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Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 49: Hydrogen in Metals

MM 49.5: Vortrag

Freitag, 27. März 2009, 11:15–11:30, IFW D

Atom probe tomography analyses of deuterium distribution in Fe/V multi-layered films — •Ryota Gemma, Talaat Al-Kassab, Reiner Kirchheim, and Astrid Pundt — Institut fuer Materialphysik, Friedrich-Hund-Platz 1, D-37077, Goettingen, Germany

Recently, the interaction of hydrogen with metallic multi-layered thin films remains as a hot topic. A detailed knowledge on such chemically modulated systems is required if they are desired for application in hydrogen energy system as storage media. In this study, the deuterium (D) concentration profile of Fe/V multi-layer was investigated by atom probe tomography (APT) between 60 and 20 K. It is firstly shown that a deuterium-loaded sample can easily react with oxygen at Pd capping layer on Fe/V and therefore, it is required to avoid any oxygen exposure after D2 loading before APT analysis. The analysis temperature also has an impact on the D concentration profile. The results taken at 60 K show clear traces of surface segregation of D atoms diffusing towards the analysis surface. The observed diffusion profile of D regarding analysis time allows us to estimate an apparent diffusion coefficient. The calculated diffusion coefficient at 60 K is in the order of 10−17cm2/s which deviates about 6 orders of magnitude from a value extrapolated from high temperatures. Below 30 K, the D concentration profile shows no segregation anymore and a homogeneous distribution with cD = 0.05(2) D/Me, which is in good accordance with that measured in corresponding pressure-composition isotherm of H-Fe/V system.

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