scholarly journals Study of Effect of Size on Iron Nanoparticle by Molecular Dynamics Simulation

2021 ◽  
Vol 2 (3) ◽  
pp. 158-167
Author(s):  
Pham Huu Kien ◽  
Yiachu Khamphone ◽  
Giap Thi Thuy Trang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Iron Nanoparticles ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Iron Nanoparticle ◽  
Crystal Cluster ◽  
The Core ◽  
The One

We use the molecular dynamics simulation to study iron nanoparticles (NPs) consisting of 4000, 5000, 6000 atoms at temperatures of 300 and 900 K. The crystallization and microstructure were analyzed through the pair radial distribution function (PRDF), the potential energy per atom, the distribution of atom types and dynamical local structure parameters <fx>, where x is the bcc, ico or 14. The simulation indicated that amorphous NP contains a large number of ico-type atoms that play a role in preventing the crystallization. Amorphous NP is crystallized through transformations of f14 > 0 and fbcc = 0 type to bcc-type atoms when it is annealed at 900 K upon 40 ns. The growth of crystal clusters happens parallel with changing its microstructure. The behavior of the crystal cluster resembles the nucleation process described by classical nucleation theory. Furthermore, we found that the amorphous NP has two parts: the core has the structure similar to the one of amorphous bulk, in while the surface structure is more porous amorphous. Unlike amorphous NP, the crystalline NP also has three parts: the core is the bcc, the next part the distorted bcc and the surface is amorphous. Amorphous and crystalline NPs have part core which has the structure not depend on size. Doi: 10.28991/HIJ-2021-02-03-01 Full Text: PDF

Molecular Dynamics Simulation of Nano Cluster-Seed Effects on Heterogeneous Nucleation

2009 ◽  
Author(s):  
Donguk Suh ◽  
Seung-chai Jung ◽  
Woong-sup Yoon
Keyword(s):  
Molecular Dynamics ◽  
Heterogeneous Nucleation ◽  
Three Dimensional ◽  
Seed Mass ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Supersaturation Ratio ◽  
Order Of Magnitude ◽  
Nano Cluster

A three-dimensional heterogeneous nucleation is simulated by classical molecular dynamics, where the Lennard-Jones gas and solid nano cluster-seed molecules have argon and aluminum properties, respectively. All dimensions of the wall are periodic and a soft core carrier gas within the system controls the temperature rise induced by latent heat of condensation. There are three shapes of cluster-seeds being cube, rod, and sphere, three classes of masses, and the simulation took place under nine supersaturation ratios, making a total of 81 calculations. An analysis of variance was performed under a three-way layout to analyze the cluster-seed and supersaturation ratio effects on the system. For supersaturation ratios above the critical value nucleation rates were evaluated, below growth rates, and overall liquefaction rates were each defined and calculated. Results show that the supersaturation ratio dominantly controls all rates, but seed characteristics are important for the growth of the largest cluster under the critical supersaturation ratio. Overall liquefaction increases subject to an escalation of supersaturation ratio and seed mass. However, the significance of the supersaturation ratio for overall liquefaction suggests that thermal diffusion is more dominant than mass interactions for this system. Homogeneous characteristics are also compared with the heterogeneous system to find that though nucleation may occur for an insufficient supersaturation ratio when a seed is within the system, the addition of a seed does not in fact facilitate the increase in rates of the phenomena at high supersaturation ratios. Finally a comparison with the classical nucleation theory asserts a 3 to 4 order of magnitude difference, which is within the lines of deviation when it comes to theory and molecular simulations.

A study to investigate phase transitions and nucleation kinetics of nickel and copper

2016 ◽  
Vol 30 (11) ◽  
pp. 1650129 ◽  
Author(s):  
F. A. Celik ◽  
A. K. Yildiz
Keyword(s):  
Molecular Dynamics ◽  
Orientational Order ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Structural Development ◽  
Nucleation Kinetics ◽  
Embedded Atom ◽  
Bond Orientational Order ◽  
Kinetics Of

In this study, we investigate the homogeneous nucleation kinetics of copper and nickel system during cooling process using molecular dynamics simulation (MDS). The calculation is carried out for a different number of atoms consisting of 500, 2048, 8788 and 13,500 based on embedded atom method (EAM). It is observed that the melting points for the both model increases with increasing the size of systems (i.e. the number of atoms) as expected from Parrinello and Rahman MD method. The interfacial free energies and critical nucleus radius of nickel and copper are also determined by molecular dynamics, and the results are consistent with the classical nucleation theory. The structural development and phase transformation are also determined from the radial distribution function (RDF) and local bond orientational order parameters (LBOO).

