Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-25976 Zeitschriftenartikel Grothausmann, R.; Zehl, G.; Manke, I.; Fiechter, S.; Bogdanoff, P.; Dorbandt, I.; Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Schumacher, G.; Banhart, J. Dreidimensionale Charakterisierung von Katalysatornanopartikeln We present transmission electron microscope (TEM) tomography investigations of ruthenium-based fuel cell catalyst materials as employed in direct methanol fuel cells (DMFC). The digital three-dimensional representation of the samples not only enables detailed studies on number, size, and shape but also on the local orientation of the ruthenium particles to their support and their freely accessible surface area. The shape analysis shows the ruthenium particles deviate significantly from spherical symmetry which increases their surface to volume ratio. The morphological studies help to understand the structure formation mechanisms during the fabrication as well as the high effectiveness of these catalysts in the oxygen reduction reaction at the cathode side of fuel cells. München Carl Hanser Deutsche Gesellschaft für Materialkunde 2012 International journal of materials research 103 1 135 136 2016-02-19 OPUS4-26348 Zeitschriftenartikel Grothausmann, R.; Zehl, G.; Manke, I.; Fiechter, S.; Bogdanoff, P.; Dorbandt, I.; Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Schumacher, G.; Banhart, J. Nanometer-Tomographie: kleinste Katalysatorteilchen erblicken - Mit Elektronen und Computern die mobile Brennstoffzelle erforschen Weinheim Wiley-VCH Verl. Gesellschaft für Korrosionsschutz 2012 Materials and corrosion 63 2 1 10.1002/maco.201290007 2016-02-19 OPUS4-24833 Zeitschriftenartikel Grothausmann, R.; Zehl, G.; Manke, I.; Fiechter, S.; Bogdanoff, P.; Dorbandt, I.; Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Schumacher, G.; Banhart, J. Quantitative structural assessment of heterogeneous catalysts by electron tomography We present transmission electron microscope (TEM) tomography investigations of ruthenium-based fuel cell catalyst materials as employed in direct methanol fuel cells (DMFC). The digital three-dimensional representation of the samples not only enables detailed studies on number, size, and shape but also on the local orientation of the ruthenium particles to their support and their freely accessible surface area. The shape analysis shows the ruthenium particles deviate significantly from spherical symmetry which increases their surface to volume ratio. The morphological studies help to understand the structure formation mechanisms during the fabrication as well as the high effectiveness of these catalysts in the oxygen reduction reaction at the cathode side of fuel cells. Washington, DC American Chemical Society 2011 Journal of the American chemical society 133 45 18161 18171 10.1021/ja2032508 2016-02-19 OPUS4-22072 Zeitschriftenartikel Grothausmann, R.; Manke, I.; Zehl, G.; Dorbandt, I.; Bogdanoff, P.; Fiechter, S.; Hentschel, Manfred P.; Lange, Axel; Kupsch, Andreas; Hilger, A. Charakterisierung von Katalysatormaterialien für Brennstoffzellen mittels Elektronentomografie Zur Optimierung moderner Katalysatoren für Brennstoffzellen werden diese elektronen-tomografisch charakterisiert. Die Elektronentomografie ermöglicht einzigartige Einblicke in die Nanometer-Strukturen der metallischen Katalysatorpartikel, die auf einem elektrisch leitenden, inerten Kohlenstoffträger abgeschieden werden. Die dreidimensional bildgebende Methode ermöglicht über qualitative Untersuchungen hinaus detaillierte quantitative Form- und Strukturanalysen der Katalysatormaterialien. So werden beispielsweise die Positionen der Katalysatorpartikel relativ zum Trägermaterial analysiert. Ihre Form und Einbettung in den Träger, welche die für die katalytische Reaktion maßgebliche "freie Oberfläche" definieren, werden bestimmt. Die Elektronentomografie ermöglicht somit quantitative Vergleiche zwischen verschiedenen Katalysatormaterialien und Herstellungsverfahren. Sie erweitert die Möglichkeiten der Korrelation gewünschter elektrochemischer Eigenschaften mit der Nanostruktur dieser Materialien und macht so weitere Optimierungen der Katalysatormaterialien möglich. München Hanser Bundesanstalt für Materialforschung und -prüfung 2010 MP materials testing 52 10 706 711 2016-02-19 OPUS4-59666 Zeitschriftenartikel Trogadas, P.; Cho, J. I. S.; Rasha, L.; Lu, X.; Kardjilov, N.; Markötter, Henning; Manke, I.; Shearing, P. R.; Brett, D. J. L.; Coppens, M. O. A nature-inspired solution for water management in flow fields for electrochemical devices A systematic, nature-inspired chemical engineering approach is employed to solve the issue of flooding in electrochemical devices. The mechanism of passive water transport utilized by lizards living in arid environments is leveraged to design flow-fields with a