Berlin 2015 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 2: Thin Film Characterisation I: Structure Analysis and Composition

DS 2.11: Vortrag

Montag, 16. März 2015, 12:15–12:30, H 0111

In situ X- Rays measurements of lattice expansion on metallic superlattices. — •Sotirios A. Droulias, Lennard Mooij, Gunnar K. Palsson, Xin Xiao, Vassilios Kapaklis, Bjorgvin Hjorvarson, and Max Wolff — Materials Physics, Division of Physics and Astronomy, Uppsala University, Sweden

Transition metals are exceptional candidates for hydrogen storage applications since large H quantities can be effectively absorbed. By growing superlattices of such materials, finite size and proximity effects can be investigated. In our work, we present expansion measurements of Cr-V and Fe-V superlattices by using in situ X-Ray diffraction. From the expansion measurements the elastic constants of the material can be extracted and related to the hydrogen interaction which is mediated by elastic forces. A complete and accurate description of the host lattice under various H pressures (concentrations) and different temperatures provide us with a unique tool for understanding the system*s thermodynamics. From the volume expansion one can derive the site occupancy of H in the host material and if combined with other techniques, such as optical transmition, and curvature measurements a complete image of the system can be drawn. The different techniques can be correlated directly through resistivity measurements. This forms the basis for understanding the observed phase transitions in such systems and the influence of finite size and proximity. Furthermore, characterization of the host lattice under various conditions is a detailed quality description after repeated loading and unloading of the hydrogen containing material.