Atomistic simulation of point defects in silicon at high temperature

1996 ◽  
Vol 68 (21) ◽  
pp. 3028-3030 ◽  
Author(s):  
Talid Sinno ◽  
Z. Kurt Jiang ◽  
Robert A. Brown
Keyword(s):  
High Temperature ◽  
Point Defects ◽  
Atomistic Simulation

Atomistic Simulation Studies of the Effects of Defects on Thermal Properties of Ultra High Temperature Ceramics

2016 ◽  
Author(s):  
S. N. Medyanik ◽  
N. Vlahopoulos
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Thermal Properties ◽  
High Temperature ◽  
Point Defects ◽  
Atomistic Simulation ◽  
Atomistic Simulations ◽  
Hypersonic Vehicles ◽  
Simulation Studies ◽  
Ultra High Temperature Ceramics

Due to the harsh environments created by high speeds, significant new demands are placed on materials used for constructing hypersonic vehicles. Ultra high temperature ceramics (UHTCs) like carbides and borides exhibit unique thermal properties, such as very high melting points and good thermal conductivities. These properties make the ceramic materials good candidates for applications like Thermal Protection Systems (TPS) of the hypersonic vehicles. However, thermal properties of UHTCs may be very sensitive to microstructures of the materials. Thus, atomic scale defects may impact certain thermal properties, such as thermal conductivity. The effects of such small defects may be properly studied only through atomistic simulation methods, such as molecular dynamics (MD). Previously, atomistic simulation studies have been performed for the effects of point defects on thermal properties in silicon carbide (SiC). In addition, atomistic simulations have been applied to assess thermal conductivity in zirconium diboride (ZrB2) for perfect crystals and polycrystals. However, to our knowledge, no studies of the effects of point defects have been performed for zirconium diboride. This paper applies atomistic simulations to assess the impact of point defects on thermal conductivity in ZrB2 perfect crystals. Recently derived interatomic potential for ZrB2 along with LAMMPS molecular simulation package and MedeA software environment are employed in this effort. Phonon part of the thermal conductivity is calculated using Green-Kubo method. Calculations for a perfect crystal are conducted first and the results are compared to experimental data available from the literature. Then, several types of point defects are considered (vacancies, substitutions, and interstitials) and their impact on the phonon conductivity is evaluated. It is found that even a small concentration of point defects may have substantial effect and result in a reduction in the thermal conductivity values by almost an order of magnitude. The obtained results are in good qualitative agreement with previous studies conducted for silicon carbide. The methodology which is utilized in this work, the modeling procedure, and the obtained results are discussed in this paper.

Multiscale Modeling of Uranium Mononitride: Point Defects Diffusion, Self-Diffusion, Phase Composition

2017 ◽  
Vol 375 ◽  
pp. 101-113 ◽  
Author(s):  
Sergey Starikov ◽  
Alexey Kuksin ◽  
Daria Smirnova ◽  
Alexey Dolgodvorov ◽  
Vladimir Ozrin
Keyword(s):  
Nuclear Fuel ◽  
Point Defects ◽  
Atomistic Simulation ◽  
Nitrogen Pressure ◽  
Computational Approach ◽  
Self Diffusion ◽  
Partial Nitrogen Pressure ◽  
Diffusion Phase ◽  
Fuel Behavior ◽  
Uranium Mononitride

Multiscale computational approach is used to evaluate microscopic parameters for description of nitride nuclear fuel. The results of atomistic simulation and thermodynamic modeling allow to estimate diffusivity and concentrations of point defects at various stoichiometric ratios of UN1+x. The diffusivities of Xe atom were calculated in various equilibrium states. In addition, we obtained the dependence of partial nitrogen pressure on x and temperature. The results of atomistic simulation were used for modeling of nuclear fuel behavior with use of mechanistic fuel codes.

Instabilities and Point Defects at Step-Free Si(001) and (111) Terraces During High Temperature Annealing

1999 ◽  
Vol 587 ◽  
Author(s):  
Doohan Lee ◽  
Jack M. Blakely
Keyword(s):  
High Temperature ◽  
Point Defect ◽  
Point Defects ◽  
Strain Energy ◽  
Annealing Temperature ◽  
Small Islands ◽  
High Temperature Annealing ◽  
Atomic Steps ◽  
The Stability

AbstractIn this paper we describe observations on the stability of extremely large Si(001) and (111) terraces that are formed by a technique described previously. Following annealing at high temperature and quenching, a series of concentric pits of monoatomic depth are observed with spacing between successive pits of the order of several microns; pits do not form on (111) until the terraces get extremely large. The occurrence of small islands or small pits on the terraces of quenched samples gives information on the majority point defect at the annealing temperature. On (001) samples that are slowly cooled from the annealing temperature, it is observed that pairs of atomic steps have formed on the large terrace; we believe that these result from the tendency of the surface to minimize the strain energy associated with the (2 × 1) reconstruction.

Atomistic simulation of the point defects in B2-type MoTa alloy

2009 ◽  
Vol 404 (16) ◽  
pp. 2178-2183 ◽  
Author(s):  
Jian-Min Zhang ◽  
Fang Wang ◽  
Ke-Wei Xu ◽  
Vincent Ji
Keyword(s):  
Point Defects ◽  
Atomistic Simulation

Grain-boundary source/sink behavior for point defects: An atomistic simulation study

2009 ◽  
Vol 100 (4) ◽  
pp. 550-555 ◽  
Author(s):  
Paul C. Millett ◽  
Dilpuneet S. Aidhy ◽  
Tapan Desai ◽  
Simon R. Phillpot ◽  
Dieter Wolf
Keyword(s):  
Grain Boundary ◽  
Point Defects ◽  
Simulation Study ◽  
Atomistic Simulation ◽  
Boundary Source ◽  
Source Sink

Atomistic simulation of point defects in L10-type CuAu ordered alloy

2010 ◽  
Vol 248 (4) ◽  
pp. 897-903 ◽  
Author(s):  
Zhong-Liang Lin ◽  
Yan Zhang ◽  
Jian-Min Zhang ◽  
Ke-Wei Xu
Keyword(s):  
Point Defects ◽  
Atomistic Simulation

Atomistic simulation of point defects in L12-type Au3Cu ordered alloy

2007 ◽  
Vol 436 (1-2) ◽  
pp. 23-29 ◽  
Author(s):  
Xiang-Lei Song ◽  
Jian-Min Zhang ◽  
Ke-Wei Xu
Keyword(s):  
Point Defects ◽  
Atomistic Simulation
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