microchannel structure on their surface, through which capillary pressure rapidly removes the water generated in the electrochemical device. This water management strategy is implemented in proton exchange membrane fuel cells (PEMFCs) with a lunginspired flow-field, which ensures uniform distribution of reactants across the catalyst layer. Jointly, this nature-inspired approach results in flood-free, stable operation at 100% RH and a B60% increase in current (B1.9 A cm-2) and peak power density (B650 mW cm−2) compared to current PEMFCs with a flood-prone, serpentine flow-field (B0.8 A cm-2 and 280 mW cm-2, respectively). This significant advance allows for PEMFC operation at fully humidified conditions. Royal Society of Chemistry (RSC) 2024 Energy & Environmental Science 17 2007 2017 urn:nbn:de:kobv:b43-596662 10.1039/d3ee03666a https://creativecommons.org/licenses/by/4.0/deed.de 2024-03-18 OPUS4-53842 Zeitschriftenartikel Wu, Y.; Lu, X.; Cho, J.I.S.; Rasha, L.; Whiteley, M.; Neville, T. P.; Ziesche, R.; Kardjilov, N.; Markötter, Henning; Manke, I.; Zhang, X.; Shearing, P. R.; Brett, D. J. L. Multi-length scale characterization of compression on metal foam flow-field based fuel cells using X-ray computed tomography and neutron radiography The mechanical compression of metal foam flow-field based polymer electrolyte fuel cells (PEFCs) is critical in determining the interfacial contact resistance with gas diffusion layers (GDLs), reactant flow and water management. The distinct scale between the pore structure of metal foams and the entire flow-field warrant a multilength scale characterization that combines ex-situ tests of compressed metal foam samples and in-operando analysis of operating PEFCs using X-ray computed tomography (CT) and neutron radiography. An optimal 'medium' compression was found to deliver a peak power density of 853 mW/cm². The X-ray CT data indicates that the compression process significantly decreases the mean pore size and narrows the pore size distribution of metal foams. Simulation results suggest compressing metal foam increases the pressure drop and gas velocity, improving the convective liquid water removal. This is in agreement with the neutron imaging results that demonstrates an increase in the mass of accumulated liquid water with minimum compression compared to the medium and maximum compression cases. The results show that a balance between Ohmic resistance, water removal capacity and parasitic power is imperative for the optimal performance of metal foam based PEFCs. Elsevier Ltd. 2021 Energy Conversion and Management 239 10 113785 10.1016/j.enconman.2020.113785 2021-11-29 OPUS4-7383 misc Treimer, W.; Feye–Treimer, U.; Radke, C.; Hilger, A.; Neumann, O.; Manke, I.; Haibel, A.; Rack, A.; Riesemeier, Heinrich Investigations of mamma biopsies by means of µ-tomography Berlin Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung 2005 BESSY highlights - annual report 2004 452 453 2016-02-19 OPUS4-26317 Zeitschriftenartikel Markötter, H.; Manke, I.; Kuhn, R.; Arlt, Tobias; Kardjilov, N.; Hentschel, Manfred P.; Kupsch, Andreas; Lange, Axel; Hartnig, C.; Scholta, J.; Banhart, J. Neutron tomographic investigations of water distributions in polymer electrolyte membrane fuel cell stacks Neutron tomography was applied to study the 3D water distribution in full polymer electrolyte membrane fuel cell (PEMFC) stacks. The water distribution after switch-off of the fuel cell was analyzed over a period of 36 h. We found a slowly increasing water amount in the fuel cell, but only few changes within a time period of 5 h, which is about the time necessary for neutron tomography. In this way, the requirement for successful tomography was obtained. It is demonstrated how the quasi in-situ tomography technique enables us to study the water content in individual flow field channels of three-fold stacks. Flow field as well as stack design issues are addressed by this visualization method showing weak points due to a non-uniform water distribution that can be identified by means of neutron imaging. Amsterdam [u.a.] Elsevier 2012 Journal of power sources 219 120 125 10.1016/j.jpowsour.2012.07.043 2016-02-19 OPUS4-27950 Zeitschriftenartikel Arlt, Tobias; Grothausmann, R.; Manke, I.; Markötter, H.; Hilger, A.; Kardjilov, N.; Tötzke, C.; Banhart, J.; Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Krüger, P.; Haußmann, J.; Hartnig, C.; Wippermann, K. Tomografische Methoden für die Brennstoffzellenforschung Aufgrund des hohen Wirkungsgrades und der vielfältigen Einsatzmöglichkeiten können Brennstoffzellen einen wichtigen Beitrag zur zukünftigen Energieversorgung leisten. Für die Optimierung der Brennstoffzellentechnik ist es erforderlich, die während des Zellbetriebs ablaufenden Prozesse zu verstehen und exakt zu charakterisieren. Ein ausbalanciertes Wassermanagement ist die