Two-phase simulation of the crystalline silicon melting line at pressures from –1 to 3 GPa

Dozhdikov, V. S.; Basharin, A. Yu.; Levashov, P. R.

doi:10.1063/1.4739085

Cited by 32 publications

(13 citation statements)

References 51 publications

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“…The important thermophysical properties of the modeled silicon such as melting temperature [81], solidification and melting rates [82], thermal conductivity [83,84], bulk modulus [85], and phase diagram [60,86] reproduce the behavior of a real solid at the equilibrium conditions quite well. Moreover, the chosen potential gives better overall description of liquid phase than all frequently used potentials [87].…”

Section: Approachmentioning

confidence: 91%

Atomistic-continuum modeling of short laser pulse melting of Si targets

et al. 2014

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We present an atomistic-continuum model to simulate ultrashort laser-induced melting processes in semiconductor solids on the example of silicon. The kinetics of transient non-equilibrium phase transition mechanisms is addressed with a Molecular Dynamics method at atomic level, whereas the laser light absorption, strong generated electron-phonon non-equilibrium, fast diffusion and heat conduction due to photo-excited free carriers are accounted for in the continuum. We give a detailed description of the model, which is then applied to study the mechanism of short laser pulse melting of free standing Si films. The effect of laser-induced pressure and temperature of the lattice on the melting kinetics is investigated. Two competing melting mechanisms, heterogeneous and homogeneous, were identified. Apart of classical heterogeneous melting mechanism, the nucleation of the liquid phase homogeneously inside the material significantly contributes to the melting process. The simulations showed, that due to the open diamond structure of the crystal, the laser-generated internal compressive stresses reduce the crystal stability against the homogeneous melting. Consequently, the latter can take a massive character within several picoseconds upon the laser heating. Due to negative volume of melting of modeled Si material, -7.5%, the material contracts upon the phase transition, relaxes the compressive stresses and the subsequent melting proceeds heterogeneously until the excess of thermal energy is consumed. The threshold fluence value, at which homogeneous nucleation of liquid starts contributing to the classical heterogeneous propagation of the solid-liquid interface, is found from the series of simulations at different laser input fluences. On the example of Si, the laser melting kinetics of semiconductors was found to be noticeably different from that of metals with fcc crystal structure.Comment: 38 pages, 27 figure

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Section: Approachmentioning

confidence: 91%

Atomistic-continuum modeling of short laser pulse melting of Si targets

et al. 2014

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“…a) Evaluated through the two-phase method [45]. b) Evaluated from the derivative of the enthalpy with respect to temperature at constant pressure.…”

Section: Molecular Dynamics (Md) Simulationsmentioning

confidence: 99%

Disordering and dynamic self-organization in stoichiometric UO2 at high temperatures

Annamareddy

Eapen

2017

Journal of Nuclear Materials

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Using atomistic simulations and metrics from statistical mechanics we show that the oxygen anions in UO2 predominantly hop from one native (tetrahedral) lattice site to another, above a characteristic temperature Tα (~2000 K). Interestingly, we discover two types of disorder-the first one, which is a measure of the fraction of anions that are displaced from their native sites, portrays a monotonic increase with temperature and shows excellent conformity to neutron scattering data. The second metric demonstrates a dynamic clustering or self-organization behavior wherein the anions are spatially correlated to those with similar mobility. The dynamic self-organization, however, experiences a non-monotonic variation with temperature depicting a maximum near the Bredig or λ-transition. We further establish that the thermodynamic metric cp/T, which is equal to the rate of change of entropy with temperature, is a key thermodynamic indicator of the dynamic disorder among the oxygen anions.

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“…Despite its importance, the phase diagram of this class of potentials has not been thoroughly determined. For silicon, thermodynamic calculations have focused on the low-pressure melting line of the diamond crystal [16][17][18][19]. There is a surprising lack of thermodynamic data at intermediate and high pressure, where silicon is expected to undergo a dc to β-tin transition [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Novel stable crystalline phase for the Stillinger-Weber potential

2014

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Tetrahedral liquids such as silicon, germanium, carbon, water, and silica are an important class of materials not only for industrial applications but also for our understanding of nature. The Stillinger-Weber potential is one of the most popular models for computer simulations of these systems with tetrahedral coordination, with the directionality of the interactions introduced via a three-body repulsive term which promotes locally tetrahedral arrangements. This approach has been extended to various tetrahedral liquids, providing valuable insight into the physics of group XIV elements and more recently water. Perhaps surprisingly, a consistent thermodynamic picture of this class of models is still lacking despite their widespread usage. Here we fill this gap by computing equilibrium phase diagrams for the silicon and water parametrizations and report a novel crystal structure which dominates the models' phase diagram at intermediate and high pressure, and thus warrants further theoretical and numerical investigation. Our results redefine the phase behavior of an important class of tetrahedrally coordinated systems, and also suggest that a more stringent test for simulation models is the ability to select the experimentally relevant crystalline phases, as opposed to just reproducing their mechanical stability.

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Two-phase simulation of the crystalline silicon melting line at pressures from –1 to 3 GPa

Cited by 32 publications

References 51 publications

Atomistic-continuum modeling of short laser pulse melting of Si targets

Atomistic-continuum modeling of short laser pulse melting of Si targets

Disordering and dynamic self-organization in stoichiometric UO2 at high temperatures

Novel stable crystalline phase for the Stillinger-Weber potential

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