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MM: Fachverband Metall- und Materialphysik

MM 20: Poster session II

MM 20.14: Poster

Dienstag, 2. April 2019, 18:30–20:00, Poster C

Structural phase transitions in palladium hydrogen thin films: Mechanical stress impact on critical temperatures — •Stefan Wagner and Astrid Pundt — Karlsruhe Institute of Technology, Institute of Applied Materials (IAM-WK), Karlsruhe, Germany

Palladium hydrogen (PdH) thin films serve as model systems to study structural phase transitions under elastic and microstructural confinements. Mechanical stresses linked to hydrogen-absorption of thin films clamped onto hard substrates are used to tune the hydrogens chemical potential, changing the stability of the hydride phase. Stresses are superimposed by microstructural constraints, channelling stress relaxation processes in the films. In-situ measurements of chemical potential and mechanical stress enable the determination of the attractive H-H interaction energy and of the critical temperature of hydride formation. Thereby partially relaxed stresses yield sloped plateaus in the two-phase-coexistence region, that need to be considered in the systems thermodynamic description [1]. [1] S. Wagner, A. Pundt, Int. J. Hydr. Energy 41 (2016) 2727.