Magnetocrystalline effects on the subsurface hydrogen diffusion in γ-Fe(0 0 1)

U. K. Chohan; E. Jimenez-Melero; S. P.K. Koehler

doi:10.1016/j.commatsci.2018.06.025

Magnetocrystalline effects on the subsurface hydrogen diffusion in γ-Fe(0 0 1)

U. K. Chohan, E. Jimenez-Melero^*, S. P.K. Koehler

^*Corresponding author for this work

Metallurgy and Materials

Research output: Contribution to journal › Article › peer-review

Abstract

The effect of magnetism on hydrogen adsorption and subsurface diffusion through face-centred cubic (fcc) γ-Fe(0 0 1) was investigated using spin-polarised density functional theory (s-DFT). The non-magnetic (NM), ferromagnetic (FM), and antiferromagnetic single (AFM1) and double layer (AFMD) structures were considered. For each magnetic state, the hydrogen preferentially adsorbs at the fourfold site, with adsorption energies of 4.07, 4.12, 4.03 and 4.05 eV/H atom for the NM, FM, AFM1 and AFMD structures. A total barrier of 1.34, 0.90, 1.32 and 1.25 eV and a bulk-like diffusion barrier of 0.6, 0.2, 0.4 and 0.3 eV were calculated for the NM, FM, AFM1 and AFMD magnetic states. The Fe atoms nearest to the H atom exhibited a reduced magnetic moment, whereas the next-nearest neighbour Fe atoms exhibited a non-negligible local perturbation in the magnetic moment. The presence of magnetically ordered structures has a minimal influence on the minimum energy path for H diffusion through the lattice and on the adsorption of H atoms on the Fe(0 0 1) surface, but we computed a significant reduction of the bulk-like diffusion barriers with respect to the non-magnetic state of fcc γ-Fe.

Original language	English
Pages (from-to)	57-63
Number of pages	7
Journal	Computational Materials Science
Volume	153
DOIs	https://doi.org/10.1016/j.commatsci.2018.06.025
Publication status	Published - Oct 2018

Bibliographical note

We would like express our appreciation to the Engineering and Physical Sciences Research Council UK via the Centre for Doctoral Training in Advanced Metallic Systems for their financial support (EP/L016273/1). We thank the Dalton Cumbrian Facility, partly funded by the Nuclear Decommissioning Authority, for funding the cost of computational time.

Keywords

Density functional theory
Gamma iron
Hydrogen diffusion
Magnetism

ASJC Scopus subject areas

General Computer Science
General Chemistry
General Materials Science
Mechanics of Materials
General Physics and Astronomy
Computational Mathematics

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10.1016/j.commatsci.2018.06.025

Cite this

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title = "Magnetocrystalline effects on the subsurface hydrogen diffusion in γ-Fe(0 0 1)",

abstract = "The effect of magnetism on hydrogen adsorption and subsurface diffusion through face-centred cubic (fcc) γ-Fe(0 0 1) was investigated using spin-polarised density functional theory (s-DFT). The non-magnetic (NM), ferromagnetic (FM), and antiferromagnetic single (AFM1) and double layer (AFMD) structures were considered. For each magnetic state, the hydrogen preferentially adsorbs at the fourfold site, with adsorption energies of 4.07, 4.12, 4.03 and 4.05 eV/H atom for the NM, FM, AFM1 and AFMD structures. A total barrier of 1.34, 0.90, 1.32 and 1.25 eV and a bulk-like diffusion barrier of 0.6, 0.2, 0.4 and 0.3 eV were calculated for the NM, FM, AFM1 and AFMD magnetic states. The Fe atoms nearest to the H atom exhibited a reduced magnetic moment, whereas the next-nearest neighbour Fe atoms exhibited a non-negligible local perturbation in the magnetic moment. The presence of magnetically ordered structures has a minimal influence on the minimum energy path for H diffusion through the lattice and on the adsorption of H atoms on the Fe(0 0 1) surface, but we computed a significant reduction of the bulk-like diffusion barriers with respect to the non-magnetic state of fcc γ-Fe.",

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author = "Chohan, {U. K.} and E. Jimenez-Melero and Koehler, {S. P.K.}",

note = "We would like express our appreciation to the Engineering and Physical Sciences Research Council UK via the Centre for Doctoral Training in Advanced Metallic Systems for their financial support (EP/L016273/1). We thank the Dalton Cumbrian Facility, partly funded by the Nuclear Decommissioning Authority, for funding the cost of computational time.",

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AU - Chohan, U. K.

AU - Jimenez-Melero, E.

AU - Koehler, S. P.K.

N1 - We would like express our appreciation to the Engineering and Physical Sciences Research Council UK via the Centre for Doctoral Training in Advanced Metallic Systems for their financial support (EP/L016273/1). We thank the Dalton Cumbrian Facility, partly funded by the Nuclear Decommissioning Authority, for funding the cost of computational time.

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N2 - The effect of magnetism on hydrogen adsorption and subsurface diffusion through face-centred cubic (fcc) γ-Fe(0 0 1) was investigated using spin-polarised density functional theory (s-DFT). The non-magnetic (NM), ferromagnetic (FM), and antiferromagnetic single (AFM1) and double layer (AFMD) structures were considered. For each magnetic state, the hydrogen preferentially adsorbs at the fourfold site, with adsorption energies of 4.07, 4.12, 4.03 and 4.05 eV/H atom for the NM, FM, AFM1 and AFMD structures. A total barrier of 1.34, 0.90, 1.32 and 1.25 eV and a bulk-like diffusion barrier of 0.6, 0.2, 0.4 and 0.3 eV were calculated for the NM, FM, AFM1 and AFMD magnetic states. The Fe atoms nearest to the H atom exhibited a reduced magnetic moment, whereas the next-nearest neighbour Fe atoms exhibited a non-negligible local perturbation in the magnetic moment. The presence of magnetically ordered structures has a minimal influence on the minimum energy path for H diffusion through the lattice and on the adsorption of H atoms on the Fe(0 0 1) surface, but we computed a significant reduction of the bulk-like diffusion barriers with respect to the non-magnetic state of fcc γ-Fe.

AB - The effect of magnetism on hydrogen adsorption and subsurface diffusion through face-centred cubic (fcc) γ-Fe(0 0 1) was investigated using spin-polarised density functional theory (s-DFT). The non-magnetic (NM), ferromagnetic (FM), and antiferromagnetic single (AFM1) and double layer (AFMD) structures were considered. For each magnetic state, the hydrogen preferentially adsorbs at the fourfold site, with adsorption energies of 4.07, 4.12, 4.03 and 4.05 eV/H atom for the NM, FM, AFM1 and AFMD structures. A total barrier of 1.34, 0.90, 1.32 and 1.25 eV and a bulk-like diffusion barrier of 0.6, 0.2, 0.4 and 0.3 eV were calculated for the NM, FM, AFM1 and AFMD magnetic states. The Fe atoms nearest to the H atom exhibited a reduced magnetic moment, whereas the next-nearest neighbour Fe atoms exhibited a non-negligible local perturbation in the magnetic moment. The presence of magnetically ordered structures has a minimal influence on the minimum energy path for H diffusion through the lattice and on the adsorption of H atoms on the Fe(0 0 1) surface, but we computed a significant reduction of the bulk-like diffusion barriers with respect to the non-magnetic state of fcc γ-Fe.

KW - Density functional theory

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Magnetocrystalline effects on the subsurface hydrogen diffusion in γ-Fe(0 0 1)

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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Magnetocrystalline effects on the subsurface hydrogen diffusion in γ-Fe(0 0 1)