of graphene and boron-nitride (single and multi-layers) membranes using fully atomistic molecular dynamics simulations. These simulations were carried out using classical force fields, as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. The used structural models contain typically hundreds of thousands of atoms. In order to mimic the experimental conditions, an artificial AFM tip was moved over the membranes and the tribological characteristics determined in terms of forces and energies. Our results are in good agreement with the available experimental data. They show that the observed enhanced tribological properties can be explained in terms of out-of-plane geometrical distortions and elastic waves propagation. They validate the general features of the model proposed by Lee et al. (Science 328, 76 (2010).},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Graphene has been one of the most important subjects in materials science in the last years. Recently, the frictional characteristics of atomically thin sheets were experimentally investigated using atomic force microscopy (AFM). A new mechanism to explain the enhanced friction for these materials, based on elastic compliance has been proposed. Here, we have investigated the tribological properties of graphene and boron-nitride (single and multi-layers) membranes using fully atomistic molecular dynamics simulations. These simulations were carried out using classical force fields, as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. The used structural models contain typically hundreds of thousands of atoms. In order to mimic the experimental conditions, an artificial AFM tip was moved over the membranes and the tribological characteristics determined in terms of forces and energies. Our results are in good agreement with the available experimental data. They show that the observed enhanced tribological properties can be explained in terms of out-of-plane geometrical distortions and elastic waves propagation. They validate the general features of the model proposed by Lee et al. (Science 328, 76 (2010).
3.
Nakabayashi, D; Ugarte, D; Moreau, ALD; Coluci, VR; Galvao, DS; Cotta, MA
Carbon nanotubes as R-bars of high aspect ratio composite nanotools Technical Report
2008.
@techreport{nakabayashi2008carbonb,
title = {Carbon nanotubes as R-bars of high aspect ratio composite nanotools},
author = {Nakabayashi, D and Ugarte, D and Moreau, ALD and Coluci, VR and Galvao, DS and Cotta, MA},
url = {http://lnls.cnpem.br/ar2008/},
year = {2008},
date = {2008-01-01},
abstract = {Nano technology requires the development of nano scale tools to manipulate nano systems. From the point of view of materials science, this represents a serious challenge, because nano tools must meet a series of stringent requirements of shape (size, aspect ratio), mechanical, magnetic and electrical properties. We have developed long and narrow carbon-carbon composite nano tips using carbon nanotubes covered by an amorphous carbon shell; the very small nano tube tip remained uncoated to preserve apex size. This configuration renders the system stiffer and allows for the control of flexibility and vibrations. In addition, we have maintained the important nano tube properties of size, strength and resilience. Nano manipulation experiments in situ in a high resolution scanning electron microscope were used to optimize the tips behavior and molecular dynamics simulations were used to study the mechanical response. Finally, we performed a practical application in atomic force microscopy. Composite tips yielded excellent image resolution and showed remarkable wear resistance (no degradation of image quality after acquiring several hundred images). },
keywords = {},
pubstate = {published},
tppubtype = {techreport}
}
Nano technology requires the development of nano scale tools to manipulate nano systems. From the point of view of materials science, this represents a serious challenge, because nano tools must meet a series of stringent requirements of shape (size, aspect ratio), mechanical, magnetic and electrical properties. We have developed long and narrow carbon-carbon composite nano tips using carbon nanotubes covered by an amorphous carbon shell; the very small nano tube tip remained uncoated to preserve apex size. This configuration renders the system stiffer and allows for the control of flexibility and vibrations. In addition, we have maintained the important nano tube properties of size, strength and resilience. Nano manipulation experiments in situ in a high resolution scanning electron microscope were used to optimize the tips behavior and molecular dynamics simulations were used to study the mechanical response. Finally, we performed a practical application in atomic force microscopy. Composite tips yielded excellent image resolution and showed remarkable wear resistance (no degradation of image quality after acquiring several hundred images).
4.
Nakabayashi, D; Moreau, ALD; Coluci, VR; Galvao, DS; Cotta, MA; Ugarte, D
Carbon nanotubes as reinforcement elements of composite nanotools Journal Article
In: Nano letters, vol. 8, no. 3, pp. 842–847, 2008.
