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Phase transformations inLn2O3materials irradiated with swift heavy ions

Tracy, Cameron L. and Lang, Maik and Zhang, Fuxiang and Trautmann, Christina and Ewing, Rodney C. (2015):
Phase transformations inLn2O3materials irradiated with swift heavy ions.
In: Physical Review B, American Physical Society, 92, (17), ISSN 1098-0121,
[Online-Edition: http://dx.doi.org/10.1103/PhysRevB.92.174101],
[Article]

Abstract

Phase transformations induced in the cubic C-type lanthanide sesquioxides, Ln(2)O(3) (Ln = Sm, Gd, Ho, Tm, and Lu), by dense electronic excitation are investigated. The structural modifications resulting from exposure to beams of 185 MeV Xe and 2246 MeV Au ions are characterized using synchrotron x-ray diffraction and Raman spectroscopy. The formation of a B-type polymorph, an X-type nonequilibrium phase, and an amorphous phase are observed. The specific phase formed and the transformation rate show dependence on the material composition, as well as the ion beam mass and energy. Atomistic mechanisms for these transformations are determined, indicating that formation of the B-type phase results from the production of anti-Frenkel defects and the aggregation of anion vacancies into planar clusters, whereas formation of the X-type and amorphous phases requires extensive displacement of both anions and cations. The observed variations in phase behavior with changing lanthanide ionic radius and deposited electronic energy density are related to the energetics of these transformation mechanisms.

Item Type: Article
Erschienen: 2015
Creators: Tracy, Cameron L. and Lang, Maik and Zhang, Fuxiang and Trautmann, Christina and Ewing, Rodney C.
Title: Phase transformations inLn2O3materials irradiated with swift heavy ions
Language: English
Abstract:

Phase transformations induced in the cubic C-type lanthanide sesquioxides, Ln(2)O(3) (Ln = Sm, Gd, Ho, Tm, and Lu), by dense electronic excitation are investigated. The structural modifications resulting from exposure to beams of 185 MeV Xe and 2246 MeV Au ions are characterized using synchrotron x-ray diffraction and Raman spectroscopy. The formation of a B-type polymorph, an X-type nonequilibrium phase, and an amorphous phase are observed. The specific phase formed and the transformation rate show dependence on the material composition, as well as the ion beam mass and energy. Atomistic mechanisms for these transformations are determined, indicating that formation of the B-type phase results from the production of anti-Frenkel defects and the aggregation of anion vacancies into planar clusters, whereas formation of the X-type and amorphous phases requires extensive displacement of both anions and cations. The observed variations in phase behavior with changing lanthanide ionic radius and deposited electronic energy density are related to the energetics of these transformation mechanisms.

Journal or Publication Title: Physical Review B
Volume: 92
Number: 17
Publisher: American Physical Society
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: 29 Feb 2016 12:41
Official URL: http://dx.doi.org/10.1103/PhysRevB.92.174101
Identification Number: doi:10.1103/PhysRevB.92.174101
Funders: This paper was supported by the Energy Frontier Research Center Materials Science of Actinides funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (Grant No. DE-SC0001089)., C.L.T. acknowledges support from the National Science Foundation (NSF) Graduate Research Fellowship Program under Grant No. DGE-1256260., The use of the National Synchrotron Light Source at X17C station is supported by NSF COMPRES Cooperative Agreement Grant No. EAR01-35554 and by U.S. DOE Contract No. DE-AC02-10886.
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