Molecular Dynamics Based Analysis of Nucleation and Surface Energy of Droplets in Supersaturated Vapors of Methane and Ethane

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Jadran Vrabec ◽  
Martin Horsch ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Droplet Size ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
First Passage Time ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Classical Nucleation Theory ◽  
Critical Droplet

Homogeneous nucleation processes are characterized by the nucleation rate and the critical droplet size. Molecular dynamics simulation is applied for studying homogeneous nucleation during condensation of supersaturated vapors of methane and ethane. The results are compared with the classical nucleation theory (CNT) and the Laaksonen–Ford–Kulmala (LFK) model that introduces the size dependence of the specific surface energy. It is shown for the nucleation rate that the Yasuoka–Matsumoto method and the mean first passage time method lead to considerably differing results. Even more significant deviations are found between two other approaches to the critical droplet size, based on the maximum of the Gibbs free energy of droplet formation (Yasuoka–Matsumoto) and the supersaturation dependence of the nucleation rate (nucleation theorem). CNT is found to agree reasonably well with the simulation results, whereas LFK leads to large deviations at high temperatures.

Molecular Dynamics Simulation of Bubble Nucleation in Superheated Liquid

2010 ◽  
Author(s):  
Chao Liu ◽  
Xiaobo Wu ◽  
Hualing Zhang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Argon Atom ◽  
Bubble Nucleation ◽  
Nucleation Theory ◽  
Dynamics Simulation ◽  
Superheated Liquid ◽  
Classic Nucleation Theory

The bubble homogeneous nucleation in superheated liquid argon is studied by molecular dynamics simulation in NVT ensemble. L-J potential is adopted for the interaction of argon atom. The simulated particle numbers of argon atom is 10976. The non-dimensional size of simulated box is 27.8×27.8×27.8. The initial non-dimensional temperature and density are 0.4 and 0.51 separately. The results show that the bubble homogeneous nucleation is divided into the waiting process, the appearing process of numerous small bubble nucleuses and the aggregation process of small bubble nucleuses. By fitting simulated data, we find that the bubble nucleation rate is eight orders of magnitudes bigger than the result of classic nucleation theory. The bubble nucleation rate increases along with the increasing of density and superheated temperature, which agrees well with one of classic nucleation theory.

Mechanical properties of Ge/Si core-shell nanowires under a uniaxial tension

2006 ◽  
Vol 958 ◽  
Author(s):  
Y. Yano ◽  
T. Nakajima ◽  
K. Shintani
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Single Atom ◽  
Core Shell ◽  
The Core ◽  
Young’S Moduli ◽  
Vegard’S Law ◽  
Shell Nanowires

ABSTRACTThe mechanical properties of Si/Ge core-shell nanowires under a unixial tension are studied using molecular-dynamics simulation. The effects of anisotropy and the fraction of the core atoms on the Young's moduli of the core-shell nanowires are examined. The values of their Young's moduli deviate from those calculated using Vegard's law. Single atom chains are formed at the final stages of elongation of the nanowires.

scholarly journals The Structure and Crystallization Process of Amorphous Iron Nanoparticles

2019 ◽  
Vol 35 (3) ◽  
Author(s):  
Duong Thi Thanh ◽  
Pham Mai An ◽  
Giap Thi Thuy Trang ◽  
Nguyen Thi Minh Thuy ◽  
Pham Huu Kien
Keyword(s):  
Physical Chemistry ◽  
Crystal Structure ◽  
Molecular Dynamics ◽  
Tio2 Nanoparticles ◽  
Iron Nanoparticles ◽  
Crystallization Process ◽  
Condensed Matter ◽  
Amorphous Iron ◽  
Iron Nanoparticle ◽  
Crystal Cluster