@article{nakabayashi2008carbon,
title = {Carbon nanotubes as reinforcement elements of composite nanotools},
author = {Nakabayashi, D and Moreau, ALD and Coluci, VR and Galvao, DS and Cotta, MA and Ugarte, D},
url = {http://pubs.acs.org/doi/abs/10.1021/nl0729633},
year = {2008},
date = {2008-01-01},
journal = {Nano letters},
volume = {8},
number = {3},
pages = {842--847},
publisher = {American Chemical Society},
abstract = {Nanotechnology is stimulating the development of nanomanipulators, including tips to interact with individual nanosystems. Fabricating nanotips fulfilling the requirements of shape (size, aspect ratio), mechanical, magnetic, and electrical properties is a material science challenge. Here, we report the generation of reinforced carbon−carbon composite nanotools using a nanotube (CNTs) covered by an amorphous carbon matrix (shell); the CNT tip protruded and remained uncoated to preserve apex size. Unsuitable properties such as flexibility and vibration could be controlled without deteriorating the CNT size, strength, and resilience. Nanomanipulation experiments and molecular dynamics simulations have been used to study the mechanical response of these composite beams under bending efforts. AFM probes based on these C−C composite high aspect ratio tips generated excellent image resolution and showed no degradation after acquiring several hundred (400) images.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nanotechnology is stimulating the development of nanomanipulators, including tips to interact with individual nanosystems. Fabricating nanotips fulfilling the requirements of shape (size, aspect ratio), mechanical, magnetic, and electrical properties is a material science challenge. Here, we report the generation of reinforced carbon−carbon composite nanotools using a nanotube (CNTs) covered by an amorphous carbon matrix (shell); the CNT tip protruded and remained uncoated to preserve apex size. Unsuitable properties such as flexibility and vibration could be controlled without deteriorating the CNT size, strength, and resilience. Nanomanipulation experiments and molecular dynamics simulations have been used to study the mechanical response of these composite beams under bending efforts. AFM probes based on these C−C composite high aspect ratio tips generated excellent image resolution and showed no degradation after acquiring several hundred (400) images.
5.
Legoas, Sergio B; Giro, Ronaldo; Galvao, Douglas S
Molecular dynamics simulations of C6) nanobearings Journal Article
In: Chemical physics letters, vol. 386, no. 4, pp. 425–429, 2004.
@article{legoas2004molecular,
title = {Molecular dynamics simulations of C6) nanobearings},
author = {Legoas, Sergio B and Giro, Ronaldo and Galvao, Douglas S},
url = {http://www.sciencedirect.com/science/article/pii/S000926140400168X},
year = {2004},
date = {2004-01-01},
journal = {Chemical physics letters},
volume = {386},
number = {4},
pages = {425--429},
publisher = {Elsevier},
abstract = {Recently was reported an ultra-lubricated system based on C60 molecules deposited over graphite layers. In that work a stick-slip rolling model for C60 molecules was proposed to explain the observed ultra-low friction force. In this Letter, we report the first molecular dynamics studies for these systems. Our results show that the AB stacking is not observed and the main experimental features can be explained without invoking stick-slip motions.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recently was reported an ultra-lubricated system based on C60 molecules deposited over graphite layers. In that work a stick-slip rolling model for C60 molecules was proposed to explain the observed ultra-low friction force. In this Letter, we report the first molecular dynamics studies for these systems. Our results show that the AB stacking is not observed and the main experimental features can be explained without invoking stick-slip motions.
2016
5.
Rodrigo Prioli Clara M Almeida, Benjamin Fragneaud
Giant and Tunable Anisotropy of Nanoscale Friction in Graphene Journal Article
In: Nature Scientific Reports, vol. 6, pp. 31569, 2016.
