scholarly journals Atomic-Scale Friction Studies on Single-Crystal Gallium Arsenide Using Atomic Force Microscope and Molecular Dynamics Simulation

2021 ◽  
Author(s):  
Pengfei Fan ◽  
Saurav Goel ◽  
Xichun Luo ◽  
Hari M. Upadhyaya
Keyword(s):  
Molecular Dynamics ◽  
Gallium Arsenide ◽  
Atomic Force Microscope ◽  
Coefficient Of Friction ◽  
Kinetic Coefficient ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Atomic Force ◽  
Pile Up ◽  
Nanoscale Friction

AbstractThis paper provides a fresh perspective and new insights into nanoscale friction by investigating it through molecular dynamics (MD) simulation and atomic force microscope (AFM) nanoscratch experiments. This work considered gallium arsenide, an important III–V direct bandgap semiconductor material residing in the zincblende structure, as a reference sample material due to its growing usage in 5G communication devices. In the simulations, the scratch depth was tested as a variable in the fine range of 0.5–3 nm to understand the behavior of material removal and to gain insights into the nanoscale friction. Scratch force, normal force, and average cutting forces were extracted from the simulation to obtain two scalar quantities, namely, the scratch cutting energy (defined as the work performed to remove a unit volume of material) and the kinetic coefficient of friction (defined as the force ratio). A strong size effect was observed for scratch depths below 2 nm from the MD simulations and about 15 nm from the AFM experiments. A strong quantitative corroboration was obtained between the specific scratch energy determined by the MD simulations and the AFM experiments, and more qualitative corroboration was derived for the pile-up and the kinetic coefficient of friction. This conclusion suggests that the specific scratch energy is insensitive to the tool geometry and the scratch speed used in this investigation. However, the pile-up and kinetic coefficient of friction are dependent on the geometry of the tool tip.

An investigation of nanoindentation tests on the single crystal copper thin film via an atomic force microscope and molecular dynamics simulation

2007 ◽  
Vol 221 (2) ◽  
pp. 259-266 ◽  
Author(s):  
D Huo ◽  
Y Liang ◽  
K Cheng
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Size Effect ◽  
Single Crystal ◽  
Atomic Force Microscope ◽  
Md Simulations ◽  
Single Crystal Copper ◽  
Atomic Force

Nanoindentation tests performed in an atomic force microscope have been utilized to directly measure the mechanical properties of single crystal metal thin films fabricated by the vacuum vapour deposition technique. Nanoindentation tests were conducted at various indentation depths to study the effect of indentation depths on the mechanical properties of thin films. The results were interpreted by using the Oliver-Pharr method with which direct observation and measurement of the contact area are not required. The elastic modulus of the single crystal copper film at various indentation depths was determined as 67.0 > 6.9 GPa on average, which is in reasonable agreement with the results reported by others. The indentation hardness constantly increases with decreasing indentation depth, indicating a strong size effect. In addition to the experimental work, a three-dimensional nanoindentation model of molecular dynamics (MD) simulations with embedded atom method (EAM) potential is proposed to elucidate the mechanics and mechanisms of nanoindentation of thin films from the atomistic point of view. MD simulations results show that due to the size effect no distinct dislocations were observed in the plastic deformation processes of the single crystal copper thin films, which is significantly different from the plastic deformation mechanism in bulk materials.

Accelerated Molecular Dynamics Simulation of AFM Experiments Using the Bond-Boost Method

2008 ◽  
Vol 1085 ◽  
Author(s):  
Woo Kyun Kim ◽  
Michael L. Falk
Keyword(s):  
Molecular Dynamics ◽  
Md Simulations ◽  
Silicon Surfaces ◽  
Dynamics Simulation ◽  
Sliding Velocity ◽  
Atomic Processes ◽  
Accelerated Molecular Dynamics ◽  
Tomlinson Model ◽  
Atomic Force ◽  
Experimental Values

ABSTRACTAccelerated molecular dynamics (MD) simulations of recent Atomic Force Microscope (AFM) experiments on oxidized silicon surfaces demonstrate a nontrivial dependence of frictional force on sliding velocity as well as temperature. By implementing hyper dynamics (HD) via the bond-boost method these simulations achieve sliding velocities in the range of real experimental values. Moreover, an analysis of the effects of temperature and sliding velocity on friction provide evidence for a systematic deviation from the modified Tomlinson model. We hypothesize regarding the origin of these deviations, and use the simulations to analyze the atomic processes that accompany sliding.

Characteristics of the Water Meniscus at AFM Tip for Various Surface Energy

2008 ◽  
Author(s):  
Hojin Choi ◽  
Jung Yun Kim ◽  
Seungdo Hong ◽  
Joonkyung Jang ◽  
Man Yeong Ha
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Surface Energy ◽  
Equilibrium State ◽  
Atomic Force Microscope ◽  
Capillary Force ◽  
Flat Surface ◽  
Dynamics Simulation ◽  
Atomic Force ◽  
Water Meniscus

