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MM: Fachverband Metall- und Materialphysik

MM 15: Poster session I

MM 15.19: Poster

Montag, 7. März 2016, 18:00–20:00, Poster B3

Hydrogen sorption kinetics in magnesium and titanium hydride thin films — •Efi Hadjixenophontos, Lukas Michalek, and Guido Schmitz — University of Stuttgart, IMW, Heisenbergstrasse 3, 70569 Stuttgart Germany

Magnesium hydride is a model material which is intensively studied for hydrogen sorption in the last few years. Beside its favorable abundance, it is known for its high weight capacity of about 7 wt.% of hydrogen (H). It's a reversible storage system. However, it suffers from slow kinetics which makes it operational at only high temperatures. Research has shown that transition metals (TM) can improve this properties. In this work, we focus on the H-sorption behavior in thin films of thicknesses between 50-400nm in different conditions. The focus is to compare the kinetic properties and diffusion coefficients between TiH2 and MgH2 and multilayers thereof. Mg requires a thin Palladium (Pd) film on top for the hydrogenation to take place. Pure Mg/Pd and Ti metals were deposited by ion beam sputtering on Si/SiO2 substrates. Hydrogenation of these layers followed at different temperatures (RT-300°C) and for different duration of times (10-600min) at 1-20 bars of H atmosphere. Full dehydrogenation of the samples has been tested and is shown to be more challenging for the TiH2 because of its stability. Microstructure was studied by TEM. SEM was used for surface analysis. XRD is applied to quantify the hydrogen-sorption process and diffusion coefficients. Quantitative measurements and evaluation at different temperatures will be presented that allow determination of diffusivity and surface reaction coefficients.