Abstract | Links | BibTeX | Tags: DFT, Graphene, Molecular Dynamics, Tribology
@article{Almeida2016,
title = {Giant and Tunable Anisotropy of Nanoscale Friction in Graphene},
author = {Clara M Almeida, Rodrigo Prioli, Benjamin Fragneaud, Luiz Gustavo Cançado, Ricardo Paupitz, Douglas S Galvão, Marcelo De Cicco, Marcos G Menezes, Carlos A Achete, Rodrigo B Capaz},
url = {http://www-nature-com.ez88.periodicos.capes.gov.br/articles/srep31569},
doi = {10.1038/srep31569},
year = {2016},
date = {2016-07-18},
journal = {Nature Scientific Reports},
volume = {6},
pages = {31569},
abstract = {The nanoscale friction between an atomic force microscopy tip and graphene is investigated using friction force microscopy (FFM). During the tip movement, friction forces are observed to increase and then saturate in a highly anisotropic manner. As a result, the friction forces in graphene are highly dependent on the scanning direction: under some conditions, the energy dissipated along the armchair direction can be 80% higher than along the zigzag direction. In comparison, for highly-oriented pyrolitic graphite (HOPG), the friction anisotropy between armchair and zigzag directions is only 15%. This giant friction anisotropy in graphene results from anisotropies in the amplitudes of flexural deformations of the graphene sheet driven by the tip movement, not present in HOPG. The effect can be seen as a novel manifestation of the classical phenomenon of Euler buckling at the nanoscale, which provides the non-linear ingredients that amplify friction anisotropy. Simulations based on a novel version of the 2D Tomlinson model (modified to include the effects of flexural deformations), as well as fully atomistic molecular dynamics simulations and first-principles density-functional theory (DFT) calculations, are able to reproduce and explain the experimental observations.
},
keywords = {DFT, Graphene, Molecular Dynamics, Tribology},
pubstate = {published},
tppubtype = {article}
}
The nanoscale friction between an atomic force microscopy tip and graphene is investigated using friction force microscopy (FFM). During the tip movement, friction forces are observed to increase and then saturate in a highly anisotropic manner. As a result, the friction forces in graphene are highly dependent on the scanning direction: under some conditions, the energy dissipated along the armchair direction can be 80% higher than along the zigzag direction. In comparison, for highly-oriented pyrolitic graphite (HOPG), the friction anisotropy between armchair and zigzag directions is only 15%. This giant friction anisotropy in graphene results from anisotropies in the amplitudes of flexural deformations of the graphene sheet driven by the tip movement, not present in HOPG. The effect can be seen as a novel manifestation of the classical phenomenon of Euler buckling at the nanoscale, which provides the non-linear ingredients that amplify friction anisotropy. Simulations based on a novel version of the 2D Tomlinson model (modified to include the effects of flexural deformations), as well as fully atomistic molecular dynamics simulations and first-principles density-functional theory (DFT) calculations, are able to reproduce and explain the experimental observations.
2012
4.
dos Santos, Ricardo P; Machado, Leonardo D; Legoas, Sergio B; Galvao, Douglas S
Tribological Properties of Graphene and Boron-Nitride Layers: A Fully Atomistic Molecular Dynamics Study Proceedings
Cambridge University Press, vol. 1407, 2012.
Abstract | Links | BibTeX | Tags: Boron Nitride, Graphene, Molecular Dynamics, Tribology
@proceedings{dos2012tribological,
title = {Tribological Properties of Graphene and Boron-Nitride Layers: A Fully Atomistic Molecular Dynamics Study},
author = {dos Santos, Ricardo P and Machado, Leonardo D and Legoas, Sergio B and Galvao, Douglas S},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8537106&fileId=S1946427412007063},
year = {2012},
date = {2012-01-01},
journal = {MRS Proceedings},
volume = {1407},
pages = {mrsf11--1407},
publisher = {Cambridge University Press},
abstract = {Graphene has been one of the most important subjects in materials science in the last years. Recently, the frictional characteristics of atomically thin sheets were experimentally investigated using atomic force microscopy (AFM). A new mechanism to explain the enhanced friction for these materials, based on elastic compliance has been proposed. Here, we have investigated the tribological properties of graphene and boron-nitride (single and multi-layers) membranes using fully atomistic molecular dynamics simulations. These simulations were carried out using classical force fields, as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. The used structural models contain typically hundreds of thousands of atoms. In order to mimic the experimental conditions, an artificial AFM tip was moved over the membranes and the tribological characteristics determined in terms of forces and energies. Our results are in good agreement with the available experimental data. They show that the observed enhanced tribological properties can be explained in terms of out-of-plane geometrical distortions and elastic waves propagation. They validate the general features of the model proposed by Lee et al. (Science 328, 76 (2010).},
keywords = {Boron Nitride, Graphene, Molecular Dynamics, Tribology},
pubstate = {published},
tppubtype = {proceedings}
}
Graphene has been one of the most important subjects in materials science in the last years. Recently, the frictional characteristics of atomically thin sheets were experimentally investigated using atomic force microscopy (AFM). A new mechanism to explain the enhanced friction for these materials, based on elastic compliance has been proposed. Here, we have investigated the tribological properties of graphene and boron-nitride (single and multi-layers) membranes using fully atomistic molecular dynamics simulations. These simulations were carried out using classical force fields, as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. The used structural models contain typically hundreds of thousands of atoms. In order to mimic the experimental conditions, an artificial AFM tip was moved over the membranes and the tribological characteristics determined in terms of forces and energies. Our results are in good agreement with the available experimental data. They show that the observed enhanced tribological properties can be explained in terms of out-of-plane geometrical distortions and elastic waves propagation. They validate the general features of the model proposed by Lee et al. (Science 328, 76 (2010).
