The effect of interstitial hydrogen on the electronic structure of the B2 FeAl alloy

Abstract

The electronic structure and bonding in a B2 Fe -Al alloy with and without hydrogen as an interstitial atom were studied within the framework of the density functional theory and the findings compared with previous results in Fe an Al. The hydrogen absorption turns out to be a favorable process. The hydrogen was found near an Al octahedral site, the Al -H distance being shorter than that of Fe -H. The density of states (DOS) curves show several peaks below the d metal band which is made up mostly of hydrogen based states (> 50% H 1s ) while the metal contribution includes mainly s-and p-orbitals. An electron transfer of nearby 0.14 e -comes from the metal to the H. The overlap population values reveal metal -metal bond breaking, the intermetallic bond being the most affected. The H bond mainly with the Al atoms and the reported Fe -H overlap population is much lower than that corresponding to FePd alloys and BCC Fe. The changes in the overlap population show the Fe -Al bond is weakening nearly 53% after H absorption, while the Fe -Fe bond is only weakened 23%.

The changes in the electronic structure of B2 FeAl alloy with a Fe antisite and absorbed hydrogen

“…The total DOS for the perfect B2 FeAl structure is similar to that reported previously [9][10][11][12][13][14][15][16][17][18][27][28][29][30][31][32][33][34]. First principles calculations have mentioned the formation of a pseudo-band gap at the top of the 3d band [33,35].…”

“…After H absorption the total DOS shows several small peaks (see Fig. 7) below À12 eV, which is similar to that obtained when H is located as interstitial (O2 site) at a pure cell of B2 FeAl [27]. The most important interaction of H is developed with Al.…”

The hydrogen effect in the electronic structure and bonding of the B2 FeAl alloy with a Fe vacancy

“…The electronic structure of pure FeAl alloy has been previously reported by several researchers and by us [39][40][41][42][43][44]. The introduction of an Fe vacancy does not change the DOS plots in Fig.…”

Interaction of hydrogen and platinum over a B2 FeTi (110) Slab

“…For this, we used the Amsterdam Density Functional package (ADF-DFT) [28]. Further details of the calculations are given in [29,30].…”