Quasi-thermodynamic model on hydride formation in palladium-hydrogen thin films: Impact of elastic and microstructural constraints
2016 | journal article; research paper. A publication with affiliation to the University of Göttingen.
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Quasi-thermodynamic model on hydride formation in palladium-hydrogen thin films: Impact of elastic and microstructural constraints
Wagner, S. & Pundt, A. (2016)
International Journal of Hydrogen Energy, 41(4) pp. 2727-2738. DOI: https://doi.org/10.1016/j.ijhydene.2015.11.063
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- Authors
- Wagner, Stefan ; Pundt, Astrid
- Abstract
- The impact of elastic and microstructural constraints on structural phase transitions is investigated by using (10-300) nm Pd-H films of different microstructures. Hydrogen induced stress mainly arises from the film's adhesion to a substrate. Stress changes the hydrogens' chemical potential mu(H), modifying the hydride phase stability. Microstructural constraints channel stress release in films. A thermodynamic model is proposed to deduce the H-H interaction energy E-HH and an effective critical temperature T-c(eff) of hydride formation in films. It allows for occasionally observed sloped plateaus of mu(H) below T-c(eff). EHH (between 15 and 30 kJ/mol(H)) and T-c(eff) (340 K to 490 K) are reduced by up to 50% compared to bulk (E-HH = 36.8 kJ/mol(H), T-c = 563 K), for all films. Concentration-dependent contributions of substrate-induced stress (of about (2-5) kJ/mol(H)) and microstructure (of about (5-8) kJ/mol(H)) are separated. For all films phase separation is still found at 300 K. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
- Issue Date
- 2016
- Journal
- International Journal of Hydrogen Energy
- Organization
- Institut für Materialphysik
- ISSN
- 1879-3487; 0360-3199
- Sponsor
- Deutsche Forschungsgemeinschaft [PU 131/7-2, PU 131/9-1]