Dresden 2017 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 34: Poster session II
MM 34.34: Poster
Dienstag, 21. März 2017, 18:30–20:30, P4
Imaging and kinetics of MgH2 and TiH2 formation — •Efi Hadjixenophontos1, Lukas Michalek1, Manuel Roussel1, Andreas Weigel1, Toyoto Sato2, Shin-ichi Orimo2,3, and Guido Schmitz1 — 1Institut für Materialwissenschaft, (IMW) University of Stuttgart, Heisenbergastrasse 3, 70569 Stuttgart, GERMANY — 2Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 JAPAN — 3WPI-Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 JAPAN
Among the metal hydrides, Mg and its alloys show an excellent performance for the H-fuel based economy.In order to improve the system, it is first important,to understand the reason for the slow kinetics of hydride formation, which is surprisingly still an open field of research and the focus of this work. TM-metals,have shown to lower the activation energy, and therefore improve the kinetics.Here we study separately the two systems: MgH2 with Pd as catalyst, and TiH2 thin films and compare them to their bulk behaviour.The two metals show a different mechanism of hydrogenation, and the oxide layer in the case of Ti seems to have a great impact. Hydrogen diffuses in Ti faster and TiH2 is first formed closer to the substrate.In the case of Mg a microscopic imaging of the co-existence of the hydride and pure phases shows that MgH2 is immediately formed at the interface between the Pd catalyst coating and the Mg thin film and it grows in a layer-like reaction towards the substrate.XRD,SEM-FIB and TEM are the combined techniques used to discus the diffusion coefficients and mechanisms of hydrogenation.