Reconciliation of the microcrystalline and the continuous random network model for amorphous semiconductors

2000 ◽  
Vol 638 ◽  
Author(s):  
J.K. Bording ◽  
J. Tafto
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Molecular Dynamics Simulations ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Volume Fraction ◽  
Random Network ◽  
Amorphous Material ◽  
Dynamics Simulations ◽  
Continuous Random Network

AbstractWe show by molecular dynamics simulations, that the radial distribution function of an amorphous material does not change significantly by introducing a considerable volume fraction of nanocrystals. The nanocrystals, embedded in a continuous random network, ensure a certain degree of medium range order in the amorphous material. Our simulations, which are on germanium, show that microcrystals smaller than 2 nm can comprise at least 20 % of the volume without significantly changing the radial distribution function from that of pure continuous random network. By increasing the size of the crystals, without altering the crystal to amorphous volume ratio, the radial distribution changes. The molecular dynamics simulations show that the nanocrystals are unchanged at low temperature. At higher temperature the mobility and critical size of the grains increase, transforming the sub-critical crystalline grains into the surrounding continuous random network matrix.

scholarly journals Universal self-assembly of one-component three-dimensional dodecagonal quasicrystals

Soft Matter ◽  
2017 ◽  
Vol 13 (29) ◽  
pp. 5076-5082 ◽  
Author(s):  
Roman Ryltsev ◽  
Nikolay Chtchelkatchev
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Molecular Dynamics Simulations ◽  
Radial Distribution Function ◽  
Self Assembly ◽  
Three Dimensional ◽  
Analytical Continuation ◽  
Length Scale ◽  
Component Systems ◽  
Dynamics Simulations

Using molecular dynamics simulations and new method based on numerical analytical continuation of the radial distribution function, we find universal criterion for dodecagonal quasicrystal formation in one-component systems with two-length-scale potentials.

Effect of Substrate Temperature and Incident Energy for Alloyzation of Co onto Cu(001) Substrate

2008 ◽  
Vol 47-50 ◽  
pp. 375-378 ◽  
Author(s):  
Zheng Han Hong ◽  
Shun Fa Hwang ◽  
Te Hua Fang
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Substrate Temperature ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Incident Energy

The mixing situation of Co atoms implanting onto Cu(001) substrate is investigated with regard to incident energy and substrate temperature by molecular dynamics. The results indicate that higher substrate temperature and/or incident energy will result in higher intermixing between the incident atoms and the substrate atoms. Furthermore, the value of the first peak of the radial distribution function (RDF) becomes lower and wider for the Co-Cu system as the substrate temperature and/or incident energy are increased.

Melting at Mg/Al interface in Mg-Al-Mg nanolayer by molecular dynamics simulations

2021 ◽  
Author(s):  
Xue-Qi Lv ◽  
Xiong-Ying Li
Keyword(s):  
Molecular Dynamics ◽  
Heat Capacity ◽  
Distribution Function ◽  
Potential Energy ◽  
Density Distribution ◽  
Molecular Dynamics Simulations ◽  
Regional Research ◽  
Melting Temperatures ◽  
Essential Step ◽  
Dynamics Simulations

Abstract The melting at the magnesium/aluminum (Mg/Al) interface is an essential step during the fabrications of Mg-Al structural materials and biomaterials. We carried out molecular dynamics simulations on the melting at the Mg/Al interface in a Mg-Al-Mg nanolayer via analyzing the changes of average atomic potential energy, Lindemann index, heat capacity, atomic density distribution and radial distribution function with temperature. The melting temperatures (T m) of the nanolayer and the slabs near the interface are significantly sensitive to the heating rate (v h) over the range of v h≤4.0 K/ps. The distance (d) range in which the interface affects the melting of the slabs is predicted to be (-98.2, 89.9) Å at v h→0, if the interface is put at d=0 and Mg (Al) is located at the left (right) side of the interface. The (T m) of the Mg (Al) slab just near the interface (e.g., d=4.0 Å) is predicted to be 926.8 K (926.6 K) at v h→0, with 36.9 K (37.1 K) below 963.7 K for the nanolayer. These results highlight the importance of regional research on the melting at an interface in the nanolayers consisting of two different metals.

Experimental Studies and Molecular Dynamics Simulations of the Sliding Contact of Metallic Glass

2000 ◽  
Vol 644 ◽  
Author(s):  
Xi-Yong Fu ◽  
Michael L. Falk ◽  
David A. Rigney
Keyword(s):  
Molecular Dynamics ◽  
Metallic Glass ◽  
Molecular Dynamics Simulations ◽  
Bulk Metallic Glass ◽  
Amorphous Material ◽  
Experimental Studies ◽  
Sliding Contact ◽  
Atomic Scale ◽  
Sliding Interface ◽  
Dynamics Simulations

AbstractTribological properties of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 were studied experimentally using a pin/disk geometry without lubrication. Experimental observations were compared with 2D molecular dynamics simulations of amorphous material in sliding contact. The friction coefficient and the wear rate of bulk metallic glass (BMG) depend on normal load and test environment. The sliding of annealed BMG re-amorphizes devitrified material. A mechanically mixed layer is generated during sliding; this layer has enhanced oxygen content if the sliding is in air. The MD simulations show that atomic scale mixing occurs across the sliding interface. The growth kinetics of the mixing process scales with the square root of time. In the simulations, a low density region is generated near the sliding interface; it corresponds spatially to the softer layer detected in experiments. Subsurface displacement profiles produced by sliding and by simulation are very similar and are consistent with the flow patterns expected from a simple Navier-Stokes analysis when the stress state involves both compression and shear.

Liquid Layering and the Enhanced Thermal Conductivity of Ar-Cu Nanofluids: A Molecular Dynamics Study

2016 ◽  
Author(s):  
Jithu Paul ◽  
A. K. Madhu ◽  
U. B. Jayadeep ◽  
C. B. Sobhan
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Particle Size ◽  
Molecular Dynamics Simulations ◽  
Volume Fraction ◽  
Strong Dependence ◽  
Particle Sizes ◽  
Dynamics Simulations ◽  
Enhanced Thermal Conductivity ◽  
Liquid Layering

Nanofluids — colloidal suspensions of nanoparticles in base fluids — are known to possess superior thermal properties compared to the base fluids. Various theoretical models have been suggested to explain the often anomalous enhancement of these properties. Liquid layering around the nanoparticle is one of such reasons. The effect of the particle size on the extent of liquid layering around the nanoparticle has been investigated in the present study. Classical molecular dynamics simulations have been performed in the investigation, considering the case of a copper nanoparticle suspended in liquid argon. The results show a strong dependence of thickness of the liquid layer on the particle size, below a particle diameter of 4nm. To establish the role of liquid layering in the enhancement of thermal conductivity, simulations have been performed at constant volume fraction for different particle sizes using Green Kubo formalism. The thermal conductivity results show 100% enhancement at 3.34% volume fraction for particle size of 2nm. The results establish the dominant role played by liquid layering in the enhanced thermal conductivity of nanofluids at the low particle sizes used. Contrary to the previous findings, the molecular dynamics simulations also predict a strong dependence of the liquid layer thickness on the particle size in the case of small particles.

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