Grundlage für die optimale Leistungsfähigkeit einer wasserstoffbetriebenen Zelle. Das während des Betriebs entstehende Wasser muss die Membran ausreichend befeuchten, um deren Protonenleitfähigkeit aufrechtzuerhalten. Andererseits behindern zu große Wasseransammlungen in der Zelle die Gaszufuhr durch die porösen Materialien sowie in den Kanälen der Gasverteilerstrukturen. Alterungsphänomene einzelner Zellkomponenten können die Verteilung der Wasseransammlungen und somit das Wassermanagement empfindlich stören und so die Leistungsfähigkeit der Brennstoffzelle herabsetzen. Zur Analyse der Wasserverteilung werden zerstörungsfreie, bildgebende Methoden, wie die Ex-situ-Neutronentomografie und die In-situ-Synchrotronradiografie, eingesetzt. Diese Methoden können während des Brennstoffzellenbetriebs mit weiteren Messverfahren, beispielsweise der ortsaufgelösten Stromdichtemessung, kombiniert werden. Auf diese Weise werden einzelne Komponenten, wie zum Beispiel die Gasdiffusionsschichten, charakterisiert. München Hanser Bundesanstalt für Materialforschung und -prüfung 2013 Materials Testing 55 3 207 213 10.3139/120.110429 2016-02-20 OPUS4-24357 Beitrag zu einem Tagungsband Kupsch, Andreas; Hentschel, Manfred P.; Lange, Axel; Grothausmann, R.; Manke, I. Application of the DIRECTT algorithm to sub-nanometer electron tomography Tomography data obtained from transmission electron microscopes are especially attractive due to their unrivaled spatial resolution in the nanometer range or even less, but they require enormous efforts in sample preparation and suffer from a diverse accumulation of experimental restrictions, which unavoidably result in fundamental reconstruction artifacts. These restrictions refer to: partial opacity, a limited view (limited angle or missing wedge), very few angles (with respect to the detector size), limited to a region of interest (ROI; due to the sample size), variable angular increments as well as sample degradation due the interactions with the electron beam. An advanced version of the DIRECTT (Direct Iterative Reconstruction of Computed Tomography Trajectories) algorithm proves to cope with most of these severe deviations from ideal CT measuring conditions. However, careful data preprocessing is required in order to exploit the capabilities of the algorithm. Nanometer sized Ruthenium catalyst particles for fuel cell applications are 3D imaged at a few Ångström resolution in order to estimate their partial free surface on carbon black supports, which rule the efficiency of the catalytic activity. Comparisons of DIRECTT reconstructions to the conventional filtered back projection, prove the significant improvements. Deutsche Gesellscahft für Zerstörungsfreie Prüfung e.V. (DGZfP) 2011 DIR 2011 - International symposium on digital industrial raidology and computed tomography (Proceedings) 978-3-940283-34-4 DIR 2011 - International symposium on digital industrial raidology and computed tomography Berlin, Germany 20.06.2011 22.06.2011 DGZfP-BB 128 (Tu.3.3) 1 6 urn:nbn:de:kobv:b43-243577 http://creativecommons.org/licenses/by-nd/3.0/de/ 2015-12-31 OPUS4-25075 Posterpräsentation Manke, I. Three-dimensional imaging of magnetic domains 2011 HZB User Meeting 2011 HZB User Meeting 2011 Berlin, Germany 2011-11-30 2011-12-02 2016-02-19 OPUS4-25243 Zeitschriftenartikel Arlt, Tobias; Manke, I.; Wippermann, K.; Tötzke, C.; Markötter, H.; Riesemeier, Heinrich; Mergel, J.; Banhart, J. Investigation of the three-dimensional ruthenium distribution in fresh and aged membrane electrode assemblies with synchrotron X-ray absorption edge tomography Synchrotron X-ray absorption edge imaging was used to investigate the ruthenium distribution in both fresh and aged Pt/Ru-based membrane electrode assemblies (MEA) of direct methanol fuel cells. MEAs aged in different ways were analyzed: artificially aged by MeOH depletion and aged for 1700 h in an operating fuel cell stack. An element sensitive tomographic technique - differential X-ray absorption edge tomography - was applied allowing for a 3D-visualization of the ruthenium distribution within the MEA. We found a markedly changed Ru distribution after aging which is correlated to the GDL structure, the flow field geometry, and CO2 transport in the methanol solution. Amsterdam Elsevier B.V. 2011 Electrochemistry communications 13 8 826 829 10.1016/j.elecom.2011.05.013 2016-02-19 OPUS4-25244 Zeitschriftenartikel Markötter, H.; Manke, I.; Krüger, P.; Arlt, Tobias; Huassmann, J.; Klages, M.; Riesemeier, Heinrich; Hartnig, C.; Scholta, J.; Banhart, J. Investigation of 3D water transport paths in gas diffusion layers by combined in-situ synchrotron X-ray radiography and tomography The three-dimensional water distribution and water transport paths in the gas diffusion layer (GDL) and the adjacent micro-porous layer (MPL) of a polymer electrolyte