scholarly journals Tuning friction to a superlubric state via in-plane straining

2019 ◽  
Vol 116 (49) ◽  
pp. 24452-24456 ◽  
Author(s):  
Shuai Zhang ◽  
Yuan Hou ◽  
Suzhi Li ◽  
Luqi Liu ◽  
Zhong Zhang ◽  
...  
Keyword(s):  
Atomic Scale ◽  
Atomistic Simulations ◽  
Contact Interface ◽  
Frictional Behavior ◽  
Flexible Materials ◽  
On Demand ◽  
Scale Structures ◽  
Unusual Strain ◽  
Strain Dependent ◽  
Additional Channel

Controlling, and in many cases minimizing, friction is a goal that has long been pursued in history. From the classic Amontons–Coulomb law to the recent nanoscale experiments, the steady-state friction is found to be an inherent property of a sliding interface, which typically cannot be altered on demand. In this work, we show that the friction on a graphene sheet can be tuned reversibly by simple mechanical straining. In particular, by applying a tensile strain (up to 0.60%), we are able to achieve a superlubric state (coefficient of friction nearly 0.001) on a suspended graphene. Our atomistic simulations together with atomically resolved friction images reveal that the in-plane strain effectively modulates the flexibility of graphene. Consequently, the local pinning capability of the contact interface is changed, resulting in the unusual strain-dependent frictional behavior. This work demonstrates that the deformability of atomic-scale structures can provide an additional channel of regulating the friction of contact interfaces involving configurationally flexible materials.

scholarly journals Dynamic lattice distortions driven by surface trapping in semiconductor nanocrystals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Burak Guzelturk ◽  
Benjamin L. Cotts ◽  
Dipti Jasrasaria ◽  
John P. Philbin ◽  
David A. Hanifi ◽  
...  
Keyword(s):  
Photon Energy ◽  
Semiconductor Nanocrystals ◽  
Atomic Scale ◽  
Atomistic Simulations ◽  
Shell System ◽  
Structural Distortions ◽  
Colloidal Semiconductor Nanocrystals ◽  
Femtosecond Electron Diffraction ◽  
Structural Deformations ◽  
Nonradiative Processes

AbstractNonradiative processes limit optoelectronic functionality of nanocrystals and curb their device performance. Nevertheless, the dynamic structural origins of nonradiative relaxations in such materials are not understood. Here, femtosecond electron diffraction measurements corroborated by atomistic simulations uncover transient lattice deformations accompanying radiationless electronic processes in colloidal semiconductor nanocrystals. Investigation of the excitation energy dependence in a core/shell system shows that hot carriers created by a photon energy considerably larger than the bandgap induce structural distortions at nanocrystal surfaces on few picosecond timescales associated with the localization of trapped holes. On the other hand, carriers created by a photon energy close to the bandgap of the core in the same system result in transient lattice heating that occurs on a much longer 200 picosecond timescale, dominated by an Auger heating mechanism. Elucidation of the structural deformations associated with the surface trapping of hot holes provides atomic-scale insights into the mechanisms deteriorating optoelectronic performance and a pathway towards minimizing these losses in nanocrystal devices.

Direct Nanoscale Patterning by Atomic Manipulation

1995 ◽  
Vol 380 ◽  
Author(s):  
Craig T. Salling
Keyword(s):  
Scanning Tunneling Microscope ◽  
Room Temperature ◽  
Atomic Layer ◽  
Sample Surface ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Nanoscale Patterning ◽  
Direct Patterning ◽  
Scale Structures ◽  
Atomic Manipulation

ABSTRACTThe ability to create atomic-scale structures with the scanning tunneling microscope (STM) plays an important role in the development of a future nanoscale technology. I briefly review the various modes of STM-based fabrication and atomic manipulation. I focus on using a UHV-STM to directly pattern the Si(001) surface by atomic manipulation at room temperature. By carefully adjusting the tip morphology and pulse voltage, a single atomic layer can be removed from the sample surface to define features one atom deep. Segments of individual dimer rows can be removed to create structures with atomically straight edges and with lateral features as small as one dimer wide. Trenches ∼3 nm wide and 2–3 atomic layers deep can be created with less stringent control of patterning parameters. Direct patterning provides a straightforward route to the fabrication of nanoscale test structures under UHV conditions of cleanliness.

