Atomic diffusion mechanism of Xe in UO2 |
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Authors: | Younsuk Yun Hanchul Kim Heemoon Kim Kwangheon Park |
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Affiliation: | aDepartment of Physics and Materials Science, Box 530, Uppsala University, S-75121 Uppsala, Sweden;bDepartment of Physics, Sookmyung Women’s University, Seoul 140-702, Republic of Korea;cKorea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-353, Republic of Korea;dDepartment of Nuclear Engineering, KyungHee University, Suwon 449-701, Republic of Korea |
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Abstract: | We have investigated vacancy-assisted diffusion of Xe in uranium dioxide (UO2) calculating incorporation, binding, and migration energies. All the energy values have been obtained using the density functional theory (DFT) within the generalized gradient approximation (GGA) and the projector-augmented-wave (PAW) method. Considering spin-polarization effect, we find that the computed migration energy is reduced by and agrees well with experimental data compared to those obtained from non-magnetic calculations. We also find that an oxygen vacancy lowers the migration energy of a uranium vacancy by about 1 eV, enhancing an effective movement of vacancy clusters consisting of both uranium and oxygen vacancies. Furthermore, the strain energy of Xe is large enough to contribute to the clustering of vacancies making it the driving force for the vacancy-assisted diffusion of Xe in UO2. In summary all the calculated results suggest that the trivacancy is a major diffusion pathway of Xe in UO2. |
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Keywords: | 61.72.Ji 66.30.Jt |
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