membrane fuel cell (PEMFC) were analyzed during cell operation. The technique of quasi in-situ X-ray tomography was used for a 3D visualization of the water distribution and the structure of the GDL at different operating conditions. Based on findings from in-situ radiographic measurements water transport paths were detected and subsequently examined by tomography. The combination of these 2D and 3D techniques allows for a fully three-dimensionally resolved visualization of transport paths through the GDL. Amsterdam Elsevier B.V. 2011 Electrochemistry communications 13 9 1001 1004 10.1016/j.elecom.2011.06.023 2016-02-19 OPUS4-25348 Zeitschriftenartikel Tötzke, C.; Manke, I.; Hartnig, C.; Kuhn, R.; Riesemeier, Heinrich; Banhart, J. Investigation of carbon fiber gas diffusion layers by means of synchrotron X-ray tomography The 3-dimensional spatial distribution of liquid water in different gas diffusion layer (GDL) materials was analyzed using synchrotron X-ray tomography. The capability of the method was demonstrated by virtually separating the GDL components in order to facilitate individual analysis of fiber material, liquid water and gas filled pore spaces. The influence of hydrophobic surface treatment on the water distribution in the GDL was illustrated by analyzing three GDL materials with different degrees of hydrophobicity. In the least hydrophobic sample, liquid water tends to form larger clusters which stretch out about several hundred µm inside the porous GDL. In contrast, only small water clusters were found in the strongly hydrophobic material with high Polytetrafluoroethylene (PTFE)-content as the liquid is partially pressed out of the GDL. Additionally, the influence of fiber orientation on the water distribution in the felt material was demonstrated. Pennington, NJ, USA Electrochemical Society 2011 ECS transactions 41 1 379 386 10.1149/1.3635571 2016-02-19 OPUS4-25002 Beitrag zu einem Tagungsband Arlt, Tobias; Grothausmann, R.; Manke, I.; Markötter, H.; Krüger, P.; Haussmann, J.; Hilger, A.; Kardjilov, N.; Hartnig, C.; Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Wippermann, K.; Banhart, J. Tomografische Methoden für die Brennstoffzellenforschung Auf Grund des hohen Wirkungsgrades und der vielfältigen Einsatzmöglichkeiten stellen Brennstoffzellen sowie Brennstoffzellenverbünde eine vielversprechende Energiequelle dar. Daher ist es wichtig, die Prozesse während des Betriebs einer Brennstoffzelle exakt charakterisieren zu können, um diese im nächsten Schritt zu optimieren. So ist ein ausbalanciertes Wassermanagement in einer mit Wasserstoff betriebenen Zelle ausschlaggebend für ihre Leistungsfähigkeit. Für eine dauerhafte Leistungsfähigkeit muss das entstehende Wasser die Membran feucht halten, um so die Protonenleitfähigkeit aufrecht zu erhalten. Zu viel Wasser kann jedoch die Gaszufuhr durch die porösen Materialien in Richtung Membran verhindern. Alterungsphänomene der einzelnen Komponenten können dieses sensible Wassermanagement stören und so die Leistungsfähigkeit einer Brennstoffzelle herabsetzen. Zum tieferen Verständnis der Wasserverteilung werden zerstörungsfreie Methoden, wie zum Beispiel die ex situ Neutronentomografie oder die in situ Synchrotronradiografie eingesetzt. Letztere Methode kann während des Brennstoffzellenbetriebs in Kombination mit weiteren Messmethoden, wie der ortsaufgelösten Stromdichtemessung, eingesetzt werden. So können einzelne Brennstoffzellenkomponenten, wie die Gasdiffusionsschichten, charakterisiert werden. Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) 2011 DGZfP-Jahrestagung 2011 978-3-940283-33-7 DGZfP-Jahrestagung 2011 Bremen, Germany 30.05.2011 01.06.2011 DGZfP-BB 127 (P7) 1 8 urn:nbn:de:kobv:b43-250023 http://creativecommons.org/licenses/by/3.0/de/deed.de 2015-12-31 OPUS4-25004 Beitrag zu einem Tagungsband Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Grothausmann, R.; Manke, I. Verbesserte Elektronen-Tomographie mittels DIRECTT-Algorithmus Tomographische Messungen in Transmissions-Elektronenmikroskopen beziehen ihren Reiz aus der hohen Ortsauflösung im Nanometerbereich. Allerdings bringen sie neben dem hohen Aufwand bei der Probenpräparation auch eine außerordentliche Häufung von Restriktionen der Messung mit sich, die bei Verwendung herkömmlicher Rekonstruktionsalgorithmen zu erheblichen Artefakten führen. Diese Restriktionen betreffen: partielle Nichtdurchstrahlbarkeit, einen eingeschränkten Winkelbereich, wenige Projektionen in Bezug auf die Detektorgröße, Probenabbildungen größer als der Detektor, instabile Rotationsachse, variierende Winkelinkremente sowie Probenveränderungen während der Messung. Der DIRECTT-Algorithmus (Direkte iterative Rekonstruktion computertomographischer Trajektorien) kann, abgesehen von der Probenveränderung, sämtliche dieser Restriktionen geeignet berücksichtigen. Die auftretenden, teils unvollständigen Bahnen lassen sich mittels einer Treffertabelle und geeigneter Auswahl iterativ behandeln. Außerdem kann das Rekonstruktionsvolumen über die Detektorlänge hinaus erweitert werden. Damit gelingt eine weitgehende Unterdrückung von Rekonstruktionsartefakten, insbesondere der sonst dominanten Streifenartefakte, und eine deutliche Erhöhung der Ortsauflösung. Die Verbesserung der Rekonstruktionsqualität wird anhand von Modell- und experimentellen Daten gezeigt. Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) 2011 DGZfP-Jahrestagung 2011 978-3-940283-33-7 DGZfP-Jahrestagung 2011 Bremen, Germany 30.05.2011 01.06.2011 DGZfP-BB 127 (P8) 1 7 http://creativecommons.org/licenses/by-nd/3.0/de/ 2015-12-31 OPUS4-26282 Zeitschriftenartikel Markötter, H.; Manke, I.; Haußmann, J.; Arlt, Tobias; Klages, M.; Krüger, P.; Hartnig, C.; Scholta, J.; Müller, Bernd R.; Riesemeier, Heinrich; Banhart, J. Combined synchrotron X-ray radiography and tomography study of water transport in gas diffusion layers Synchrotron X-ray radiography and tomography investigations of a custom-made polymer electrolyte membrane fuel cell optimised for visualisation purposes are presented. The 3D water distribution and transport pathways in the porous carbon fibre gas diffusion layers (GDLs) were investigated. The authors found that water is not only moving from the GDL into the channel, but can also take the opposite way, that is, from the channel into free pore space of the GDL. Such movement of water into the opposite direction has been subject of speculations but has so far not yet been reported and might bring new insights into the general water transport behaviour, which might give new aspects to the general description of water transport processes and influence modelling assumptions to describe the process taking place in the GDL. London IET Institution of Engineering and Technology 2012 Micro & nano letters 7 7 689 692 10.1049/mnl.2012.0410 2016-02-19 OPUS4-18566 Zeitschriftenartikel Zabler, S.; Rack, A.; Manke, I.; Thermann, K.; Tiedemann, J.; Harthill, N.; Riesemeier, Heinrich High-resolution tomography of cracks, voids and micro-structure in greywacke and limestone Rocks are commonly very heterogeneous materials. Randomly distributed micro-flaws inside the rock are believed to initiate tensile cracks from which shear fractures develop and coalescence through en echelon interactions leads to fracture. In this paper, we describe the results of applying high-resolution X-ray tomography to samples of greywacke and limestone experimentally deformed under unconfined axial shortening at various loads equivalent to different fractions of the sample strength. Mineral grains, pores, micro-cracks and other voids were imaged with a resolution of 10 µm. 3D image analysis enabled us to monitor the initial state of the samples and the changes in them due to compression. Crack morphology is characterized and compared to the micro-structure of the sample before and after deformation. In the greywacke, formation of a macro-crack ~10° oblique to the stress direction is observed. It initiated in fine intergranular material at the top tip of the sample and is composed of tensile fractures connected by wing cracks. None of the voids defined in the initial state fractured, and the crack is interpreted to have started either as a micro-crack which was smaller than the resolution of the tomography, or, as a completely new crack. In the limestone, cracks are observed to initiate in features that are too small to be imaged by the tomography, or also in newly created cracks. Oxford Pergamon Press 2008 Journal of structural geology 30 7 876 887 10.1016/j.jsg.2008.03.002 2016-02-19 OPUS4-29506 Beitrag zu einem Tagungsband Griesche, Axel; Dabah, Eitan; Hilger, A.; Kardjilov, N.; Manke, I.; Kannengießer, Thomas Neutron imaging of hydrogen in steels Red Hook, NY Curran American Ceramic Society 2013 Materials Science & Technology (MS&T) 2013 (Proceedings) Materials Science & Technology (MS&T) 2013 Montreal, Quebec, Canada 2013-10-27 2013-10-31 945 950 2016-02-20 OPUS4-18656 Zeitschriftenartikel Hartnig, C.; Kuhn, R.; Krüger, P.; Manke, I.; Kardjilov, N.; Goebbels, Jürgen; Müller, Bernd R.; Riesemeier, Heinrich Wassermanagement in Brennstoffzellen - die Bedeutung von hochauflösenden zerstörungsfreien Untersuchungsmethoden Ein effektives Wassermanagement ist ein wichtiger Aspekt in der Entwicklung von Brennstoffzellen hinsichtlich Langzeitstabilität und Optimierung der Leistungsfähigkeit. Eine zentrale Rolle spielt dabei die Gasdiffusionslage, die für die gleichmäßige Verteilung der Reaktionsgase auf die elektrochemisch aktive Schicht (Katalysator) sorgen soll. In diesem Beitrag werden gemeinsame Forschungsaktivitäten des Helmholtz-Zentrums Berlin für Materialien und Energie (Entwicklung bildgebender Verfahren) sowie des