Atomic-Scale Simulation of Defect Cluster Formation in High-Energy Displacement Cascades in Zirconium

2008 ◽  
pp. 299-299-15
Author(s):  
RE Voskoboinikov ◽  
YN Osetsky ◽  
DJ Bacon
Keyword(s):  
Cluster Formation ◽  
High Energy ◽  
Defect Cluster ◽  
Atomic Scale ◽  
Displacement Cascades

Defect Cluster Formation in High Energy Displacement Cascades in Copper

2000 ◽  
Vol 650 ◽  
Author(s):  
Yuri N. Osetsky ◽  
David J. Bacon
Keyword(s):  
Cluster Formation ◽  
Pair Potential ◽  
Simulation Method ◽  
High Energy ◽  
Interatomic Potentials ◽  
Dislocation Loops ◽  
Many Body ◽  
Displacement Cascades ◽  
Stacking Fault Tetrahedra ◽  
Body Potential

ABSTRACTPrimary radiation damage in displacement cascades in metals has been studied extensively by atomistic simulation during the last decade. The variety of defect types observed in cascade simulation is not entirely consistent with experimental data. For example, experiments on copper show a very effective production of stacking fault tetrahedra (SFTs) but this was not observed systematically in cascade simulation. To clarify this and related issues, extensive simulation of displacement cascades in copper have been performed using two different interatomic potentials, a short-range many-body potential and a long-range pair potential. We have studied the damage created by primary knock-on-atoms of energy up to 20keV, i.e. below the energy range for formation of subcascades, at temperatures 100 and 600K. Special attention was paid to cascade statistics and the accuracy of simulation in the collision stage. The former required many simulations for each temperature whereas the latter involved a modification of the simulation method. The results on variety of clusters observed, e.g. SFTs, glissile and sessile interstitial clusters, and faulted and perfect interstitial dislocation loops, lead to conclusions on the effect of the potentials and the significant variation of the number of Frenkel pairs and clustering effects produced in different cascades under the same conditions.

From Adatom Migration to Chemical Kinetics: Models for MBE, Mombe and MOCVD

1993 ◽  
Vol 312 ◽  
Author(s):  
D. D. Vvedensky ◽  
T. Shitarat ◽  
P. Smilauer ◽  
T. Kaneko ◽  
A. Zangwill
Keyword(s):  
Experimental Data ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
High Energy ◽  
Atomic Scale ◽  
Basic Model ◽  
Mobile Species ◽  
Local Environments ◽  
Starting Point

AbstractThe application of Monte Carlo simulations to various epitaxial growth methods is examined from the standpoint of incorporating only those kinetics processes that are required to explain experimental data. A basic model for molecular-beam epitaxy (MBE) is first introduced and some of the features that make it suitable for describing atomic-scale processes are pointed out. Extensions of this model for cases where the atomic constituents of the growing surface are delivered in the form of heteroatomic molecules are then considered. The experimental scenarios that is discussed is the homoepitaxy of GaAs(001) using metalorganic molecular-beam epitaxy (MOMBE) with triethylgallium (TEG) and precursors and using MOCVD with trimethylgallium (TMG). For MOMBE, the comparisons between simulations and experiments are based on reflection high-energy electron diffraction intensities, by analogy with comparisons made for MBE, while for metalorganic chemical vapor deposition (MOCVD) the simulations are compared to in situ glancingincidence x-ray scattering measurements. In both of these cases, the inclusion of a second mobile species to represent the precursor together with various rules for the decomposition of this molecule (in terms of rates and local environments) with be shown to provide a useful starting point for explaining the general trends in the experimental data and for further refinements of the model.

