Electronic excitation effects in CeO2 under irradiations with high-energy ions of typical fission products

Sonoda, Tatsuhiko; Kinoshita, Motoyasu; Chimi, Y.; Ishikawa, N.; Sataka, M.; Iwase, A.

doi:10.1016/j.nimb.2006.04.120

Cited by 73 publications

(38 citation statements)

References 7 publications

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“…This threshold was not dependent on irradiation temperature up to 800 ºC. The observed diameter by TEM ranged from 9 nm at RT to 7 nm at 800 ºC at surface of the specimen, depending on irradiation temperature [8].…”

Section: (2) Swift Heavy Ion Irradiationmentioning

confidence: 81%

Recovery and restructuring induced by fission energy ions in high burnup nuclear fuel

Kinoshita

Yasunaga

Sonoda

et al. 2009

Nuclear Instruments and Methods in Physics Research Section B:

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In light water commercial reactors, extensive change of grain structure was found at high burnup ceramic fuels. The mechanism is driven by bombardment of fission energy fragments and studies were conducted by combining accelerator based experiments and computer science. Specimen of CeO 2 was used as simulation material of fuel ceramics. With swift heavy ion (Xe) irradiation on CeO 2 , with 210 MeV, change of valence charge and lattice deviation of cations were observed by XPS and XRD. Combined irradiations of Xe implantation and swift heavy ion irradiation successfully produced sub-micrometer sized subgrains, similar as that observed in commercial fuels. Studying components of mechanism scenarios, with first principle calculations using the VASP code, we found stable hyperstoichiometric defect structures of UO 2+x . Molecular dynamics studies revealed stability of Xe planar defects and also found rapid transport mode of oxygen-vacancy clusters.

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Section: (2) Swift Heavy Ion Irradiationmentioning

confidence: 81%

Recovery and restructuring induced by fission energy ions in high burnup nuclear fuel

Kinoshita

Yasunaga

Sonoda

et al. 2009

Nuclear Instruments and Methods in Physics Research Section B:

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“…At such high fluences, both CeO 2 (refs 61,62) and UO 2 (refs 12,63) are known to undergo extensive microstructural modification under fission fragment irradiation, developing nanocrystalline subgrains and porosity. Termed the 'rim effect', this process is commonly encountered in the relatively cool outer region of fuel pellets where fission rates are highest, and has been attributed to the formation of a dislocation loop network 12,[61][62][63] . The precipitation of anion interstitial defects into these dislocation loops has been observed in CeO 2 (ref.…”

Section: Discussionmentioning

confidence: 99%

Redox response of actinide materials to highly ionizing radiation

et al. 2015

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Energetic radiation can cause dramatic changes in the physical and chemical properties of actinide materials, degrading their performance in fission-based energy systems. As advanced nuclear fuels and wasteforms are developed, fundamental understanding of the processes controlling radiation damage accumulation is necessary. Here we report oxidation state reduction of actinide and analogue elements caused by high-energy, heavy ion irradiation and demonstrate coupling of this redox behaviour with structural modifications. ThO 2 , in which thorium is stable only in a tetravalent state, exhibits damage accumulation processes distinct from those of multivalent cation compounds CeO 2 (Ce 3 þ and Ce 4 þ ) and UO 3 (U 4 þ , U 5 þ and U 6 þ ). The radiation tolerance of these materials depends on the efficiency of this redox reaction, such that damage can be inhibited by altering grain size and cation valence variability. Thus, the redox behaviour of actinide materials is important for the design of nuclear fuels and the prediction of their performance.

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“…Analyzing tracks in CaF 2 will help to better understand response to swift heavy ions and specific damage phenomena in other nonamorphizable crystals with the fluorite structure. This concerns, for instance, UO 2 65,66 (or CeO 2 as a surrogate [80][81][82] ), a nuclear material that has to withstand high dose radiation from fission fragments.…”

Section: Track Formation In Cafmentioning

confidence: 99%

Dense and nanometric electronic excitations induced by swift heavy ions in an ionic CaF2crystal: Evidence for two thresholds of damage creation

et al. 2012

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CaF 2 crystals as representatives of the class of ionic nonamorphizable insulators were irradiated with many different swift heavy ions of energy above 0.5 MeV/u providing a broad range of electronic energy losses (S e ). Beam-induced modifications were characterized by Channeling Rutherford Backscattering Spectrometry (C-RBS) and x-ray diffraction (XRD), complemented by transmission electron microscopy (TEM). Results from C-RBS give evidence of significant damage appearing above a S e threshold of 5 ± 2 keV/nm. A second critical S e appears around 18 ± 3 keV/nm; below this value the damage as function of ion fluence saturates at 20%, while above this the damage saturation level increases with S e , reaching ∼60% for ions of S e = 30 keV/nm. XRD measurements also show effects indicating two threshold values. Above 5 keV/nm, the widths of the XRD reflection peaks increase due to the formation of nanograins, as seen by TEM, while a significant decrease of the peak areas only occurs above 18 keV/nm. The track radii deduced from C-RBS measurements are in agreement with those extracted from the fluence evolution of the widths of the XRD peaks. Moreover, track radii deduced from the peak area analysis are slightly smaller but in agreement with previous track observations by high resolution electron microscopy. Calculations based on the inelastic thermal spike model suggest that the lower threshold at 5 keV/nm is linked to the quenching of the molten phase, whereas the threshold at 18 keV/nm can be interpreted as quenching of the boiling phase. The results of CaF 2 are compared with other nonamorphizable materials such as LiF and UO 2 .

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Electronic excitation effects in CeO2 under irradiations with high-energy ions of typical fission products

Cited by 73 publications

References 7 publications

Recovery and restructuring induced by fission energy ions in high burnup nuclear fuel

Recovery and restructuring induced by fission energy ions in high burnup nuclear fuel

Redox response of actinide materials to highly ionizing radiation

Dense and nanometric electronic excitations induced by swift heavy ions in an ionic CaF2crystal: Evidence for two thresholds of damage creation

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