Pundt, Astrid

[["dc.bibliographiccitation.firstpage","99"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Procedia Engineering"],["dc.bibliographiccitation.lastpage","103"],["dc.bibliographiccitation.volume","1"],["dc.contributor.author","Cizek, J."],["dc.contributor.author","Prochazka, I."],["dc.contributor.author","Vlach, M."],["dc.contributor.author","Zaludova, N."],["dc.contributor.author","Dobron, P."],["dc.contributor.author","Chmelik, F."],["dc.contributor.author","Brauer, G."],["dc.contributor.author","Anwand, W."],["dc.contributor.author","Mücklich, A."],["dc.contributor.author","Nikitin, E."],["dc.contributor.author","Gemma, R."],["dc.contributor.author","Pundt, A."],["dc.contributor.author","Kirchheim, R."],["dc.date.accessioned","2019-07-09T11:40:46Z"],["dc.date.available","2019-07-09T11:40:46Z"],["dc.date.issued","2009"],["dc.description.abstract","Hydrogen loading causes a significant volume expansion, which is isotropic in free-standing bulk materials. Contrary to bulk samples, thin films are clamped to an elastically stiff substrate, which prevents in-plane expansion. Hence, volume expansion of a thin film is strongly anisotropic because it expands only in the out-of-plane direction. High internal stresses introduced during hydrogen loading may lead to a situation when detachment of film from the substrate is energetically favorable. In the present work, we studied hydrogen-induced buckling of thin Pd films using a multi-scale approach. Defects in buckled films were characterized on the atomic level by positron annihilation spectroscopy combined with microstructure studies by transmission electron microscopy. Meso-scale measurements were performed by acoustics emission. Observations at the macroscopic level were performed by optical microscopy. It was found that buckling of thin films occurs at hydrogen concentrations xH>0.1. Defect studies of buckled Pd films revealed a significant increase of dislocation density in agreement with acoustic emission studies which demonstrated a correlated movement of dislocations with a well-defined threshold coinciding with the onset of buckling."],["dc.identifier.doi","10.1016/j.proeng.2009.06.024"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/11293"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/58244"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1877-7058"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","CC BY-NC-ND 3.0"],["dc.rights.uri","http://creativecommons.org/licenses/by-nc-nd/3.0/"],["dc.title","Multi-scale analysis of hydrogen-induced buckling in Pd films"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","9564"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Scientific reports"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Burlaka, Vladimir"],["dc.contributor.author","Roddatis, Vladimir"],["dc.contributor.author","Bongers, Marian David"],["dc.contributor.author","Pundt, Astrid"],["dc.date.accessioned","2019-07-09T11:43:39Z"],["dc.date.available","2019-07-09T11:43:39Z"],["dc.date.issued","2017-08-25"],["dc.description.abstract","In this paper, we demonstrate that the microstructure and the surface of a thin palladium (Pd) film can be intentionally altered by the presence of a subjacent niobium (Nb) film. Depending on the thickness of the Nb film and on the hydrogen gas pressure, defects in the Pd film can be healed or created. To demonstrate this effect, Pd/Nb/sapphire (Al2O3) stacks are studied during hydrogen gas exposure at room temperature by using scanning tunneling microscopy (STM), X-ray diffraction (XRD) and environmental transmission electron microscopy (ETEM). STM shows that hydrogen-induced topography changes in the Nb films depend on the film thickness which affects the height of the Nb surface corrugations, their lateral size and distribution. XRD measurements show that these changes in the Nb hydride film influence the microstructure of the overlaying Pd film. ETEM reveals that the modifications of the Pd film occur due to the precipitation and growth of the Nb hydride phase. The appearance of new defects, interface and surface roughening is observed in the Pd film above locally grown Nb hydride grains. These results can open a new route to design 'smart' catalysts or membranes, which may accommodate their microstructure depending on the gaseous environment."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2017"],["dc.identifier.doi","10.1038/s41598-017-09900-z"],["dc.identifier.pmid","28842694"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/14614"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/58939"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","2045-2322"],["dc.relation.orgunit","Fakultät für Physik"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.rights","CC BY 4.0"],["dc.subject.ddc","530"],["dc.title","Defect generation in Pd layers by 'smart' films with high H-affinity."],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","7848"],["dc.bibliographiccitation.issue","22"],["dc.bibliographiccitation.journal","Molecules"],["dc.bibliographiccitation.volume","27"],["dc.contributor.affiliation","Gemma, Ryota; 1Department of Applied Chemistry, Tokai University, Hiratsuka 259-1292, Japan"],["dc.contributor.affiliation","Al-Kassab, Talaat; 3Institute of Materials Physics, University of Göttingen, 37077 Göttingen, Germany"],["dc.contributor.affiliation","Pundt, Astrid; 3Institute of Materials Physics, University of Göttingen, 37077 Göttingen, Germany"],["dc.contributor.author","Gemma, Ryota"],["dc.contributor.author","Al-Kassab, Talaat"],["dc.contributor.author","Pundt, Astrid"],["dc.date.accessioned","2022-12-07T15:55:21Z"],["dc.date.available","2022-12-07T15:55:21Z"],["dc.date.issued","2022-11-14"],["dc.date.updated","2022-12-07T14:46:35Z"],["dc.description.abstract","The recent progress of Atom Probe Tomography (APT) has opened up atomic-scale elemental analysis including hydrogen species. For APT measurements, the use of deuterium is highly recommended, due to its low mobility compared to the fast and quantum mechanically tunneling isotope hydrogen. In addition, deuterium can be distinguished from hydrogen originating from the APT analysis chamber. To date, however, APT studies on materials with high D concentrations are scarce. In this study, the D concentration profile in a Fe/V multi-layered film sample was investigated, and spanned a wide concentration range. The mean hydrogen isotope concentration was alternatively quantified by electromotive force (EMF) measurements on a similar Fe/V film, thus verifying the APT results. The reduction found in the D concentration at the Fe/V interface results from local alloying at the Fe/V interfaces which accompanies a change in the available volume in the V lattice. Even at the same Fe concentration, the shape of the observed D depth profile was asymmetric at high D2 pressures. This indicates a stress impact caused by the deposition sequence."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG)"],["dc.identifier.doi","10.3390/molecules27227848"],["dc.identifier.pii","molecules27227848"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/118488"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-621"],["dc.relation.eissn","1420-3049"],["dc.rights","CC BY 4.0"],["dc.title","Deuterium Distribution in Fe/V Multi-Layered Films"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.contributor.author","Pundt, Astrid"],["dc.date.accessioned","2018-05-03T10:43:00Z"],["dc.date.available","2018-05-03T10:43:00Z"],["dc.date.issued","2005"],["dc.description.abstract","Was passiert mit einem Metall, wenn es in seiner Größe reduziert wird? Welche Änderungen sind zu erwarten, was ist zu berücksichtigen? Am Beispiel der Metall-Wasserstoff-Systeme (M-H-Systeme) werden hier Antworten zu diesen Fragen gegeben. Verschiedene materialphysikalische Experimente zu dünnen Schichten, Vielfachschichten und Clustern von wenigen Nanometern Größe werden vorgestellt. Die Ergebnisse werden im Hinblick auf mechanische Spannungen und Mikrostruktur (inklusive der Oberflächen) der jeweiligen Probe diskutiert. Der wichtige Einfluss des Stabilisators auf die physikalischen Eigenschaften des nanoskaligen Systems wird belegt, indem zunächst gezeigt wird, dass die nach der linearen Elastizitätstheorie zu erwartenden mechanischen Spannungen (einige GPa!) und Dehnungen in nanoskaligen M-H-Systemen tatsächlich auftreten. Viele Systeme können diesen jedoch durch Versetzungsbildung oder Ablösung vom Stabilisator ausweichen. Der Beitrag der Mikrostruktur (Korngrenzen, Versetzungen, Oberflächen, innere Grenzflächen) auf experimentell ermittelte Phasengrenzen wird abgeschätzt und es wird nachgewiesen, dass dieser Beitrag nicht zur Erklärung der experimentellen Daten genügt. Im Falle kleinster Cluster müssen neue Strukturen berücksichtigt werden, die die Phasendiagramme dieser M-H-Systeme deutlich verändern. Im Hinblick auf die zwei materialphysikalischen Schwerpunkte (Mikrostruktur und mechanische Spannungen) werden auch ältere Daten neu diskutiert, wobei für scheinbare Konflikte Lösungen angeboten werden. Das Buch gibt daher einen breiten Einblick in mögliche Veränderungen materialphyiskalischer Eigenschaften von M-H-Systemen durch die Nanoskalierung."],["dc.format.extent","155"],["dc.identifier.doi","10.17875/gup2005-71"],["dc.identifier.isbn","3-938616-11-3"],["dc.identifier.isbn","978-3-938616-11-6"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?goescholar/3232"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?isbn-3-938616-11-3"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/14049"],["dc.identifier.urn","urn:nbn:de:gbv:7-isbn-3-938616-11-3-9"],["dc.language.iso","de"],["dc.notes.intern","TASK GROB-550"],["dc.notes.status","zu prüfen"],["dc.publisher","Universitätsverlag Göttingen"],["dc.publisher.place","Göttingen"],["dc.rights.uri","http://creativecommons.org/licenses/by-nd/3.0/de"],["dc.title","Nanoskalige Metall- Wasserstoff- Systeme"],["dc.type","book"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]