کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1295439 | 1498276 | 2014 | 5 صفحه PDF | دانلود رایگان |
• Lowest energy vacancy migration requires reconfiguration of lowest energy cluster.
• Charge balancing defects have a major effect on activation energy barrier.
• Many configurations have more favourable migrations than the low energy cluster.
• Stoichiometry has a major effect on the number of possible cluster arrangements.
• The number of possible migration mechanisms affects Arrhenius pre-exponential term.
The effect of cluster configuration on vacancy mediated uranium migration is investigated for stoichiometric UO2 and hyper-stoichiometric UO2+x. The minimum enthalpy pathway involves reconfiguration of the most stable cluster to a metastable configuration, in stoichiometric and hyper-stoichiometric systems. Additionally, a much larger number of alternative metastable configurations were identified for UO2+x compared to UO2. This would lead to a larger contribution to the Arrhenius pre-exponential term with hyper-stoichiometry. Consequently, the often made assumption that re-orientation of the ground state cluster offers access to the migration activation energy cannot be assumed to be valid.
Journal: Solid State Ionics - Volume 266, 15 November 2014, Pages 68–72