Zentrums für Sonnenenergie- und Wasserstoff-Forschung (ZSW, Entwicklung von Brennstoffzellen) vorgestellt. Im Rahmen dieser Kooperation werden die Entstehung, die Verteilung und der Transport von flüssigem Wasser, kurz das Wassermanagement, unter Betriebsbedingungen untersucht. Mittels Synchrotronradiografie und -tomografie werden kleinste Wassercluster in der Gasdiffusionslage detektiert. Die gewonnenen Erkenntnisse dienen der Modifikation und einer gezielten Auswahl der eingesetzten Materialien. München Hanser Bundesanstalt für Materialforschung und -prüfung 2008 MP materials testing 50 10 609 614 2016-02-19 OPUS4-19221 Zeitschriftenartikel Manke, I.; Hartnig, C.; Kardjilov, N.; Hilger, A.; Lange, Axel; Kupsch, Andreas; Banhart, J. Wasserverteilung in PEM-Brennstoffzellen - In-situ-Untersuchung mit Neutronenradiografie und -tomografie In-situ-Neutronenradiografie wird erfolgreich eingesetzt, um flüssiges Wasser in Niedertemperatur-PEM-Brennstoffzellen während des Betriebs zerstörungsfrei abzubilden und das sogenannte Wassermanagement – eine der größten Herausforderungen der Entwicklung – durch Anpassung der Materialeigenschaften zu optimieren. Dabei werden die besonderen Eigenschaften der Neutronen genutzt, die metallische Bauteile relativ leicht durchdringen, während selbst kleine Wassermengen durch ihre starke Streuung leicht nachweisbar sind. Die relativ langen Messzeiten für die Neutronentomografie werden durch den Betrieb der Zelle im “angehaltenen” Zustand realisierbar, sodass die dreidimensionale Wasserverteilung darstellbar wird. München Hanser Bundesanstalt für Materialforschung und -prüfung 2009 MP materials testing 51 4 219 226 2016-02-19 OPUS4-21864 Beitrag zu einem Tagungsband Lange, Axel; Hentschel, Manfred P.; Kupsch, Andreas; Manke, I.; Kardjilov, N.; Arlt, Tobias; Grothausmann, R. Rekonstruktion limitierter CT-Datensätze von Brennstoffzellen mit DIRECTT Berlin Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. (DGZfP) 2010 DGZfP-Jahrestagung 2010 978-3-940283-26-9 DGZfP-Jahrestagung 2010 Erfurt, Deutschland 2010-05-10 2010-05-12 DGZfP-BB 122 (Mi.1.B.3) 1 11 2016-02-19 OPUS4-22730 Zeitschriftenartikel Manke, I.; Hartnig, C.; Kardjilov, N.; Riesemeier, Heinrich; Goebbels, Jürgen; Kuhn, R.; Krüger, P.; Banhart, J. In situ synchrotron X-ray radiography investigations of water transport in PEM fuel cells Water transport in an operating PEM fuel cell was investigated with synchrotron X-ray radiography with a spatial resolution of 3 µm and a temporal resolution of 5 s. This method allows for the detection of water accumulations with less than 10 µm diameter. We demonstrate that synchrotron X-ray imaging can dramatically expand the possibilities of imaging with high spatial and time resolution, especially as a complement to neutron radiography. Water transport processes from the first appearance of small water accumulations in the gas diffusion layer to their transport into the channel system were analysed in situ. Correlations between local effects such as water formation and operating conditions of the whole system, e.g. power variations, were found. A recently described eruptive water transport mechanism is analysed in detail. Weinheim Wiley-VCH 2010 Fuel Cells 10 1 26 34 10.1002/fuce.200800123 2016-02-19 OPUS4-22070 Zeitschriftenartikel Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Manke, I.; Kardjilov, N.; Arlt, Tobias; Grothausmann, R. Rekonstruktion limitierter CT-Messdatensätze von Brennstoffzellen mit Directt Die Aufklärung spezifischer Fragestellungen zur Funktionalität von PEM(polymer electrolyte membrane)- und DMFC(Direct Methanol)-Brennstoffzellen bedarf der 3D-Abbildung der spezifischen Komponenten mit unterschiedlichen Strahlungsarten: des Wassergehalts in den Flow Fields mit Neutronen, der Katalysator-Alterung in der MEA (membrane electrode assembly) mit Synchrotronstrahlung und der freien (reaktiven) Katalysator-Oberfläche von Nano-Partikeln mit TEM-Elektronen-Tomografie. Diese Messungen im Bereich der mm- bis nm-Skala unterliegen dabei erheblichen Restriktionen: einer ortsabhängigen Verschmierung der Neutronenradiogramme, Manipulatorinstabilitäten der Synchrotronmessungen sowie einer Kombination von Limited-View-Datensätzen, wenigen Projektionswinkeln und teilweiser Nichtdurchstrahlbarkeit in der Elektronen-CT. Die Vorteile eines fortentwickelten Directt-Algorithmus für die Bewältigung dieser Randbedingungen gegenüber gefilterten Rückprojektionen werden aufgezeigt. München Hanser Bundesanstalt für Materialforschung und -prüfung 2010 MP materials testing 52 10 676 683 2016-02-19 OPUS4-25833 Beitrag zu einem Tagungsband Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Grothausmann, R.; Arlt, Tobias; Manke, I. High quality reconstruction of insufficient tomographic data by a new iterative procedure In order to demonstrate the challenging tasks in