The atomic force microscope (AFM), invented by Binning et al [1], has become a useful tool for its application in various fields of research. Even though AFM shows outstanding performance, one problem is the large adhesion forces due to the formation of a water meniscus in ambient condition. Therefore, it is important to understand the properties of the water meniscus. In previous studies, a theoretical method or Monte Carlo method was used to model the water meniscus problem with the assumption of thermodynamic equilibrium. But the physical phenomenon, occurs in a real AFM environment, is difficult to reach the thermodynamic equilibrium state due to a continuous variation of the water meniscus structure. Through two methods, addressed upon, only shows the equilibrium state, they have many difficulties to make clear the mechanism of a water meniscus formation. Because it is also troublesome to simulate the formation process of a water meniscus, most of researches have only investigated the properties of the water meniscus. Molecular Dynamics Simulation (MD) is the most suitable method for our needs. We can not only obtain the capillary force of the water meniscus, but also visualize the forming mechanism of the water meniscus. For these reasons, the water meniscus is expected to be understood easier. We performed a molecular dynamics simulation of the water meniscus that forms between an atomic force microscope (AFM) tip and a flat solid surface. We obtained the density profile and the capillary force of the nano-scale meniscus. We also examined the structure change in the meniscus by scanning the AFM tip at various distances between the AFM tip and the flat surface. In the case of a hydrophilic tip and a hydrophobic flat surface, the water meniscus changes from convex to concave as the surface energy of the flat surface increases. Using Young-Laplace equation, we obtain the capillary force of the water meniscus. In the case of a hydrophilic tip and a hydrophilic flat surface, the capillary force decreases as the distance between the AFM tip and the flat surface increases. We also examined the radius of the water meniscus. As the distance increases, the radius gets smaller. At a distance over d = 2.5nm, the radius of the water meniscus starts to fluctuate due to the instability of the water meniscus becoming narrow.

scholarly journals Understanding Covalent Grafting of Nanotubes onto Polymer Nanocomposites: Molecular Dynamics Simulation Study

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2621
Author(s):  
Seunghwa Yang
Keyword(s):  
Molecular Dynamics ◽  
Load Transfer ◽  
Cell Model ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Covalent Grafting ◽  
Modelling Strategies ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
External Loads

Here, we systematically interrogate the effects of grafting single-walled (SWNT) and multi-walled carbon nanotubes (MWNT) to polymer matrices by using molecular dynamics (MD) simulations. We specifically investigate key material properties that include interfacial load transfer, alteration of nanotube properties, and dispersion of nanotubes in the polymer matrix. Simulations are conducted on a periodic unit cell model of the nanocomposite with a straight carbon nanotube and an amorphous polyethylene terephthalate (PET) matrix. For each type of nanotube, either 0%, 1.55%, or 3.1% of the carbon atoms in the outermost nanotubes are covalently grafted onto the carbon atoms of the PET matrix. Stress-strain curves and the elastic moduli of nanotubes and nanocomposites are determined based on the density of covalent grafting. Covalent grafting promotes two rivalling effects with respect to altering nanotube properties, and improvements in interfacial load transfer in the nanocomposites are clearly observed. The enhanced interface enables external loads applied to the nanocomposites to be efficiently transferred to the grafted nanotubes. Covalent functionalization of the nanotube surface with PET molecules can alter the solubility of nanotubes and improve dispersibility. Finally, we discuss the current limitations and challenges in using molecular modelling strategies to accurately predict properties on the nanotube and polymers systems studied here.

A Study on the Uniaxial Tension of FCC Metals at Nano Level Using MD

2008 ◽  
Vol 32 ◽  
pp. 255-258
Author(s):  
Bohayra Mortazavi ◽  
Akbar Afaghi Khatibi
Keyword(s):  
Molecular Dynamics ◽  
Uniaxial Tension ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Engineering Strain ◽  
Fcc Metals ◽  
Engineering Stress ◽  
Nano Science ◽  
Face Centered

Molecular Dynamics (MD) are now having orthodox means for simulation of matter in nano-scale. It can be regarded as an accurate alternative for experimental work in nano-science. In this paper, Molecular Dynamics simulation of uniaxial tension of some face centered cubic (FCC) metals (namely Au, Ag, Cu and Ni) at nano-level have been carried out. Sutton-Chen potential functions and velocity Verlet formulation of Noise-Hoover dynamic as well as periodic boundary conditions were applied. MD simulations at different loading rates and temperatures were conducted, and it was concluded that by increasing the temperature, maximum engineering stress decreases while engineering strain at failure is increasing. On the other hand, by increasing the loading rate both maximum engineering stress and strain at failure are increasing.

Molecular Dynamics Simulation of a Pullout Test on a Carbon Nanotube in a Polymer Matrix

2014 ◽  
Vol 1700 ◽  
pp. 61-66
Author(s):  
Guttormur Arnar Ingvason ◽  
Virginie Rollin
Keyword(s):  
Molecular Dynamics ◽  
Polymer Matrix ◽  
Large Scale ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Atomistic Simulations ◽  
Polymer Molecules ◽  
Molecular Potential ◽  
Pull Out ◽  
Walled Carbon Nanotubes

ABSTRACTAdding single walled carbon nanotubes (SWCNT) to a polymer matrix can improve the delamination properties of the composite. Due to the complexity of polymer molecules and the curing process, few 3-D Molecular Dynamics (MD) simulations of a polymer-SWCNT composite have been run. Our model runs on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), with a COMPASS (Condensed phase Optimized Molecular Potential for Atomistic Simulations Studies) potential. This potential includes non-bonded interactions, as well as bonds, angles and dihedrals to create a MD model for a SWCNT and EPON 862/DETDA (Diethyltoluenediamine) polymer matrix. Two simulations were performed in order to test the implementation of the COMPASS parameters. The first one was a tensile test on a SWCNT, leading to a Young’s modulus of 1.4 TPa at 300K. The second one was a pull-out test of a SWCNT from an originally uncured EPON 862/DETDA matrix.

Sign in / Sign up

Export Citation Format

Share Document