scholarly journals Nanopore Formation in CeO2 Single Crystal by Ion Irradiation: A Molecular Dynamics Study

2021 ◽  
Vol 5 (4) ◽  
pp. 32
Author(s):  
Yasushi Sasajima ◽  
Ryuichi Kaminaga ◽  
Norito Ishikawa ◽  
Akihiro Iwase
Keyword(s):  
Molecular Dynamics ◽  
Single Crystal ◽  
Thermal Energy ◽  
Ion Irradiation ◽  
Unit Length ◽  
Maximum Size ◽  
Fluorite Structure ◽  
Thermal Spike ◽  
Precise Control ◽  
Dynamics Method

The nanopore formation process that occurs by supplying a thermal spike to single crystal CeO2 has been simulated using a molecular dynamics method. As the initial condition, high thermal energy was supplied to the atoms in a nano-cylinder placed at the center of a fluorite structure. A nanopore was generated abruptly at around 0.3 ps after the irradiation, grew to its maximum size at 0.5 ps, shrank during the time to 1.0 ps, and finally equilibrated. The nanopore size increased with increasing effective stopping power gSe (i.e., the thermal energy deposited per unit length in the specimen), but it became saturated when gSe was 0.8 keV/nm or more. This finding will provide useful information for precise control of the size of nanopores. Our simulation confirmed nanopore formation found in the actual experiment, irradiation of CeO2 with swift heavy ions, but could not reproduce crystalline hillock formation just above the nanopores.

Deformation Mechanism of Diamond Nanocutting Single-Crystal Copper Using Molecular Dynamics Simulatio

2011 ◽  
Vol 239-242 ◽  
pp. 2775-2778
Author(s):  
Jia Xuan Chen ◽  
Ying Chun Liang ◽  
Xia Yu ◽  
Zhi Guo Wang ◽  
Zhen Tong
Keyword(s):  
Molecular Dynamics ◽  
Single Crystal ◽  
Cutting Force ◽  
Dislocation Loop ◽  
Deformation Mechanism ◽  
Molecular Dynamics Method ◽  
Parameter Method ◽  
Removal Mechanism ◽  
Single Crystal Copper ◽  
Dynamics Method

To study the removal mechanism of materials during nano cutting, molecular dynamics method is adopted to simulate single crystal copper nanomachining processes, and subsurface defects evolvements and chip forming regulation are analyzed by revised centro-symmetry parameter method and the ratios of the tangential cutting forceand the normal cutting force. The results show that there are different defects under different cutting depths. When cutting depths is shallower, there are dislocation loop nucleation in the subsurface of the workpiece beneath the tool; however, when the cutting depths is deeper, there are dislocations nucleation and slipping along {101} plane and (111) plane. In addition, both tangential cutting forceand the normal cutting force decrease as the cutting depths decreasing. When the ratios of the normal cutting force and the tangential cutting force is below 0.9, the chip will be formed.

Computer Simulation of Bending Plastic Deformation and Creation of Dislocations in Copper Thin Films

1994 ◽  
Vol 367 ◽  
Author(s):  
H. Tsukahara ◽  
Y. Niwa ◽  
T. Takayama ◽  
Masao Doyama
Keyword(s):  
Thin Films ◽  
Molecular Dynamics ◽  
Computer Simulation ◽  
Plastic Deformation ◽  
Single Crystal ◽  
Slip Plane ◽  
Molecular Dynamics Method ◽  
Copper Single Crystal ◽  
Small Single Crystal ◽  
Dynamics Method

AbstractA small single crystal of copper with a notch has been bent by use of the molecular dynamics method. The bend axis was [110]. Dislocations were created near the tip of the notch and moved on (111) slip plane. Pulling a copper single crystal, half dislocations were created in such a way that the bending was compensated.

Mechanical properties of single crystal copper ellipsoidal nanoshells by molecular dynamics

2018 ◽  
Vol 32 (16) ◽  
pp. 1850196 ◽  
Author(s):  
Qinyou Yang ◽  
Zailin Yang ◽  
Yong Yang ◽  
Guowei Zhang ◽  
Yu Zhang
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Single Crystal ◽  
Normal Stress ◽  
Variable Thickness ◽  
Normal Stresses ◽  
Uniform Thickness ◽  
Single Crystal Copper ◽  
Dynamics Method ◽  
Elastic Stage

Single crystal copper ellipsoidal nanoshells under outer normal tensile loadings are investigated by the molecular dynamics method. Normal stress and Mises stress are introduced to describe the mechanical properties. The uniform thickness nanoshells, the variable thickness nanoshells and the variable radius nanoshells are simulated to elucidate the effect of thickness on yielding behaviors and other mechanical properties. Potential energies, stresses and dislocations of nanoshells are discussed in the paper. The dislocations of these nanoshells form an octagon or that with an external quadrangle. The variable thickness nanoshells break this shape slightly. The potential energies of nanoshells have stable stages and then increase. The outer normal stresses and Mises stresses of different models differ from eath other. The thickness of nanoshells affects the elastic stage and the variable thickness nanoshell has different mechanical properties with others. When the radiuses of nanoshells with the same thickness are different, their dislocation shapes are the pressed octagon. Thier normal yield stresses are different, but their Mises yield stress are same. Also, the outer shape determines the trend of curves. The structure of a sphere is steadier than that of an ellipsoid.