current R&D applications in the field of renewable energy sources experimental neutron and electron tomographic data sets of PEM fuel cell components are processed by an advanced version of the DIRECTT algorithm. The neutron measurements of the water distribution suffer from several intrinsic limitations such as massive position dependent focal smearing due to the large primary neutron beam aperture. Electron (TEM) tomography allows characterisation of nanometre sized catalyst particles but is hampered by the following restrictions: partial opacity, a limited sector of projections (missing wedge), very few projections, samples exceeding the detector size (region of interest) and improper angular alignment. Beyond the capabilities of other algorithms DIRECTT proves to overcome these essential reconstruction problems, in comparison to FBP and SIRT. Nevertheless, careful data pre-processing is an inevitable requirement in order to fully exploit the algorithm's potentials. 2012 18th WCNDT - World conference on nondestructive testing (Proceedings) 978-0-620-52872-6 18th WCNDT - World conference on nondestructive testing Durban, South Africa 2012-04-16 2012-04-20 1 8(?) 2016-02-19 OPUS4-25834 Beitrag zu einem Tagungsband Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Lück, S.; Schmidt, V.; Hilger, A.; Garcia-Moreno, F.; Manke, I. Reconstruction of limited view tomography data by DIRECTT Incomplete tomographic data sets such as limited view (missing wedge) data represent a well-known challenge for reconstruction algorithms, since they unavoidably lead to substantial image artefacts. Such data sets may occur in industrial computed tomography of limited access (e.g. extended components, fixed objects), directional opacity, limited sample life time or laminographic set-up. We present strategies to effectively suppress the typical elongation artefacts (e.g. lemon-like deformed pores) by our iterative algorithm DIRECTT which offers the opportunity to vary the versatile reconstruction parameters within each cycle. Those strategies are applied to experimental data obtained from metallic foams as well as model simulations. Comparison is drawn to state-ofthe- art techniques (filtered backprojection and algebraic techniques). Further reference is made to reconstructions of complete data sets serving as gold standards. For quantitative assessment of the reconstruction quality adapted techniques based on spatial statistics are introduced. 2012 18th WCNDT - World conference on nondestructive testing (Proceedings) 978-0-620-52872-6 18th WCNDT - World conference on nondestructive testing Durban, South Africa 2012-04-16 2012-04-20 1 9(?) 2016-02-19 OPUS4-26433 Zeitschriftenartikel Williams, S. H.; Hilger, A.; Kardjilov, N.; Manke, I.; Strobl, M.; Douissard, P.A.; Martin, T.; Riesemeier, Heinrich; Banhart, J. Detection system for microimaging with neutrons A new high-resolution detector setup for neutron imaging has been developed based on infinity-corrected optics with high light collection, combined with customized mounting hardware. The system can easily be installed, handled and fitted to any existing facility, avoiding the necessity of complex optical systems or further improved electronics (CCD). This is the first time optical magnification higher than 1:1 has been used with scintillator-based neutron detectors, as well as the first implementation of infinity corrected optics for neutron imaging, achieving the smallest yet reported effective pixel size of 3.375 µm. A novel transparent crystal scintillator (GGG crystal) has been implemented with neutrons for the first time to overcome limitations of traditional powder scintillators (Li6/ZnS, Gadox). The standardized procedure for resolution measurements with the Modulation Transfer Function (MTF) is summarized to facilitate comparison between instruments and facilities. Using this new detector setup, a resolution of 14.8 µm with a field of view of 6 mm × 6 mm has been achieved while maintaining reasonable count times. These advances open a wide range of new possible research applications and allow the potential for additional future developments. London Inst. of Physics Publ. 2012 Journal of Instrumentation 7 P02014 1 26 10.1088/1748-0221/7/02/P02014 2016-02-19 OPUS4-26434 Zeitschriftenartikel Markötter, H.; Alink, R.; Haußmann, J.; Dittmann, K.; Arlt, Tobias; Wieder, F.; Tötzke, C.; Klages, M.; Reiter, C.; Riesemeier, Heinrich; Scholta, J.; Gerteisen, D.; Banhart, J.; Manke, I. Visualization of the water distribution in perforated gas diffusion layers by means of synchrotron X-ray radiography Perforated gas diffusion layers (GDLs) of polymer electrolyte membrane fuel cells (PEMFCs) were investigated by means of in-situ synchrotron X-ray radiography during operation. We found a strong influence of perforations on the water distribution and transport