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MM: Fachverband Metall- und Materialphysik
MM 27: Poster Session I
MM 27.9: Poster
Dienstag, 13. März 2018, 18:30–19:45, Poster E
HYDROGEN SORPTION KINETICS IN MgH2 AND TiH2 THIN FILMS — •Efi Hadjixenophontos1, Lukas Michalek1, Andreas Weigel1, Michael Hirscher2, and Guido Schmitz1 — 1Institut für Materialwissenschaft, (IMW) University of Stuttgart, Stuttgart, GERMANY — 2Max Planck Institute for Intelligent Systems, Stuttgart, Germany, Stuttgart, Germany
Among metal hydride materials, Mg and its alloys show a great performance for the H-fuel based economy, however they still lack of performance. Transition metals eg.Ti seem to improve such systems.Here, we study separately the 2 systems:Ti-TiH2 and Mg-MgH2 in thin films (50-800nm) which enable us to monitor the hydride growth and determine the diff.coeff.The two metals show a different hydrogenation behaviour.The linear growth, due to the oxide passivation layer, in Ti, and the H diff. coeff. inside the oxide are quantified, as well as a reliable lower bound to the H diffusion coeff. in Ti is derived.The pressure dependence of H absorption is also quantitatively modelled.Micrographs support the fast diffusivity of H into Ti known from literature, since TiH2 is first formed closer to the substrate.In Mg, micrographs show MgH2 formed underneath the surface and a layer-like growth towards the substrate is observed.Surprisingly, a transition between linear (200°C) and parabolic growth regime (300°C) is observed.Resistivity measurements at the same conditions, are investigated to support this transition.Diff. coeff. and surface transport coeff. are determined by XRD,FIB and TEM.