Molecular dynamics simulation of helium and oxygen diffusion in
| Autor: | Sergei Lemehov, Kevin Govers, Marc Verwerft, Marc Hou |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Nuclear and High Energy Physics
Work (thermodynamics) chemistry.chemical_element Activation energy Atmospheric temperature range Atomic units Nuclear physics Molecular dynamics Nuclear Energy and Engineering chemistry Chemical physics General Materials Science Diffusion (business) Helium Stoichiometry |
| Zdroj: | Journal of Nuclear Materials. 395:131-139 |
| ISSN: | 0022-3115 |
| DOI: | 10.1016/j.jnucmat.2009.10.043 |
| Popis: | Atomic scale simulation techniques based on empirical potentials have been considered in the present work to get insight on helium diffusion in uranium dioxide. By varying the stoichiometry, together with the system temperature, the performed molecular dynamics simulations indicate two diffusion regimes for He. The first one presents a low activation energy (0.5 eV) and suggests oxygen vacancies assisted migration. This regime seems to provide the major contribution to diffusion when structural defects are present (extrinsic defects, imposed, e.g. by the stoichiometry). The second regime presents a higher activation energy, around 2 eV, and dominates in the higher temperature range or at perfect stoichiometry, suggesting an intrinsic migration process. Considering the dependance of He behaviour with oxygen defects, oxygen diffusion has been considered as well in the different stoichiometry domains. Finally, further investigations were made with nudged elastic bands calculations for a better interpretation of the operating migration mechanisms, both for He and O. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect