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MM: Fachverband Metall- und Materialphysik
MM 20: Topical session (Symposium MM): Hydrogen in Materials
MM 20.2: Vortrag
Dienstag, 13. März 2018, 10:45–11:00, H 0107
Thermodynamic and elastic properties of palladium-hydrides from first principles — •Beatrix Elsner, Gregor Feldbauer, and Stefan Müller — Hamburg University of Technology, Institute of Advanced Ceramics, Denickestr. 15, D-21073 HH
Palladium and Pd-based alloys exhibit a huge potential for widespread applications ranging from hydrogen storage to catalytic processes. Because of its ability to reversibly embed a significant amount of hydrogen into interstitial sites, palladium is often characterized as a "hydrogen sponge". With increasing amount of absorbed hydrogen, the mechanical properties of palladium-hydride (PdHx) are affected, e.g. it becomes more susceptible to brittle fracture. In order to understand such phenomena in more detail, the thermodynamic stability and elastic properties of PdHx are here investigated via ab initio methods. Dispersion-corrected density functional theory (DFT) calculations are performed to obtain the energetics as well as the elastic properties of PdHx for hydrogen concentrations up to 100%. The significant effect of phonon contributions is considered within the harmonic approximation. Using the DFT results as input data, cluster-expansion Hamiltonians for the phase formation energy as well as for the elastic properites are constructed to scan exhaustively the entire configuration space of PdHx. This approach allows us to identify the most favorable configurations (ground states) as well as to identify trends for the elastic properties, such as a decrease of the shear constant c44 with increasing hydrogen concentration.