On the lower energy limit of electronic stopping in simulated collision cascades in Ni, Pd and Pt

Sand, Andrea E.; Nordlund, K.

doi:10.1016/j.jnucmat.2014.09.029

Cited by 32 publications

(17 citation statements)

References 31 publications

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Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

“…Electronic stopping of high-energy atoms reduces the peak size of the damaged region [15], as well as the extent of the residual damage after partial recrystallization [16]. The electronic stopping of lower energy atoms in insulators is less well understood but could be equally significant: in metals, electronic stopping of low-energy atoms can dominate energy transfer, as there are so many of them during the cooling phase of a cascade [17][18][19].Details of the electronic structure (such as the band gap and the density of states) play a fundamental role at low projectile velocities, so we use a first-principles molecular dynamics technique in which the electronic excitations are described by time-dependent density functional theory (TDDFT) with no adjustable parameters. This approach captures the complicated band-structure features of the silicon-plus-silicon system without treating the projectile as a weak perturbation.…”

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confidence: 99%

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Electron Elevator: Excitations across the Band Gap via a Dynamical Gap State

et al. 2016

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We use time-dependent density functional theory to study self-irradiated Si. We calculate the electronic stopping power of Si in Si by evaluating the energy transferred to the electrons per unit path length by an ion of kinetic energy from 1 eV to 100 keV moving through the host. Electronic stopping is found to be significant below the threshold velocity normally identified with transitions across the band gap. A structured crossover at low velocity exists in place of a hard threshold. An analysis of the time dependence of the transition rates using coupled linear rate equations enables one of the excitation mechanisms to be clearly identified: a defect state induced in the gap by the moving ion acts like an elevator and carries electrons across the band gap.

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Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

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confidence: 99%

Electron Elevator: Excitations across the Band Gap via a Dynamical Gap State

et al. 2016

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“…a neutron, and the damage energy is the amount of energy which is left in the ionic system after the energy lost to the electrons has been dynamically removed during the course of the simulation. This is implemented as a frictional term on all atoms with kinetic energy above 10 eV, which has been shown to be a reasonable choice for a cut-off [33]. The use of an energy threshold for electronic stopping is necessary, else all thermal modes are …”

Section: Simulationsmentioning

confidence: 99%

Non-equilibrium properties of interatomic potentials in cascade simulations in tungsten

Sand

Dequeker

Becquart

et al. 2016

Journal of Nuclear Materials

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“…A non-local friction force was applied to all atoms with kinetic energy above 10 eV to account for energy losses due to electronic stopping. This choice of threshold has proven to be suitable in a range of metals based on empirical evidence from ion beam mixing experiments [26], and capture the total heat losss from disordered cascade regions [27]. The stopping power was determined by the method used in SRIM [17].…”

Section: MDmentioning

confidence: 99%

Direct observation of the spatial distribution of primary cascade damage in tungsten

Mason

Sand

et al. 2018

Acta Materialia

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Recently we have presented direct experimental evidence for large defect clusters being formed in primary damage cascades in self-ion irradiated tungsten [Yi et al, EPL 110:36001 (2015)]. This large size is significant, as it implies strong elastic interaction between the defects will affect their subsequent evolution, especially if defects are formed close together. Here we present a direct experimental observation of the separation between visible defects in self-ion irradiated tungsten, in the form of a 2d pairwise radial distribution function extracted from transmission electron micrographs (TEM). We also present a detailed analysis of the observed radial distribution function, and infer the probable size and shape of individual cascades. We propose and validate a simple exponential form for the spatial distribution of defects within a single cascade. The cascade statistics necessary have been acquired by developing an automated procedure for analyzing black-dot damage in TEM micrographs. We confirm that the same model also produces a high-quality fit to the separation between larger defects observed in MD simulations. For the first time we present experimental evidence for the sub-nanometre-scale spatial distribution of defect clusters within individual cascades.

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On the lower energy limit of electronic stopping in simulated collision cascades in Ni, Pd and Pt

Cited by 32 publications

References 31 publications

Electron Elevator: Excitations across the Band Gap via a Dynamical Gap State

Electron Elevator: Excitations across the Band Gap via a Dynamical Gap State

Non-equilibrium properties of interatomic potentials in cascade simulations in tungsten

Direct observation of the spatial distribution of primary cascade damage in tungsten

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