Displacement cascade evolution in tungsten with pre-existing helium and hydrogen clusters: a molecular dynamics study

2020 ◽  
Vol 111 (8) ◽  
pp. 698-705
Author(s):  
Mohammad Abu-Shams ◽  
Jeffery Moran ◽  
Ishraq Shabib
Keyword(s):  
Molecular Dynamics ◽  
Point Defect ◽  
Radiation Damage ◽  
Point Defects ◽  
High Energy ◽  
Dynamics Simulation ◽  
Power Relationship ◽  
Hydrogen Clusters ◽  
Displacement Cascades ◽  
Hydrogen Defects

Abstract The effects of radiation damage on bcc tungsten with preexisting helium and hydrogen clusters have been investigated in a high-energy environment via a comprehensive molecular dynamics simulation study. This research determines the interactions of displacement cascades with helium and hydrogen clusters integrated into a tungsten crystal generating point defect statistics. Helium or hydrogen clusters of atoms~0.1% of the total number of atoms have been randomly distributed within the simulation model and primary knock-on-atom (PKA) energies of 2.5, 5, 7.5 and 10 keV have been used to generate displacement cascades. The simulations quantify the extent of radiation damage during a simulated irradiation cycle using the Wigner-Seitz point defect identification technique. The generated point defects in crystals with and without pre-existing helium/hydrogen defects exhibit a power relationship with applied PKA energy. The point defects are classified by their atom type, defect type, and distribution within the irradiated model. The presence of pre-existing helium and hydrogen clusters significantly increases the defects (5 - 15 times versus pure tungsten models). The vacancy composition is primarily tungsten (e. g., ~70% at 2.5 keV) in models with pre-existing helium, but the interstitials are primarily He (e. g., ~89% at 10 keV). On the other hand, models with pre-existing hydrogen have a vacancy composition that is primarily tungsten (more than 90% irrespective of PKA energy), and the interstitial composition is more balanced between tungsten (average 46%) and hydrogen (average 54%) interstitials across the PKA range. The distribution of the atoms reveals that the tungsten point defects prefer to reside close to the position of cascade initiation, but helium or hydrogen defects reside close to the positions where clusters are built.

scholarly journals Creation and Evaluation of Atomically Ordered Side- and Facet-Surface Structures of Three-Dimensional Silicon Nano-Architectures

2020 ◽  
Author(s):  
Azusa N. Hattori ◽  
Ken Hattori
Keyword(s):  
Electron Diffraction ◽  
Surface Science ◽  
Three Dimensional ◽  
Annealing Treatment ◽  
High Energy ◽  
Energy Electron ◽  
Atomic Scale ◽  
Methods Of Evaluation ◽  
Facet Surface ◽  
Microscopy Techniques

The realization of three-dimensional (3D)-architected nanostructures, that is, the transformation from novel two-dimensional (2D) film-based devices to 3D complex nanodevices, is of crucial importance with the progress of scaling down devices to nanometer order. However, little attention has been devoted to controlling the atomic ordering and structures of side-surfaces on 3D structures, while techniques for controlling and investigating 2D surfaces, namely, surface science, have been established only for planar 2D surfaces. We have established an original methodology that enables atomic orderings and arrangements of surfaces with arbitrary directions to be observed on 3D figured structures by developing diffraction and microscopy techniques. An original technique, namely, directly and quantitatively viewing the side- and facet-surfaces at the atomic scale by reflection high-energy electron diffraction (RHEED) and low-energy electron diffraction (LEED), can be used to determine process parameters in etching. This chapter introduces methods of evaluation by RHEED and LEED based on a reciprocal space map and methods of creating various atomically flat 111 and {100} side-surfaces of 3D Si nano-architectures and tilted 111 facet-surfaces fabricated by lithography dry and wet etching processes, followed by annealing treatment in vacuum.

Theoretical prediction and atomic-scale investigation of a tetra-VN2 monolayer as a high energy alkali ion storage material for rechargeable batteries

2019 ◽  
Vol 7 (47) ◽  
pp. 26858-26866 ◽  
Author(s):  
Jing Xu ◽  
Dashuai Wang ◽  
Yanhui Liu ◽  
Ruqian Lian ◽  
Xinying Gao ◽  
...  
Keyword(s):  
Energy Density ◽  
Rate Capability ◽  
High Energy ◽  
Rechargeable Batteries ◽  
Atomic Scale ◽  
High Energy Density ◽  
Storage Material ◽  
Transition Metal Nitride ◽  
Ion Storage ◽  
Alkali Ion

A new 2D transition metal nitride tetra-VN2 monolayer with a superior rate capability and a high energy density could be used as a potential alkali ion storage material for high energy rechargeable batteries.

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.

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