Regensburg 2007 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 17: Hydrogen in materials
MM 17.2: Vortrag
Dienstag, 27. März 2007, 10:30–10:45, H6
The effect of the structure and the stabilizer on the hydrogen absorption in palladium clusters — •M. Suleiman1, D. Fritsch2, C. Borchers1, R. Kirchheim1, and A. Pundt1 — 11Instiute of Material physics, University of Goettingen Friedrich-Hund-Platz 1, 37077 Goettingen, Germany. — 2GKSS Research Centre Geesthacht GmbH, Institute of Polymer Research, Max-Planck-Str. 1, 21502 Geesthacht, Germany
In this work the hydrogen absorption behaviour of two types of Pd-clusters, different in structure, will be presented: First, icosahedral Pd clusters stabilized in tetraoctylammonium bromide (TOAB). Second, cubic Pd clusters (Pd-Teflon AF) stabilized in Teflon AF matrix. The phase transition in these samples was monitored by in situ X-ray diffraction. It is shown that the hydrogen uptake ability depends strongly on the lattice structure which is affected by the type of stabilizer. Teflon AF stabilized clusters show the phase transition which is common for bulk, whereas TOAB stabilized clusters show only weak lattice dilatation upon hydrogen absorption. P-c Isotherms show that the Teflon AF stabilized clusters (the cubic clusters) absorb large amounts of hydrogen both in comparison to bulk Pd and to the TOAB stabilized icosahedral clusters. The measured solubility is higher than that for TOAB-clusters, and even higher than that expected for bulk palladium.. This suggests that surface sites are available for hydrogen in the Pd-Teflon-AF samples which are not accessible for Pd-TOAB-clusters, and that the icosahedral lattice absorbs less hydrogen for similar external pressures.