Atomistic two-temperature modelling of ion track formation in silicon dioxide

Leino, Aleksi A.; Daraszewicz, Szymon L.; Pakarinen, Olli H.; Nordlund, K.; Djurabekova, Flyura

doi:10.1209/0295-5075/110/16004

Cited by 29 publications

(22 citation statements)

References 51 publications

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“…This approach is a further development of the classical inelastic thermal spike two temperature model [52,53]. The dynamic energy exchange between electronic and ionic subsystems in graphene is followed by using a concurrent multiscale model implemented within a molecular dynamics code [42]. The model assumes that the high velocity electrons generated along the ion path spread out in the target, depositing energy by electronic collisions and exciting electrons.…”

Section: Two Temperature Molecular Dynamics Modelmentioning

confidence: 99%

“…The MD simulations were performed with the PARCAS MD code [57] modified to include the electronic energy exchange [42]. The choice of the interatomic potential in this case is particularly important since the lattice heat capacity and thermal conductivity are intrinsic properties of the potential.…”

Section: Two Temperature Molecular Dynamics Modelmentioning

confidence: 99%

“…In this study, we report a combined experimental and theoretical study of defect formation in suspended graphene by SHI ions. The induced defects are analyzed by Raman spectroscopy in combination with the two temperature molecular dynamics (TTMD) model [42], which couples the ionic and electronic subsystems in a concurrent multiscale simulation. This model was able to resolve inconsistency of experimental observations by SAXS and RBS measurements reported in [43] in contrast to the instantaneous thermal spike model [44].…”

Section: Introductionmentioning

confidence: 99%

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Creating nanoporous graphene with swift heavy ions

Vázquez

Åhlgren

Ochedowski

et al. 2017

Carbon

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We examine swift heavy ion-induced defect production in suspended single layer graphene using Raman spectroscopy and a two temperature molecular dynamics model that couples the ionic and electronic subsystems. We show that an increase in the electronic stopping power of the ion results in an increase in the size of the pore-type defects, with a defect formation threshold at 1.22-1.48 keV/layer. We also report calculations of the specific electronic heat capacity of graphene with different chemical potentials and discuss the electronic thermal conductivity of graphene at high electronic temperatures, suggesting a value in the range of 1 Wm −1 K −1. These results indicate that swift heavy ions can create nanopores in graphene, and that their size can be tuned between 1-4 nm diameter by choosing a suitable stopping power.

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Section: Two Temperature Molecular Dynamics Modelmentioning

confidence: 99%

Section: Two Temperature Molecular Dynamics Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Creating nanoporous graphene with swift heavy ions

Vázquez

Åhlgren

Ochedowski

et al. 2017

Carbon

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“…The model was coupled to MD to give an extended version of 2T-MD and used to model SHI irradiation in Ge [68]. As argued above, however, the use of the electron density as an additional parameter is unnecessary, and other studies of SHI irradiation in Si [37], UO2 [69] and SiO2 [70] have omitted it.…”

Section: Shi Irradiationmentioning

confidence: 99%

Modelling radiation effects in solids with two-temperature molecular dynamics

Darkins

Duffy

2018

Computational Materials Science

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The ability to predict the structural modifications of materials resulting from a broad range of irradiation scenarios would have a positive impact on many fields of science and technology. Established techniques for modelling large atomic systems, such as classical molecular dynamics, are limited by the neglect of the electronic degrees of freedom which restricts their application to irradiation events that primarily interact with atomic nuclei. Ab initio methods, on the other hand, include electronic degrees of freedom, but the requisite computational costs restrict their application to relatively small systems. Recent methodological developments aimed at overcoming some of these limitations are based on methods that couple atomistic models to a continuum model for the electronic energy, where energy is exchanged between the nuclei and electrons via electronic stopping and electron-phonon coupling mechanisms. Such two-temperature molecular dynamics models, as they are known, make it practicable to simulate the effects of electronic excitations on systems with millions, or even hundreds of millions, of atoms. They have been used to study laser irradiation of metallic films, swift heavy ion irradiation of metals and semiconductors, and moderately high ion irradiation of metals. In this review we describe the two-temperature molecular dynamics methodology and the various practical considerations required for its implementation. We provide example applications of the model to multiple irradiation scenarios that accommodate electronic excitations. We also describe the challenges of including the effects of the modification of the interatomic interactions, due to the excitation of electrons, in the simulations and how these challenges can be overcome.

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“…Recently the conventional iTS-TT approach has been improved by the two-temperature molecular dynamics (TT-MD) [9], where the atomic system is evolved by MD equation (2b) while the electronic system is evolved by the heat-diffusion equation (2a), i.e.,…”

Section: Introductionmentioning

confidence: 99%

Vaporlike phase of amorphous SiO2 is not a prerequisite for the core/shell ion tracks or ion shaping

Amekura

Kluth

Mota‐Santiago

et al. 2018

Phys. Rev. Materials

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When a swift heavy ion (SHI) penetrates amorphous SiO 2 , a core/shell (C/S) ion track is formed, which consists of a lower-density core and a higher-density shell. According to the conventional inelastic thermal spike (iTS) model represented by a pair of coupled heat equations, the C/S tracks are believed to form via "vaporization" and melting of the SiO 2 induced by SHI (V-M model). However, the model does not describe what the vaporization in confined ion-track geometry with a condensed matter density is. Here we reexamine this hypothesis. While the total and core radii of the C/S tracks determined by small angle x-ray scattering are in good agreement with the vaporization and melting radii calculated from the conventional iTS model under high electronic stopping power (S e) irradiations (>10 keV/nm), the deviations between them are evident at lowS e irradiation (3-5 keV/nm). Even though the iTS calculations exclude the vaporization of SiO 2 at the low S e , both the formation of the C/S tracks and the ion shaping of nanoparticles (NPs) are experimentally confirmed, indicating the inconsistency with the V-M model. Molecular dynamics (MD) simulations based on the two-temperature model, which is an atomic-level modeling extension of the conventional iTS, clarified that the "vaporlike" phase exists at S e ∼ 5 keV/nm or higher as a nonequilibrium phase where atoms have higher kinetic energies than the vaporization energy, but are confined at a nearly condensed matter density. Simultaneously, the simulations indicate that the vaporization is not induced under 50-MeV Si irradiation (S e ∼ 3 keV/nm), but the C/S tracks and the ion shaping of nanoparticles are nevertheless induced. Even though the final density variations in the C/S tracks are very small at the low stopping power values (both in the simulations and experiments), the MD simulations show that the ion shaping can be explained by flow of liquid metal from the NP into the transient low-density phase of the track core during the first ∼10 ps after the ion impact. The ion shaping correlates with the recovery process of the silica matrix after emitting a pressure wave. Thus, the vaporization is not a prerequisite for the C/S tracks and the ion shaping.

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Atomistic two-temperature modelling of ion track formation in silicon dioxide

Cited by 29 publications

References 51 publications

Creating nanoporous graphene with swift heavy ions

Creating nanoporous graphene with swift heavy ions

Modelling radiation effects in solids with two-temperature molecular dynamics

Vaporlike phase of amorphous SiO2 is not a prerequisite for the core/shell ion tracks or ion shaping

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