摘要
应用第一性原理密度泛函理论系统研究氧、氢和碳原子在α-铀(001)表面的吸附与扩散特性。研究发现:在铀表面氧原子与氢原子择优吸附在H2位置,碳原子倾向于占据在H1位置;氧原子在铀表面的扩散势垒较低,容易在铀表面上扩散,形成表面氧化层;氢原子的扩散势垒较高,碳原子的扩散势垒最大,难以在表面扩散。吸附原子从铀表面向次表面层扩散时,氧原子的扩散势垒很高,难以向次表面扩散;碳和氢原子的扩散势垒较低,特别是在氧的辅助作用下,碳原子向次表面的扩散势垒降低约0.5 eV,使碳原子易于向次表面层扩散;铀表面上会形成氧化层,次表面会形成富碳层,可对铀的进一步氧化起到抑制作用,这与相关实验结果符合较好。
The adsorption and diffusion properties of O, H and C atoms on α-U（001） surface were studied by first-principles density functional theory approach. For the on-surface adsorption, O and H atoms prefer to occupy the H2 site, while C atoms tend to occupy the H1 site. The diffusion barrier of O atom on U surface is low and the diffusion is easy, which will lead to the formation of uranium-oxidation layer on the top of surface. The diffusion barrier of H atom is larger and that of C atom is the largest one, thus it is difficult for C atom diffusion on the U surface. As for the diffusion of atom from the surface site to the sub-surface, the barriers of H and C atoms are low, while that of O atom is very high, which indicates that the O atom can not migrate into the next surface. And the barrier of C atom diffusion to the sub-surface is reduced by about 0.5 eV with the assistance of O atom nearby. The U-O oxidation layer on the surface and the U-C layer on the sub-surface can be formed easily, which help to prevent the metallic U from further oxidation. These results agree good with available experiments.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2013年第4期1160-1167,共8页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(10976009)
关键词
α-铀
第一性原理
表面吸附
扩散势垒
α-uranium
first-principles
surface adsorption
diffusion barrier
