Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 41: Poster SYM Hydrogen in Materials: New Developments

MM 41.7: Poster

Thursday, February 28, 2008, 18:00–20:00, Poster B

Mechanical stress impact on thin films thermodynamic properties - investigated by H-loading — •Stefan Wagner and Astrid Pundt — Institut für Materialphysik der Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen

Thermodynamic properties of thin films deviate strongly from those of bulk. The deviations are reported to originate from microstructure and from mechanical stress, while the contribution of both is unknown in particular. Focussing on the mechanical stress contribution and by using Pd-H and PdFe-H as model systems, it is shown that mechanical stress strongly changes phase transition pressures. For the Pd-H films the measured loading pressures shift up to 140 mbar in contrast to 18 mbar for bulk. These shifts relate to the film bonding to the substrate and can be affected by film detachment.