Dresden 2003 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 24: Poster

DS 24.50: Poster

Dienstag, 25. März 2003, 14:30–17:00, P2a

IN-SITU STUDIES OF GASOCHROMIC SWITCHING — •Christian Salinga, Pascal Meyers, Christoph Liesch, Theofilos Eleftheriadis, Hansjörg Weis, Tom P. L. Pedersen, and Matthias Wuttig — I. Physikalisches Institut A, RWTH Aachen, D-52056 Aachen

Optical spectroscopy, spectroscopic ellipsometry and stress measurements are employed to study the kinetics and mechanism of gasochromic switching upon hydrogen exposure of several thin films systems including Pd, Mg, Gd and WO₃. Stress measurements reveal that the smallest stresses of around 250 MPa are built up for WO₃, where gasochromic switching is completely reversible. Stresses which are larger by up to 2 orders of magnitude are observed for Pd, Mg and Gd films. These other materials shown evidence for irreversible deformation upon hydrogen loading and at least for Mg also a rapid property degradation upon repeated switching.

The kinetics of the switching process have also been studied by fast, time resolved measurements using optical spectroscopy and spectroscopic ellipsometry. Together with the stress measurements these data enable us to identify the atomic mechanism of hydrogen induced switching. Interesting enough these measurements reveal that the film thickness only shows marginal changes upon hydrogen exposure. This finding is in line with recent x-ray reflectometry measurements.