This paper studies the crystallization process and structure of amorphous iron nanoparticles by molecular dynamics method. The study shows that amorphous iron nanoparticles could not be crystallized at 300 K and 500 K. Iron nanoparticle, annealed at 900 K over a long time, was crystallized into a BCC crystal structure. The structure of crystallized iron nanoparticle at 900 K was analyzed through the pair radial distribution function and the number of crystal atoms upon various regions in nanoparticles. The simulation revealed that the first nuclei was formed most frequently in the area near the surface of the nanoparticle. Then the crystal cluster grew toward the centre of the nanoparticle. The completely crystallized nanoparticle had two components: the core with a BCC crystal structure and surface with an amorphous structure. As for the amorphous nanoparticle at 300 or 500 K, crystal-clusters were too small to grow large enough to crystallize the nanoparticle.   Keywords Iron nanoparticle, crystallize, annealing, crystal atom, crystal cluster. References [1] J.D. Honeycutt, C.H. Andersen, Molecular dynamics study of melting and freezing of small Lennard-Jones clusters, Journal of Physical Chemistry 91 (1987) 4950-4963. https://doi.org/ 10.1021/j100303a014.[2] H. Shin, H.S. Jung, K.S. Hong and J.K. Lee, Crystallization process of TiO2 nanoparticles in an acidic solution, Chemistry letters 33 (2004) 1382-1383. https://doi.org/10.1246/cl.2004. 1382.[3] D. Shi, Z. Li, Y. Zhang, X. Kou, L. Wang, J. Wang, J. Li, Synthesis and characterizations of amorphous titania nanoparticles, Nanoscience and Nanotechnology Letters 1 (2009) 165-170. https://doi.org/10.1166/nnl.2009.1037.[4] D.N. Srivastava, N. Perkas, A. Gedanken, I. Felner, Sonochemical synthesis of mesoporous iron oxide and accounts of its magnetic and catalytic properties, The Journal of Physical Chemistry B 106 (2002) 1878-1883. https://doi. org/10.1021/jp015532w.[5] N. Zaim, A. Zaim and M. Kerouad, The hysteresis behavior of an amorphous core/shell magnetic nanoparticle, Physica B: Condensed Matter 549 (2018) 102-106. https://doi.org/ 10.1016/j.physb. 2017.10.071.[6] L. Gao and Q. Zhang, Effects of amorphous contents and particle size on the photocatalytic properties of TiO2 nanoparticles, Scripta materialia 44 (2001) 1195-1198. https://doi.org/ 10. 1016/S1359-6462(01)00681-9.[7] G. Madras, B.J. McCoy, Kinetic model for transformation from nanosized amorphous TiO2 to anatase, Crystal growth & design 7 (2007) 250-253. https://doi.org/10.1021/cg060272z.[8] C.I. Wu, J.W. Huang, Y.L. Wen, S.B. Wen, Y.H. Shen, M.Y. Yeh, Preparation of TiO2 nanoparticles by supercritical carbon dioxide, Materials Letters 62 (2008) 1923-1926. https://doi.org/10. 1016/j.matlet.2007.10.043.[9] C. Pan, P. Shen and S.Y. Chen, Condensation and crystallization and coalescence of amorphous Al2O3 nanoparticles, Journal of crystal growth 299 (2007) 393-398. https://doi.org/ 10. 1016/j.jcrysgro.2006.12.006.[10] M. Epifani, E. Pellicer, J. Arbiol, N. Sergent, T. Pagnier, J.R. Morante, Capping ligand effects on the amorphous-to-crystalline transition of CdSe nanoparticles, Langmuir 24 (2008) 11182-11188. https://doi.org/10.1021/la801859z.[11] P.H. Kien, M.T. Lan, N.T. Dung, P.K. Hung, Annealing study of amorphous bulk and nanoparticle iron using molecular dynamics simulation. International Journal of Modern Physics B 28 (2014) 1450155 (17 page). https:// doi.org/10.1142/S0217979214501550.[12] V.V. Hoang and N.H. Cuong, Local icosahedral order and thermodynamics of simulated amorphous Fe. Physica B: Condensed Matter 404 (2009) 340-346. https://doi.org/10.1016/ j.physb. 2008.10.057.        

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