Berlin 2015 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 15: Hydrogen in metals III: Experiments

MM 15.6: Vortrag

Montag, 16. März 2015, 17:30–17:45, TC 006

Hydride phase precipitation and growth in thin Nb-H films — •Vladimir Burlaka, Stefan Wagner, and Astrid Pundt — Institut für Materialphysik, Universität Göttingen, Göttingen, Germany

In thin Me-H films below the critical thickness, hydrogen absorption and hydride precipitation are expected to be controlled by mechanical stress arising because of the interface matching between the film and the substrate as well as between the hydride precipitates and the surrounding host-matrix [1,2].

In the present study we experimentally address the effect of the film thickness on hydride precipitation and growth in Nb-H thin films of 15 - 40 nm. Hydrogen gas loading is performed for in-situ Scanning Tunneling Microscopy [1] and in-situ XRD measurements to study the hydride precipitates volume content, their lateral distribution and their mean lateral sizes. We found a strong change in the lateral distribution and the mean size at the critical film thickness, for similar pressures applied. It will be demonstrated that XRD pattern generally change when the film thickness is decreased below the critical thickness, making hydrides invisible [2]. But, STM images clearly verify the presence of hydrides even in the thin thickness range.

Financial support by the DFG via PU131/9 and PU131/12, as well as by the DESY/HASYLAB and the ESRF, Grenoble, are gratefully acknowledged.

[1] K. Nörthemann and A. Pundt, Phys. Rev. B 78 (2008) 014105. [2] V. Burlaka, S.Wagner and A. Pundt. accepted for publication in JALCOM.