A molecular dynamics study of collisional heat transfer to nanoclusters in the gas phase

Hui, Yang; Song, Guanyu; Hogan, Christopher J.

doi:10.1016/j.jaerosci.2021.105891

Cited by 14 publications

(4 citation statements)

References 63 publications

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“…That thermal isolation is possible at a low EAC, which is an efficiency of conductive heat transfer on the interface, i.e., the ratio of the energy transferred upon a single molecule collision to that at the full accommodation. Note that in literature two terms are used for the same, namely, the energy accommodation coefficient and the thermal accommodation coefficient 19 . In our opinion, since it deals with energy, the term “energy accommodation coefficient” is more accurate to describe the process.…”

Section: Resultsmentioning

confidence: 99%

Fundamental insight into critical phenomena in condensation growth of nanoparticles in a flame

Altman

Fomenko

Agranovski

2022

Sci Rep

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The paper deals with the gas-phase formation of nanoparticles that is a fundamental process responsible for the condensed matter in the Universe, which also attracts attention due to its involvement in the particle synthesis for various nanotechnology applications. Previously reported results on MgO nano-oxides formed by Mg combustion showed a unique phenomenon coined “the condensation stagnation” that is the occurrence of critical clusters with suppressed growth. Here we focus on the effect of an external ionizer on this condensation growth stagnation. We show that the condensation stagnation occurring in the Mg particle flame subjected to a positive ion flux is similar to that in the unaffected flame. In contrast, applying negative charging significantly influences the state of stagnation of the system, i.e., no critical clusters are observed in the products sampled from the flame. The discovered critical behavior of the state of stagnation is explained in terms of the heat transfer between the condensed MgO nanoparticles and the surrounding gas, which efficiency depends on the sign of the nanoparticle charge. This dependence of the heat transfer efficiency on the nanoparticle charge is a new fundamental effect that should become the basis for accurate modeling in two-phase high-temperature systems.

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Section: Resultsmentioning

confidence: 99%

Fundamental insight into critical phenomena in condensation growth of nanoparticles in a flame

Altman

Fomenko

Agranovski

2022

Sci Rep

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“…Thus, compared to the pure Si case, a structured SiGe cluster, along with diverse cluster compositions, may yield unique dynamic behaviors during film growth. Due to insufficient heat dissipation [34], the temperature of the clusters, defined by the mean kinetic energy and derived from the average atom velocities, shows higher average temperatures than the system's heat bath. As for the Si and Ge atoms, they exhibit irregular behavior due to the collisions of surface atoms with the surrounding argon atoms, depending on the different cluster sizes and compositions [35].…”

Section: Formation and Characteristics Of Mixed Sige Nanoclustersmentioning

confidence: 99%

Cluster-Assisted Mesoplasma Chemical Vapor Deposition for Fast Epitaxial Growth of SiGe/Si Heterostructures: A Molecular Dynamics Simulation Study

Wang,

Li,

Ohta

et al. 2024

Materials

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Co-condensation of mixed SiGe nanoclusters and impingement of SiGe nanoclusters on a Si substrate were applied using molecular dynamics (MD) simulation in this study to mimic the fast epitaxial growth of SiGe/Si heterostructures under mesoplasma chemical vapor deposition (CVD) conditions. The condensation dynamics and properties of the SiGe nanoclusters during the simulations were investigated first, and then the impingement of transient SiGe nanoclusters on both Si smooth and trench substrate surfaces under varying conditions was studied theoretically. The results show that the mixed nanoclusters as precursors demonstrate potential for enhancing epitaxial SiGe film growth at a high growth rate, owing to their loosely bound atomic structures and high mobility on the substrate surface. By varying cluster sizes and substrate temperatures, this study also reveals that smaller clusters and higher substrate temperatures contribute to faster structural ordering and smoother surface morphologies. Furthermore, the formed layers display a consistent SiGe composition, closely aligning with nominal values, and the cluster-assisted deposition method achieves the epitaxial bridging of heterostructures during cluster impingement, highlighting its additional distinctive characteristics. The implications of this work make it clear that the mechanism of fast alloyed epitaxial film growth by cluster-assisted mesoplasma CVD is critical for extending it as a versatile platform for synthesizing various epitaxial films.

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“…The authors reported that both simulation techniques yield the same results for the investigated nanochannel setup. Recently, Yang et al 23 investigated the collisional heat transfer between gold and copper nanoparticles and either gaseous He, Ar, H 2 , or N 2 . The authors simulated differently sized nanoparticles and determined thermal accommodation coefficients consistent with previous theoretical and experimental work.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Molecular dynamics simulations are widely used for gaining insights into heat transfer processes, especially at nanoscales. − Zhakhovsky et al used molecular dynamics simulations to validate and enhance their numerical solutions of the Boltzmann equation for heat and mass transfer through evaporation and condensation at surfaces. The authors used molecular dynamics, in particular, to model the dynamics at the fluid–solid boundary.…”

Section: Introductionmentioning

confidence: 99%

Non-Boltzmann Heat Transfer between a Monatomic Gas and a Solid Nanostructure

Döntgen,

Heufer

2024

J. Phys. Chem. C

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The effect of non-Boltzmann energy distributions on the pressure, impingement rate, and heat flux of a monatomic gas in contact with a solid surface is investigated via theory and simulation. First, microcanonical formulations of the pressure, impingement rate, and heat flux are derived from first principles and integrated with prototypical energy distributions. Second, atomistic molecular dynamics simulations of an iron nanowire in a low-pressure argon atmosphere are used to test the non-Boltzmann heat flux theory. While pressure is found to be unaffected by the energy distribution of the gas, the impingement rate increases by up to 8.5% in the non-Boltzmann case. Most intriguingly, non-Boltzmann energy distributions can lead to a negative heat flux, meaning that heat flows from the cold solid to the hot gas. This non-Boltzmann heat flux effect is validated via the molecular dynamics simulations, and the solid is found to be 46% colder than the gas in the case of a hypothetical equilibrium for the upper-limiting non-Boltzmann energy distributions. The present fundamental findings provide novel insights into the properties of non-Boltzmann gases and improve the understanding of nonequilibrium dynamics.

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A molecular dynamics study of collisional heat transfer to nanoclusters in the gas phase

Cited by 14 publications

References 63 publications

Fundamental insight into critical phenomena in condensation growth of nanoparticles in a flame

Fundamental insight into critical phenomena in condensation growth of nanoparticles in a flame

Cluster-Assisted Mesoplasma Chemical Vapor Deposition for Fast Epitaxial Growth of SiGe/Si Heterostructures: A Molecular Dynamics Simulation Study

Non-Boltzmann Heat Transfer between a Monatomic Gas and a Solid Nanostructure

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