Regensburg 2013 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 14: Functional Materials - Hydrogen
MM 14.7: Vortrag
Montag, 11. März 2013, 17:15–17:30, H26
In-situ EELS studies on the dehydrogenation of nanocrystalline MgH2 — •Alexander Surrey1,2, Inge Lindemann1,2, Christian Bonatto Minella1, Ludwig Schultz1,2, and Bernd Rellinghaus1 — 1IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany — 2TU Dresden, Institut fur Festkörperphysik, D-01062 Dresden, Germany
In the field of hydrogen storage there is a still ongoing search for a material that provides both high H2 storage density and good H2 sorption properties. Here, nanosized or nanoconfined hydrides promise improved thermodynamics and kinetics. As for the structural characterization utilizing TEM, however, most materials degrade fast upon the irradiation with the imaging electron beam due to radiolysis. MgH2 is one of the best studied binary hydrides due to its relatively high storage capacity of 7.6 wt.% H2. Therefore, ball milled MgH2 was used as a reference material for in-situ TEM experiments on submicron particles. Hereto, EELS measurements were conducted in an aberration-corrected FEI Titan3 80-300 microscope. From an observation of the plasmonic absorptions it is found that MgH2 successively converts into Mg upon electron irradiation. The temporal evolution of the spectra is analyzed quantitatively to determine the fractions of pure and hydrogenated Mg at different stages of the reaction and to determine the critical electron doses for both incident electron energies of 80 keV and 300 keV. By comparing these critical doses the dehydrogenation kinetics of individual particles can be investigated. This understanding is also crucial for TEM studies on other hydrides such as AlH3.