First-principles study of the crystal structures and electronic properties of LaNi5TxHey tritide

The micro-arrangement of helium atoms and electronic properties of tritides LaNi5TxHey (x=5, 5.5, 6, 6.5; y=0.5, 1.0) have been systematically investigated by means of the full-potential linearized augmented plane wave (FLAPW) method with the generalized gradient approximation (GGA). Those optimized results indicate that helium atoms prefer to occupy the tetrahedral interstitial sites (6c1) in LaNi5 tritides. From the analysis of the electronic structure, a strong and narrow peak appears in the low energy region (about −4.0 eV), which is due to the contribution of the He–s band. With increasing in the helium content, the empty band in the low energy region gradually moves to the right. Compared with H atoms, the interactions between He atom and La, Ni atoms are quite weaker, which can easily cause the pulverization of the host alloy.