Surface coverage dependent mechanisms for the absorption and desorption of hydrogen from the W(1 1 0) and W(1 0 0) surfaces: a density functional theory investigation

Ajmalghan, M; Piazza, Zachary A.; Hodille, E.; Ferro, Y.

doi:10.1088/1741-4326/ab33e7

Cited by 25 publications

(58 citation statements)

References 80 publications

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“…Using this method, we determine the dependence of the desorption energy E D and the absorption energy (the surface into the bulk) E A on hydrogen coverage. For both energies the dependence is similar: they increase as coverage decreases which is in agreement with DFT calculations [17,18].…”

Section: Discussionsupporting

confidence: 88%

“…Sub-surface Bulk ≈ 0.60−0.50 eV; this might appear large as compared to DFT results [18] in which E off−set S does not exceed 0.12 eV on well oriented surfaces. The discrepancy could be explained by the fact that in the present work, we model highly damaged surfaces, which might explain a larger value of E off−set…”

Section: Surfacementioning

confidence: 56%

“…From figure 8, considering the energy profile plotted with the dotted line, E eff S is obviously the solution energy E S . However, this energy profile was recently shown to be distorted in the sub-surface region [18,32] resulting in the profile plotted with solid line in figure 8. As a consequence, an off-set appears between E eff S and the solution energy E S (figure 8):…”

Section: Impact On the Calculation Of The Solution Energymentioning

confidence: 99%

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Kinetic model for hydrogen absorption in tungsten with coverage dependent surface mechanisms

Hodille¹,

Markelj²,

Pečovnik³

et al. 2020

Nucl. Fusion

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In this work, a kinetic model is presented to describe hydrogen absorption and desorption from tungsten at different surface coverages. Activation energies for hydrogen absorption into the bulk and desorption from the surface of tungsten are modelled by functions that depend explicitly and continuously on the hydrogen surface coverage. A steady-state model is developed to derive these activation energies from experimental data. The newly developed coverage dependent activation energies are then implemented in the non steady-state rate-equation code MHIMS. Published experimental results on D uptake and retention of self-damaged tungsten exposed to 0.28 eV deuterium atoms at different temperatures ranging from 450 K to 1000 K can be successfully described with this approach. Finally, the steady-state model is applied to determine surface concentration, bulk concentration and migration depths of hydrogen isotopes in tungsten exposed to various atomic fluxes and temperatures ranging from milder conditions in laboratory experiments to divertor strike point conditions in tokamaks.

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Section: Discussionsupporting

confidence: 88%

Section: Surfacementioning

confidence: 56%

Section: Impact On the Calculation Of The Solution Energymentioning

confidence: 99%

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Kinetic model for hydrogen absorption in tungsten with coverage dependent surface mechanisms

Hodille¹,

Markelj²,

Pečovnik³

et al. 2020

Nucl. Fusion

Self Cite

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“…As in our previous studies of the interactions of hydrogen with tungsten surfaces 17,18 , herein we use a similar periodic plane-wave DFT model as implemented in Quantum Espresso package 19 .…”

Section: Density Functional Theory Surface Model and Numerical Parame...mentioning

confidence: 99%

“…More precisely, Bergstrom et al, 35 and Nojima et al 24 established two diffusion paths for hydrogen on the W(110) plane: one along the TF-LB-TF adsorptions sites with related activation barrier of 0.30 eV, and another one along the TF-SB-TF path with an activation barrier of 0.07 eV. In the z-direction, the activation barrier for desorption is much higher at around 0.8eV 17 . As a result, the propensity of hydrogen to move almost freely in 1D only along the TF-SB-TF path of W(110) would be established.…”

Section: -W(110) Surfacementioning

confidence: 99%

Predictive Atomistic Model for Hydrogen Adsorption on Metal Surfaces: Comparison with Low-Energy Ion Beam Analysis on Tungsten

et al. 2021

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We present an analytical thermodynamic model of a surface in contact with a gas phase which enables us to determine the surface coverage of the adsorbate depending on the temperature, pressure and chemical potential of the gas. This model is applied to both the W(110) and W(100) surface of tungsten in contact with hydrogen. The thermodynamic model is built upon data computed by density functional theory that provide the complete electronic and vibrational energetics of both surfaces. It is further compared to experimental measurements of hydrogen coverage during isobar exposure at various temperature acquired via low energy ion scattering and direct recoil spectroscopy techniques. On W(110), the agreement is quantitative provided that an additional degree of freedom is added to the model. This degree of freedom accounts for the translational motion of the adsorbate along 1D channel on the surface. On W(100), surface reconstruction makes the energetics of the system more complex; the full details of the experimental isobar are not well reproduced, although the overall consistency is obtained. We end-up with a thermodynamic model based on DFT data having accurate predictive capabilities to determine the hydrogen coverage of tungsten at any p and T.

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A review of surface damage/microstructures and their effects on hydrogen/helium retention in tungsten

Zheng

Wei

et al. 2020

Tungsten

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Surface coverage dependent mechanisms for the absorption and desorption of hydrogen from the W(1 1 0) and W(1 0 0) surfaces: a density functional theory investigation

Abstract: Surface coverage dependent mechanisms for the absorption and desorption of hydrogen from the W(110) and W(100) surfaces: a DFT investigation.

Cited by 25 publications

References 80 publications

Kinetic model for hydrogen absorption in tungsten with coverage dependent surface mechanisms

Kinetic model for hydrogen absorption in tungsten with coverage dependent surface mechanisms

Predictive Atomistic Model for Hydrogen Adsorption on Metal Surfaces: Comparison with Low-Energy Ion Beam Analysis on Tungsten

A review of surface damage/microstructures and their effects on hydrogen/helium retention in tungsten

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