Dresden 2014 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 60: Nanomaterials IV - Deformation and mechanical properties

MM 60.4: Vortrag

Donnerstag, 3. April 2014, 16:30–16:45, IFW B

Ultra high stresses in thin Nb-H films — •Magnus Hamm, Vladimir Burlaka, Stefan Wagner, and Astrid Pundt — Universität Göttingen, Institut für Materialphysik, Friedrich-Hund-Platz 1, 37077 Göttingen

Mechanical stress influences different material properties. Some examples are the change of the critical temperature [1], the change of the electromotoric force [2] or changes in the energy-band structure [3].For thin metal films clamped to a rigid substrate, hydrogen absorption on interstitial lattice sites results in compressive mechanical stress. Up to -3.4 GPa have been measured by Laudahn et al. for Nb-films.[4] While for low concentrations the stress increases linearly with the hydrogen content, the stress increase is reduced by the creation of dislocations, for higher concentrations. As suggested by Nörthemann et al.[5] the mechanical stress evolution depends on the film thickness: Below a critical thickness of the film the formation of dislocations even becomes energetically unfavorable. It is shown that below this critical thickness the stress increases to very high values. This observed stress change is reversible.

Financial support by the DFG via project PU131/12-1 is gratefully acknowledged.

[1] J. Weissmuller and C. Lemier, Philos. Mag. Lett. 80:6 (2000)

[2] R. Kirchheim, Acta metall. 1:34 (1986)

[3] R. People, IEEE J. Quantum Electron., 22:6 (1986)

[4] U. Laudahn et al., J. Alloys Compd. 293-295:20 (1999)

[5]K. Nörthemann and A. Pundt, Phys. Rev. B 78:1 (2008)