Study on phase transformation in cutting Ni-base superalloy based on molecular dynamics method

2020 ◽  
pp. 095440622095124 ◽  
Author(s):  
ZhaoPeng Hao ◽  
ZaiZhen Lou ◽  
YiHang Fan
Keyword(s):  
Molecular Dynamics ◽  
Phase Transformation ◽  
Single Crystal ◽  
Lattice Structure ◽  
Cutting Speed ◽  
Potential Functions ◽  
Molecular Dynamics Method ◽  
Dynamics Simulation ◽  
Nickel Based Alloy ◽  
Dynamics Method

Nickel-based single crystal alloys are widely used in aerospace and other important fields of national defense due to their excellent properties. Phase transformation occurs during high-speed cutting of nickel-based single crystal alloy, which seriously affects the surface quality. It is of great significance to carry out theoretical research on phase transformation for improving the machining quality of nickel-based alloy. In this paper, molecular dynamics method is used to study the nano-cutting of single crystal nickel-based alloy with silicon nitride ceramic tool. The mechanism of phase transformation and the effect of cutting speed on phase transformation in workpieces are studied in detail. The nano-cutting model is established. Morse potential functions for molecular dynamics simulation are calculated, and EAM and Tersoff potential functions are selected. The effect of cutting speed on phase transformation was studied by using radial distribution function, coordination number analysis, common neighbor analysis, and the deep reasons for the sharp change of lattice structure were analyzed from many aspects. Finally, in order to verify the universality of the research results and explore the new properties of compression, nano compression (the same strain rate as the nano cutting process) was simulated. The results show that the increase of cutting speed leads to the increase of hydrostatic stress, the increase of energy in crystal and the rise of cutting temperature. As a result, the change of lattice structure becomes more and more intense, and the conversion rate of different crystal structures increases greatly.

Molecular Dynamics Study on Shear Property of Single-Crystal Bi2Te3

2014 ◽  
Vol 787 ◽  
pp. 198-204 ◽  
Author(s):  
Ben Huang ◽  
Peng Cheng Zhai ◽  
Li Sheng Liu
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Single Crystal ◽  
Layer Structure ◽  
Strain Rate Effect ◽  
Shear Property ◽  
Shearing Deformation ◽  
Structural Fracture ◽  
Loading Modes ◽  
Dynamics Method

The shear property of the thermoelectric material Bi2Te3is inextricably linked with its layer structure. By the molecular dynamics method, the mechanism of shearing deformation was studied in this paper. In the simulation, cubic single-crystal simulation cells with different layer directions inside were adopted, ensuring that thecaxis of crystal lattice can be along, across and 45odeviated from the shear stress. Compared with all the calculation models, the results show that when the shear stress increases, slip occurs along the Te1-Te1 adjacent layers which are connected by the weak van der Waals bonding, and ultimately leads to structural fracture. Furthermore, size effect and loading modes can also impact the behavior of shearing deformation, however, in very different ways. Future efforts should be focused on the influence of the creation and motion of defects during the deformation as well as temperature effect and strain rate effect.

Computational Analysis of Heavy Ion-DNA Interaction Using Molecular Dynamics Method

2015 ◽  
Vol 643 ◽  
pp. 193-197
Author(s):  
Akie Nagao ◽  
You Yin ◽  
Sumio Hosaka
Keyword(s):  
Molecular Dynamics ◽  
Chemical Bond ◽  
Ion Irradiation ◽  
Dna Interaction ◽  
Heavy Ion ◽  
Dna Damages ◽  
Heavy Ion Irradiation ◽  
The One ◽  
Semi Empirical ◽  
Dynamics Method

We studied DNA damages in heavy ion irradiation for its radiotherapy using molecular dynamics (MD) method. We adopted semi-empirical hybrid quantum mechanics/molecular mechanics (QM/MM) method of Amber in order to investigate the cleavage of chemical bond by heavy ion in our simulation. We found the cleavage of chemical bond, although the simulated energy of heavy ion turned out to be slightly higher than the one determined by experiment.

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