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Hydrogen as a probe for defects in materials: Isotherms and related microstructures of palladium-hydrogen thin films

Wagner, Stefan; Pundt, Astrid

Abstract:

Metal-hydrogen systems offer grand opportunities for studies on fundamental aspects of alloy thermodynamics. Palladium-hydrogen (Pd-H) thin films of nano crystalline, multi-oriented and epitaxial microstructures, electrolytically charged with hydrogen, serve as model systems. In these films thermodynamics of hydrogen absorption is modified by interface effects related to mechanical stress and to microstructural defects. Since in this respect hydrogen can be utilized to reveal the microstructural constituents of the films, we aim to investigate the distribution of sites (DOS) hydrogen occupies in the films’ solid solution regime. A σDOS model is proposed, taking the measured substrate-induced stress contribution to the chemical potential into account. This enables the determination of the different sites’ volume fractions and of pure site energy distributions by fitting measured isotherms. Interstitial sites, grain/domain boundary sites and deep traps are distinguished. Dislocations and vacancies are shown to have a minor impact on the films’ trapping of hydrogen atoms, while deep traps are related to the films’ surface. Enhanced binding energies in nano crystalline films can be ascribed to the tensile strain effect of grain boundaries acting on the grains. ... mehr


Verlagsausgabe §
DOI: 10.5445/IR/1000121373
Veröffentlicht am 28.11.2021
Originalveröffentlichung
DOI: 10.3934/matersci.2020.4.399
Dimensions
Zitationen: 2
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Materialien – Werkstoffkunde (IAM-WK)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 2372-0484
KITopen-ID: 1000121373
Erschienen in AIMS Materials Science
Verlag AIMS Press
Band 7
Heft 4
Seiten 399–419
Nachgewiesen in Dimensions
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