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Surface atomic relaxation and magnetism on hydrogen-adsorbed Fe(110) surfaces from first principles

  • We have computed adsorption energies, vibrational frequencies, surface relaxation and buckling for hydrogen adsorbed on a body-centred-cubic Fe(110) surface as a function of the degree of H coverage. This adsorption system is important in a variety of technological processes such as the hydrogen embrittlement in ferritic steels, which motivated this work, and the Haber–Bosch process. We employed spin-polarised density functional theory to optimise geometries of a six-layer Fe slab, followed by frozen mode finite displacement phonon calculations to compute Fe–H vibrational frequencies. We have found that the quasi-threefold (3f) site is the most stable adsorption site, with adsorption energies of ∼3.0 eV/H for all coverages studied. The long-bridge (lb) site, which is close in energy to the 3f site, is actually a transition state leading to the stable 3f site. The calculated harmonic vibrational frequencies collectively span from 730 to 1220 cm−1, for a range of coverages. The increased first-to-second layer spacing in the presence of adsorbed hydrogen, and the pronounced buckling observed in the Fe surface layer, may facilitate the diffusion of hydrogen atoms into the bulk, and therefore impact the early stages of hydrogen embrittlement in steels.

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Metadaten
Author:Urslaan Chohan, Enrique Jimenez-Melero, Sven P. K. KöhlerORCiD
URN:urn:nbn:de:bsz:960-opus4-22747
DOI:https://doi.org/10.25968/opus-2274
DOI original:https://doi.org/10.1016/j.apsusc.2016.06.027
ISSN:0169-4332
Parent Title (English):Applied Surface Science
Publisher:Elsevier
Document Type:Article
Language:English
Year of Completion:2016
Publishing Institution:Hochschule Hannover
Release Date:2022/05/31
Tag:Adsorption; Density functional theory; Ferritic steels; Haber–Bosch process; Hydrogen embrittlement
GND Keyword:Ferritischer Stahl; Wasserstoffversprödung; Dichtefunktionalformalismus; Adsorption; Haber-Bosch-Verfahren
Volume:387
First Page:385
Last Page:392
Link to catalogue:1805890816
Institutes:Fakultät II - Maschinenbau und Bioverfahrenstechnik
DDC classes:660 Technische Chemie
Licence (German):License LogoCreative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 4.0 International