CAJ | 학술논문

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.
응용제일성원리밀도범함이론계통연구양、경화탄원자재α-유(001)표면적흡부여확산특성.연구발현:재유표면양원자여경원자택우흡부재 H2위치,탄원자경향우점거재 H1위치;양원자재유표면적확산세루교저,용역재유표면상확산,형성표면양화층;경원자적확산세루교고,탄원자적확산세루최대,난이재표면확산.흡부원자종유표면향차표면층확산시,양원자적확산세루흔고,난이향차표면확산;탄화경원자적확산세루교저,특별시재양적보조작용하,탄원자향차표면적확산세루강저약0.5 eV,사탄원자역우향차표면층확산;유표면상회형성양화층,차표면회형성부탄층,가대유적진일보양화기도억제작용,저여상관실험결과부합교호.
@@@@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.