Tuning Local Electrical Conductivity via Fine Atomic Scale Structures of Two-Dimensional Interfaces

Nano Letters ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 6030-6036 ◽  
Author(s):  
Shuai Zhang ◽  
Lei Gao ◽  
Aisheng Song ◽  
Xiaohu Zheng ◽  
Quanzhou Yao ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Atomic Scale ◽  
Two Dimensional ◽  
Scale Structures

New Insights into the Atomic-Scale Structures and Behavior of Steels

2012 ◽  
Vol 20 (4) ◽  
pp. 44-48 ◽  
Author(s):  
E. A. Marquis ◽  
P.-Pa Choi ◽  
F. Danoix ◽  
K. Kruska ◽  
S. Lozano-Perez ◽  
...  
Keyword(s):  
Cluster Formation ◽  
Atom Probe ◽  
Design Criterion ◽  
Atomic Scale ◽  
Grain Structure ◽  
Microstructural Stability ◽  
Scale Structures ◽  
Boundary Chemistry ◽  
And Behavior ◽  
Controlled Precipitation

Atom probe tomography (APT) has significantly contributed to our understanding and development of structural materials through the detailed analysis of solute behavior, cluster formation, precipitate evolution, and interfacial and grain boundary chemistry. Whether one is concerned with light alloys, Ni-based superalloys, or steels, the design objectives are similar: developing alloys with optimum properties (strength, toughness, ductility, fatigue resistance, creep strength) through controlled precipitation, grain structure, solute state, and combination of phases. Performance in service, through microstructural stability and resistance to degradation, is also a major design criterion for the development of novel materials.

scholarly journals Hrem Of General And Twist Grain Boundaries

1999 ◽  
Vol 5 (S2) ◽  
pp. 108-109
Author(s):  
K. L. Merkle ◽  
L. J. Thompson
Keyword(s):  
Thin Film ◽  
Electron Beam ◽  
Phase Space ◽  
Grain Boundaries ◽  
Scale Structure ◽  
Zone Axis ◽  
Low Energy ◽  
Atomic Scale ◽  
Dimensional Phase Space ◽  
Scale Structures

The observation of atomic-scale structures of grain boundaries (GBs) via axial illumination HREM has been largely restricted to tilt GBs, due to the requirement that the electron beam be parallel to a low-index zone axis on both sides of the interface. This condition can be fulfilled for all tilt GBs with misorientation about a low-index direction. The information obtained through HREM studies in many materials has brought important insights concerning the atomic-scale structure of such boundaries. However, it is well known that tilt GBs occupy only an infinitesimally small fraction of the 5-dimensional phase space which describes the macroscopic geometry of all GBs. Therefore, although tilt GBs are very important due to their low energy, it would be usefulto also study twist GBs and general GBs that contain twist and tilt components.We have prepared thin-film Au samples by an epitaxy technique in which (01l) and (001) grains are grown side by side.

Structure of Dislocation Cores in GaAs

2003 ◽  
Vol 779 ◽  
Author(s):  
S. P. Beckman ◽  
D. C. Chrzan
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Ab Initio ◽  
Partial Dislocation ◽  
Atomic Scale ◽  
The Core ◽  
Partial Dislocations ◽  
Double Period ◽  
Single Period ◽  
Scale Structures

AbstractThe atomic scale structures of the partial dislocation cores in GaAs are explored using ab initio electronic structure total energy techniques. The structure of the 30° partial dislocations are expected to be period doubled along the core. The structure of the 90° partial dislocations remains more uncertain, and here, an effort is made to predict which of two proposed reconstruction, double period or single period, is more stable. The relative energies of the two core structures are found to be equal, within the accuracy of the present calculations. It is suggested that at temperature, both core reconstructions will be present.

Atomic-Scale Modeling of the Annihilation of Jogged Screw Dislocation Dipoles

1999 ◽  
Vol 578 ◽  
Author(s):  
T. Vegge ◽  
O. B. Pedersen ◽  
T. Leffers ◽  
K. W. Jacobsen
Keyword(s):  
Molecular Dynamics ◽  
Screw Dislocation ◽  
Atomic Scale ◽  
Atomistic Simulations ◽  
Elastic Band ◽  
Screw Dislocations ◽  
Scale Modeling ◽  
Band Method

AbstractUsing atomistic simulations we investigate the annihilation of screw dislocation dipoles in Cu. In particular we determine the influence of jogs on the annihilation barrier for screw dislocation dipoles. The simulations involve energy minimizations, molecular dynamics, and the Nudged Elastic Band method. We find that jogs on screw dislocations substantially reduce the annihilation barrier, hence leading to an increase in the minimum stable dipole height.

Study of Nanocutting Using Atomic Model

2008 ◽  
Vol 33-37 ◽  
pp. 963-968
Author(s):  
Chun Yi Chu ◽  
Chung Ming Tan ◽  
Yung Chuan Chiou
Keyword(s):  
Molecular Dynamics ◽  
Energy Minimization ◽  
Atomic Scale ◽  
Scale Model ◽  
Atomistic Simulations ◽  
Cutting Depth ◽  
Cutting Deformation ◽  
Simulation Results ◽  
Model Approach

The stress induced in a workpiece under nanocutting are analyzed by an atomic-scale model approach that is based on the energy minimization. Certain aspects of the deformation evolution during the process of nanocutting are addressed. This method needs less computational efforts than traditional molecular dynamics (MD) calculations. The simulation results demonstrate that the microscopic cutting deformation mechanism in the nanocutting process can be regarded as the instability of the crystalline structure in our atomistic simulations and the surface quality of the finished workpiece varies with the cutting depth.

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