LaNi5中C、H间隙原子间相互作用的第一性原理研究-中国材料进展

文章信息/Info

Title:: Interactions of Carbon and Hydrogen Interstitial Atoms in LaNi5: A First-Principles Study

Author(s):: XIANG Xin; YANG Feilong; HU Li; SONG Yaqi; ZHU Hongzhi; Institute of Materials，China Academy of Engineering Physics，Jiangyou 621908，China

摘要:: LaNi5合金因其优良的综合性能，如吸氢容量大、吸/放氢快、平衡离解压适中等，在氢能及氢同位素工艺等领域得到了广泛的应用。然而，LaNi5合金中间隙杂质如C、H等的相互作用机制尚不明确。采用第一性原理计算研究了LaNi5中C、H间隙原子的占位、形成能、迁移行为及二者间的相互影响。从形成能及原子构型来看，LaNi5中C、H原子的稳定占位分别是2d和12n间隙位。因原子半径更小及更低的形成能和迁移势垒，LaNi5中间隙H原子比间隙C原子更易形成和迁移。LaNi5中C、H间隙原子间存在明显的相互作用。具体来讲，LaNi5中的间隙C、H原子将分别因H、C原子的引入更易形成，但其迁移能力将变差。上述研究结果对LaNi5合金中C杂质的提纯、控制及含C杂质气体形成机理的认识有重要的指导意义。

Abstract:: LaNi5 alloys are widely used in the fields of hydrogen energy and hydrogen isotope technology for their excellent comprehensive performances, such as high hydrogen absorption capacity, fast absorption/desorption kinetics, moderate equilibrium dissociation pressure, etc. However, the interaction mechanism of interstitial impurities such as C and H in LaNi5 is still unclear. The occupancy, formation energies, migration behaviors of C and H interstitial atoms and interactions between C and H interstitial atoms in LaNi5 have been thus investigated via first-principles calculations. From the view of formation energy and atomic configuration, the stable occupying site of C and H interstitial atoms in LaNi5 is 2d and 12n site, respectively. An interstitial H atom is more readily to form and migrate than C in LaNi5 for its smaller atomic size, and much lower formation energy and migration barrier. Obvious interactions between C and H interstitial atoms present in LaNi5. Specifically, the C or H interstitial atom in LaNi5 is more readily to form separately with the addition of H or C atom, while the individual migration ability will get worse. The obtained results may be instructive for the purification and control of C impurity and the understanding of the formation mechanism of C containing gas in LaNi5 alloys.