2008
3.
Nakabayashi, D; Ugarte, D; Moreau, ALD; Coluci, VR; Galvao, DS; Cotta, MA
Carbon nanotubes as R-bars of high aspect ratio composite nanotools Technical Report
2008.
Abstract | Links | BibTeX | Tags: AFM tips, Carbon Nanotubes, Nanocomposites, Tribology
@techreport{nakabayashi2008carbonb,
title = {Carbon nanotubes as R-bars of high aspect ratio composite nanotools},
author = {Nakabayashi, D and Ugarte, D and Moreau, ALD and Coluci, VR and Galvao, DS and Cotta, MA},
url = {http://lnls.cnpem.br/ar2008/},
year = {2008},
date = {2008-01-01},
abstract = {Nano technology requires the development of nano scale tools to manipulate nano systems. From the point of view of materials science, this represents a serious challenge, because nano tools must meet a series of stringent requirements of shape (size, aspect ratio), mechanical, magnetic and electrical properties. We have developed long and narrow carbon-carbon composite nano tips using carbon nanotubes covered by an amorphous carbon shell; the very small nano tube tip remained uncoated to preserve apex size. This configuration renders the system stiffer and allows for the control of flexibility and vibrations. In addition, we have maintained the important nano tube properties of size, strength and resilience. Nano manipulation experiments in situ in a high resolution scanning electron microscope were used to optimize the tips behavior and molecular dynamics simulations were used to study the mechanical response. Finally, we performed a practical application in atomic force microscopy. Composite tips yielded excellent image resolution and showed remarkable wear resistance (no degradation of image quality after acquiring several hundred images). },
keywords = {AFM tips, Carbon Nanotubes, Nanocomposites, Tribology},
pubstate = {published},
tppubtype = {techreport}
}
Nano technology requires the development of nano scale tools to manipulate nano systems. From the point of view of materials science, this represents a serious challenge, because nano tools must meet a series of stringent requirements of shape (size, aspect ratio), mechanical, magnetic and electrical properties. We have developed long and narrow carbon-carbon composite nano tips using carbon nanotubes covered by an amorphous carbon shell; the very small nano tube tip remained uncoated to preserve apex size. This configuration renders the system stiffer and allows for the control of flexibility and vibrations. In addition, we have maintained the important nano tube properties of size, strength and resilience. Nano manipulation experiments in situ in a high resolution scanning electron microscope were used to optimize the tips behavior and molecular dynamics simulations were used to study the mechanical response. Finally, we performed a practical application in atomic force microscopy. Composite tips yielded excellent image resolution and showed remarkable wear resistance (no degradation of image quality after acquiring several hundred images).
2.
Nakabayashi, D; Moreau, ALD; Coluci, VR; Galvao, DS; Cotta, MA; Ugarte, D
Carbon nanotubes as reinforcement elements of composite nanotools Journal Article
In: Nano letters, vol. 8, no. 3, pp. 842–847, 2008.
