Electronic stopping power dependence of ion-track size in UO2 irradiated with heavy ions in the energy range of ∼1MeV/u

Ishikawa, N.; Sonoda, Tatsuhiko; Sawabe, Takashi; Sugai, H.; Sataka, M.

doi:10.1016/j.nimb.2013.05.038

Cited by 28 publications

(10 citation statements)

References 16 publications

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“…For all stopping powers tested the number of defects and the resulting track radii calculated using C e (T e ) from the free electron gas model are substantially greater than when using C e (T e ) determined via DFT. Figure 6b suggests that when DFT is used to parameterise the specific heat, the change in the track radius as a function of stopping power reproduces the relationship observed in experimental studies of other semiconductors [5,6,7] and insulators [1,2,3]. The free electron model, on the other hand, shows a linear relationship between track radius and electronic stopping power.…”

Section: Resultssupporting

confidence: 64%

The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon

Khara

Murphy

Daraszewicz

et al. 2016

J. Phys.: Condens. Matter

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Abstract. Swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat.

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Section: Resultssupporting

confidence: 64%

The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon

Khara

Murphy

Daraszewicz

et al. 2016

J. Phys.: Condens. Matter

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“…Fission of uranium atoms produces high-energy "fission fragments" that deposit their energy primarily into the electronic subsystem of UO 2 , producing cylindrical tracks of permanent structural damage that are nanometers wide and microns in length. Notably, the track radii observed in UO 2 are smaller than expected [3], even when compared with materials that have similar thermal and physical properties [3,4]. This has led to different models for the damage process [4,5].…”

Section: Introductionmentioning

confidence: 96%

“…Notably, the track radii observed in UO 2 are smaller than expected [3], even when compared with materials that have similar thermal and physical properties [3,4]. This has led to different models for the damage process [4,5].…”

Section: Introductionmentioning

confidence: 96%

Anomalous behavior of nonequilibrium excitations in UO2

et al. 2019

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Ultrafast optical pump-probe studies of uranium dioxide (UO 2) under pressure were performed in order to better understand the material's response to ionizing radiation. Photoexcitation generates oscillations in the time-resolved reflectivity at two distinct GHz-scale frequencies. The higher frequency mode is attributed to a coherent longitudinal acoustic mode. The lower frequency mode does not correspond to any known excitation under equilibrium conditions. The frequency and lifetime of the low-frequency mode are studied as a function of pressure. Abrupt changes in the pressure-dependent slopes of these attributes are observed at ~10 GPa, which correlates with an electronic transition in UO 2. Variation of probe wavelength reveals that the low k dispersion of the low-frequency mode does not fit into either an optical or acoustic framework. Rather, we propose that this mode is related to the dynamical magnetic structure of UO 2. The implications of these results help account for the anomalously small volume of damage known to be caused by ionizing radiation in UO 2 ; we propose that the existence of the low-frequency mode enhances the material's transient thermal conductivity, while its long lifetime lengthens the timescale over which energy is dissipated. Both mechanisms enhance damage recovery.

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“…Ion track formation in uranium oxide (UO 2 ) is particular important for light water reactors, due to the facts that fission fragments from neutron reactions, in a typical kinetic energy of 100 MeV, may lead to structural changes which cause thermal and mechanical property degradation, and influence reactor performance. Experiments on both accelerator based swift ion irradiations and reactor irradiation have observed ion track formation in UO 2 [13,14]. Computer simulations have been used to understand CE effects [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Melting and shock wave creation in uranium oxide due to Coulomb explosion after a pulsed ionization

Chen

Shao

2015

Nuclear Instruments and Methods in Physics Research Section B:

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Electronic stopping power dependence of ion-track size in UO2 irradiated with heavy ions in the energy range of ∼1MeV/u

Cited by 28 publications

References 16 publications

The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon

The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon

Anomalous behavior of nonequilibrium excitations in UO2

Melting and shock wave creation in uranium oxide due to Coulomb explosion after a pulsed ionization

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