SKM 2023 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 27: Hydrogen in Materials

MM 27.5: Talk

Wednesday, March 29, 2023, 11:15–11:30, SCH A 215

Influence of impurity atoms on the hydrogen diffusion into ruthenium — •Julian Gebhardt and Daniel Urban — Fraunhofer IWM, 79108 Freiburg

Ruthenium is considered as a promising protection layer to prevent the penetration of small atoms such as hydrogen into the underlying material. However, hydrogen is known to be able to penetrate ruthenium films under certain conditions and it has been hypothesized that impurity atoms, such as Sn, could play a major role in this process, decreasing the barrier of diffusion into the material for incoming hydrogen. We demonstrate that this is not the case for low to medium coverages, i.e., as long as the adsorbed species can be treated individually without significant adsorbate-adsorbate interactions. Within this coverage regime, the hydrogenation is destabilized in the vicinity of impurity atoms, such as X=Mg, P, S, Si, or Zn, due to the strong bonding of the adsorbates with the free ruthenium surface. As a result, the diffusion barriers are not significantly reduced in the vicinity of any of the tested impurity atoms. The most likely and energetically favorable process occurs at a sufficiently large distance to the impurity, with an energy barrier that is almost identical to that of the free surface. Due to the chemical variety of the considered impurity atoms, this finding appears to be general. This means that impurities can be ruled out to enhance hydrogen uptake of ruthenium layers for the considered coverages and other structural properties such as grain boundaries and dislocations should be considered as pathway for the hydrogen penetration.