Abstract | Links | BibTeX | Tags: AFM tips, Carbon Nanotubes, Molecular Dynamics, Nanocomposites, Tribology
@article{nakabayashi2008carbon,
title = {Carbon nanotubes as reinforcement elements of composite nanotools},
author = {Nakabayashi, D and Moreau, ALD and Coluci, VR and Galvao, DS and Cotta, MA and Ugarte, D},
url = {http://pubs.acs.org/doi/abs/10.1021/nl0729633},
year = {2008},
date = {2008-01-01},
journal = {Nano letters},
volume = {8},
number = {3},
pages = {842--847},
publisher = {American Chemical Society},
abstract = {Nanotechnology is stimulating the development of nanomanipulators, including tips to interact with individual nanosystems. Fabricating nanotips fulfilling the requirements of shape (size, aspect ratio), mechanical, magnetic, and electrical properties is a material science challenge. Here, we report the generation of reinforced carbon−carbon composite nanotools using a nanotube (CNTs) covered by an amorphous carbon matrix (shell); the CNT tip protruded and remained uncoated to preserve apex size. Unsuitable properties such as flexibility and vibration could be controlled without deteriorating the CNT size, strength, and resilience. Nanomanipulation experiments and molecular dynamics simulations have been used to study the mechanical response of these composite beams under bending efforts. AFM probes based on these C−C composite high aspect ratio tips generated excellent image resolution and showed no degradation after acquiring several hundred (400) images.},
keywords = {AFM tips, Carbon Nanotubes, Molecular Dynamics, Nanocomposites, Tribology},
pubstate = {published},
tppubtype = {article}
}
Nanotechnology is stimulating the development of nanomanipulators, including tips to interact with individual nanosystems. Fabricating nanotips fulfilling the requirements of shape (size, aspect ratio), mechanical, magnetic, and electrical properties is a material science challenge. Here, we report the generation of reinforced carbon−carbon composite nanotools using a nanotube (CNTs) covered by an amorphous carbon matrix (shell); the CNT tip protruded and remained uncoated to preserve apex size. Unsuitable properties such as flexibility and vibration could be controlled without deteriorating the CNT size, strength, and resilience. Nanomanipulation experiments and molecular dynamics simulations have been used to study the mechanical response of these composite beams under bending efforts. AFM probes based on these C−C composite high aspect ratio tips generated excellent image resolution and showed no degradation after acquiring several hundred (400) images.
2004
1.
Legoas, Sergio B; Giro, Ronaldo; Galvao, Douglas S
Molecular dynamics simulations of C6) nanobearings Journal Article
In: Chemical physics letters, vol. 386, no. 4, pp. 425–429, 2004.
Abstract | Links | BibTeX | Tags: C60, Fullerenes, Molecular Dynamics, Nanobearing, Tribology
@article{legoas2004molecular,
title = {Molecular dynamics simulations of C6) nanobearings},
author = {Legoas, Sergio B and Giro, Ronaldo and Galvao, Douglas S},
url = {http://www.sciencedirect.com/science/article/pii/S000926140400168X},
year = {2004},
date = {2004-01-01},
journal = {Chemical physics letters},
volume = {386},
number = {4},
pages = {425--429},
publisher = {Elsevier},
abstract = {Recently was reported an ultra-lubricated system based on C60 molecules deposited over graphite layers. In that work a stick-slip rolling model for C60 molecules was proposed to explain the observed ultra-low friction force. In this Letter, we report the first molecular dynamics studies for these systems. Our results show that the AB stacking is not observed and the main experimental features can be explained without invoking stick-slip motions.
},
keywords = {C60, Fullerenes, Molecular Dynamics, Nanobearing, Tribology},
pubstate = {published},
tppubtype = {article}
}
Recently was reported an ultra-lubricated system based on C60 molecules deposited over graphite layers. In that work a stick-slip rolling model for C60 molecules was proposed to explain the observed ultra-low friction force. In this Letter, we report the first molecular dynamics studies for these systems. Our results show that the AB stacking is not observed and the main experimental features can be explained without invoking stick-slip motions.
http://scholar.google.com/citations?hl=en&user=95SvbM8AAAAJ
