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Swift heavy ion irradiation-induced amorphization of La2Ti2O7

Park, Sulgiye and Lang, Maik and Tracy, Cameron L. and Zhang, Jiaming and Zhang, Fuxiang and Trautmann, Christina and Kluth, Patrick and Rodriguez, Matias D. and Ewing, Rodney C. (2014):
Swift heavy ion irradiation-induced amorphization of La2Ti2O7.
In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Elsevier Science Publishing, pp. 145-149, 326, ISSN 0168583X,
[Online-Edition: http://dx.doi.org/10.1016/j.nimb.2013.10.088],
[Article]

Abstract

Polycrystalline La2Ti2O7 powders have been irradiated with 2.0 GeV 181Ta ions up to a fluence of 1 × 1013 ions/cm2. Radiation-induced structural modifications were analyzed using synchrotron-based X-ray diffraction (XRD), small angle X-ray scattering (SAXS), Raman spectroscopy and transmission electron microscopy (TEM). An increase in the amorphous fraction as a function of fluence was revealed by XRD and Raman analyses and is evidenced by the reduction in intensity of the sharp Bragg maxima from the crystalline regions. Concurrently, diffraction maxima and vibrational absorption bands broaden with the increasing amorphous fraction. The cross-section for the crystalline-to-amorphous transformation (ion tracks) was determined by quantitative analysis of XRD patterns yielding a track diameter of d = 7.2 ± 0.9 nm. Slightly larger track diameters were obtained directly from TEM images (d = 10.6 ± 0.8 nm) and SAXS analysis (d = 10.6 ± 0.3 nm). High-resolution TEM images revealed that single tracks are entirely amorphous without any outer crystalline, disordered shell as found in pyrochlore oxides of the same stoichiometry. The large ratio of ionic radii of the A- and B-site cations (rA/rB = 1.94) means that disordering over the A- and B-sites is energetically unfavorable.

Item Type: Article
Erschienen: 2014
Creators: Park, Sulgiye and Lang, Maik and Tracy, Cameron L. and Zhang, Jiaming and Zhang, Fuxiang and Trautmann, Christina and Kluth, Patrick and Rodriguez, Matias D. and Ewing, Rodney C.
Title: Swift heavy ion irradiation-induced amorphization of La2Ti2O7
Language: English
Abstract:

Polycrystalline La2Ti2O7 powders have been irradiated with 2.0 GeV 181Ta ions up to a fluence of 1 × 1013 ions/cm2. Radiation-induced structural modifications were analyzed using synchrotron-based X-ray diffraction (XRD), small angle X-ray scattering (SAXS), Raman spectroscopy and transmission electron microscopy (TEM). An increase in the amorphous fraction as a function of fluence was revealed by XRD and Raman analyses and is evidenced by the reduction in intensity of the sharp Bragg maxima from the crystalline regions. Concurrently, diffraction maxima and vibrational absorption bands broaden with the increasing amorphous fraction. The cross-section for the crystalline-to-amorphous transformation (ion tracks) was determined by quantitative analysis of XRD patterns yielding a track diameter of d = 7.2 ± 0.9 nm. Slightly larger track diameters were obtained directly from TEM images (d = 10.6 ± 0.8 nm) and SAXS analysis (d = 10.6 ± 0.3 nm). High-resolution TEM images revealed that single tracks are entirely amorphous without any outer crystalline, disordered shell as found in pyrochlore oxides of the same stoichiometry. The large ratio of ionic radii of the A- and B-site cations (rA/rB = 1.94) means that disordering over the A- and B-sites is energetically unfavorable.

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: Swift heavy ion irradiation, La2Ti2O7, Pyrochlore, Perovskite
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: 12 Jan 2015 12:38
Official URL: http://dx.doi.org/10.1016/j.nimb.2013.10.088
Additional Information:

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

Identification Number: doi:10.1016/j.nimb.2013.10.088
Funders: This work was supported by the Center for the Materials Science of Actinides, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Basic Energy Sciences (DE-SC0001089). , The use of CHESS beam is supported by NSF & NIH/NIGMS via NSF award DMR-0225180., TEM instrumentation at the Electron Micro-beam Analysis Laboratory at the University of Michigan is supported by NSF Grants DMR-987177 and DMR-0723032., P.K. acknowledges the Australian Research Council for financial support.
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