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MM: Fachverband Metall- und Materialphysik
MM 33: Topical Session: Interface-dominated phenomena - Hydrogen at Interfaces
MM 33.4: Vortrag
Mittwoch, 18. März 2020, 11:00–11:15, IFW A
Niobium Hydrogen Thin Films: Mechanical Stress, Interface Coherency and Phase Equilibria — •Stefan Wagner1, Philipp Klose1, Vladimir Burlaka2, Kai Nörthemann2, Magnus Hamm2, and Astrid Pundt1 — 1Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany — 2Göttingen University, Institute of Applied Materials, Göttingen, Germany
Metal-hydrogen systems offer grand opportunities for studies on fundamental aspects of alloy thermodynamics and kinetics. When the system size is reduced to the nanoscale, interface effects related to microstructural defects as well as mechanical stress affect the systems' properties [1]. In thin films the lattice expansion linked to hydrogen absorption is hindered by the substrate. Resulting stresses are usually compensated by plastic deformation, lowering the film's coherency state. Here we show for the model case of niobium-hydrogen (Nb-H) thin films on sapphire substrates that plastic deformation is suppressed below critical values of film thickness. This yields ultra-high stresses of up to -10 GPa, changing the film's phase stabilities, phase diagrams as well as the phases' nucleation and growth dynamics. [1] S. Wagner et al., Chem. Phys. Chem. 20 (2019) 1890.