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Defect accumulation in ThO2 irradiated with swift heavy ions

Tracy, Cameron L. and McLain Pray, J. and Lang, Maik and Popov, Dmitry and Park, Changyong and Trautmann, Christina and Ewing, Rodney C. (2014):
Defect accumulation in ThO2 irradiated with swift heavy ions.
In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier Science Publishing, pp. 169-173, 326, ISSN 0168583X,
[Online-Edition: http://dx.doi.org/10.1016/j.nimb.2013.08.070],
[Article]

Abstract

Polycrystalline ThO2 was irradiated with 2.2 GeV Au ions and characterized by synchrotron X-ray diffraction, X-ray absorption spectroscopy, and Raman spectroscopy. The diffraction measurements indicated an increase in the unit cell parameter and the accumulation of heterogeneous microstrain with increasing ion fluence, both of which are consistent with a single-impact model of damage accumulation. An analytical fit of the data to a single-impact model yielded a saturation unit cell expansion of 0.049 ± 0.002% and a saturation strain of 10.4 ± 0.2%. Cross-section data determined from the model values yielded effective ion track diameters of 1.9 ± 0.2 nm and 3.2 ± 0.3 nm for the two modifications, respectively, indicating that the tracks consist of a core region in which swelling and strain have occurred and a defect-rich halo in which microstrain is present but the initial unit cell parameter has not changed significantly. The spectroscopic analysis revealed the presence of significant local structural distortion in the irradiated material, but no evidence of systematic modification to the electronic state or chemical environment of the cations. This indicates that swift heavy ion irradiation of ThO2 primarily produces simple point defects or defect agglomerates.

Item Type: Article
Erschienen: 2014
Creators: Tracy, Cameron L. and McLain Pray, J. and Lang, Maik and Popov, Dmitry and Park, Changyong and Trautmann, Christina and Ewing, Rodney C.
Title: Defect accumulation in ThO2 irradiated with swift heavy ions
Language: English
Abstract:

Polycrystalline ThO2 was irradiated with 2.2 GeV Au ions and characterized by synchrotron X-ray diffraction, X-ray absorption spectroscopy, and Raman spectroscopy. The diffraction measurements indicated an increase in the unit cell parameter and the accumulation of heterogeneous microstrain with increasing ion fluence, both of which are consistent with a single-impact model of damage accumulation. An analytical fit of the data to a single-impact model yielded a saturation unit cell expansion of 0.049 ± 0.002% and a saturation strain of 10.4 ± 0.2%. Cross-section data determined from the model values yielded effective ion track diameters of 1.9 ± 0.2 nm and 3.2 ± 0.3 nm for the two modifications, respectively, indicating that the tracks consist of a core region in which swelling and strain have occurred and a defect-rich halo in which microstrain is present but the initial unit cell parameter has not changed significantly. The spectroscopic analysis revealed the presence of significant local structural distortion in the irradiated material, but no evidence of systematic modification to the electronic state or chemical environment of the cations. This indicates that swift heavy ion irradiation of ThO2 primarily produces simple point defects or defect agglomerates.

Journal or Publication Title: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
Volume: 326
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Ion irradiation, Actinides, Oxides, Diffraction, Spectroscopy
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Ion-Beam-Modified Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 09 Jan 2015 13:16
Official URL: http://dx.doi.org/10.1016/j.nimb.2013.08.070
Additional Information:

17th International Conference on Radiation Effects in Insulators (REI)

Identification Number: doi:10.1016/j.nimb.2013.08.070
Funders: This work was supported by the Energy Frontier Research Center Materials Science of Actinides funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (DE-SC0001089)., HPCAT operations are supported by DOE-NNSA under Award No. DE-NA0001974 and DOE-BES under Award No. DE-FG02-99ER45775, with partial instrumentation funding by NSF., APS is supported by DOE-BES, under Contract No. DE-AC02-06CH11357.
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