Ab initio study of helium in α-Fe:: Dissolution, migration, and clustering with vacancies -: art. no. 064117
Ab initio study of helium in α-Fe:: Dissolution, migration, and clustering with vacancies -: art. no. 064117
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DOI：
10.1103/physrevb.72.064117
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发表时间：
2005-08-01
影响因子：
3.7
通讯作者：
Willaime, F
中科院分区：
文献类型：
--
作者：
Fu, CC;Willaime, F
用密度泛函理论研究了氦在α-铁中的溶解和迁移，以及氦空位团簇HenVm（n，m=0 ~ 4）的稳定性.氦的替代和填隙构型被发现具有相似的稳定性。四面体构型比八面体稳定0.2 eV。间隙氦原子被预测有吸引力的相互作用和一个非常低的迁移能量（0.06 eV），这表明他气泡可以在低温下形成在最初的无空位晶格。由空位机制的替代氦的迁移由HeV 2络合物的迁移所支配，具有1.1 eV的能垒。氦扩散的解离和空缺机制的活化能估计的热空缺制度和高过饱和度的空缺的极限情况下。空位和氦的氦空位团簇的结合能的趋势进行了讨论，提供额外的知识，他在辐照铁的行为，必要的复杂的实验数据，如热氦解吸光谱的解释。
Density functional theory calculations have been performed to study the dissolution and migration of helium in alpha-iron, and the stability of small helium-vacancy clusters HenVm (n,m=0 to 4). Substitutional and interstitial configurations of helium are found to have similar stabilities. The tetrahedral configuration is more stable than the octahedral by 0.2 eV. Interstitial helium atoms are predicted to have attractive interactions and a very low migration energy (0.06 eV), suggesting that He bubbles can form at low temperatures in initially vacancy-free lattices. The migration of substitutional helium by the vacancy mechanism is governed by the migration of the HeV2 complex, with an energy barrier of 1.1 eV. The activation energies for helium diffusion by the dissociation and vacancy mechanisms are estimated for the limiting cases of thermal-vacancy regime and of high supersaturation of vacancies. The trends of the binding energies of vacancy and helium to helium-vacancy clusters are discussed in terms of providing additional knowledge on the behavior of He in irradiated iron, necessary for the interpretation of complex experimental data such as thermal He desorption spectra.