in the investigated Toray TGP-H-090 GDL. The water occurs mainly around the perforations, while the holes themselves show varying water distributions. Some remain dry, while most of them fill up with liquid water after a certain period or might serve as drainage volume for effective water transport. Oxford Elsevier International Association for Hydrogen Energy 2012 International journal of hydrogen energy 37 9 7757 7761 10.1016/j.ijhydene.2012.01.141 2016-02-19 OPUS4-27372 Zeitschriftenartikel Arlt, Tobias; Manke, I.; Wippermann, K.; Riesemeier, Heinrich; Mergel, J.; Banhart, J. Investigation of the local catalyst distribution in an aged direct methanol fuel cell MEA by means of differential synchrotron X-ray absorption edge imaging with high energy resolution Synchrotron X-ray absorption edge imaging with high energy resolution was applied to study aging of fuel cell catalyst materials. The combination of an imaging and a high X-ray energy resolution set-up allows acquiring spatially resolved XAS (XANES and EXAFS) spectra. We analyzed the two-dimensional distribution of Pt and Ru in fresh and aged fuel cell catalysts. Spatially resolved XAS images were taken at the RuK edge and at the PtL3 edge. Taking radiographs above and below the absorption edges provides quantitative information about the thickness of the catalytic materials and additional chemical information. A strong influence of the flow field channels and the structure of the gas diffusion layers on the thicknesses of the catalytic elements were found: a thinner catalyst layer was found below the ribs of the flow field geometries as well as under crossing points of fiber bundles of the woven gas diffusion layers. Amsterdam [u.a.] Elsevier 2013 Journal of power sources 221 210 216 10.1016/j.jpowsour.2012.08.038 2016-02-20 OPUS4-29979 Zeitschriftenartikel Tötzke, C.; Gaiselmann, G.; Osenberg, M.; Bohner, J.; Arlt, Tobias; Markötter, H.; Hilger, A.; Wieder, F.; Kupsch, Andreas; Müller, Bernd R.; Hentschel, Manfred P.; Banhart, J.; Schmidt, V.; Lehnert, W.; Manke, I. Three-dimensional study of compressed gas diffusion layers using synchrotron X-ray imaging We present a synchrotron X-ray tomographic study on the morphology of carbon fiber-based gas diffusion layer (GDL) material under compression. A dedicated compression device is used to provide well-defined compression conditions. A flat compression punch is employed to study the fiber geometry at different degrees of compression. Transport relevant geometrical parameters such as porosity, pore size and tortuosity distributions are calculated. The geometric properties notably change upon compression which has direct impact on transport conditions for gas and fluid flow. The availability of broad 3D paths, which are most important for the transport of liquid water from the catalyst layer through the GDL, is markedly reduced after compression. In a second experiment, we study the influence of the channel-land-pattern of the flow-field on shape and microstructure of the GDL. A flow-field compression punch is employed to reproduce the inhomogeneous compression conditions found during fuel cell assembly. While homogenously compressed underneath the land the GDL is much less and inhomogeneously compressed under the channel. The GDL material extends far into the channel volume where it can considerably influence gas and fluid flow. Loose fiber endings penetrate deeply into the channel and form obstacles for the discharge of liquid water droplets. Amsterdam [u.a.] Elsevier 2014 Journal of power sources 253 123 131 10.1016/j.jpowsour.2013.12.062 2016-02-20 OPUS4-56164 Zeitschriftenartikel Van Tran, K.; Woracek, R.; Kardjilov, N.; Markötter, Henning; Abou-Ras, D.; Puplampu, S.; Förster, C.; Penumadu, D.; Dahlberg, C. F. O.; Banhart, J.; Manke, I. Torsion of a rectangular bar: Complex phase distribution in 304L steel revealed by neutron tomography Metastable austenitic stainless steel (304L) samples with a rectangular cross-section were plastically deformed in torsion during which they experienced multiaxial stresses that led to a complex martensitic phase distribution owing to the transformation induced plasticity effect. A three-dimensional characterization of the phase distributions in these cm-sized samples was carried out by wavelength-selective neutron tomography. It was found that quantitatively correct results are obtained as long as the samples do not exhibit any considerable preferential grain orientation. Optical microscopy, electron backscatter diffraction, and finite element modeling were used to verify and explain the results obtained by neutron tomography. Altogether, neutron tomography was shown to extend the range of microstructure characterization methods towards the meso- and macroscale. Elsevier Ltd. 2022 Materials & Design 222 111037 urn:nbn:de:kobv:b43-561649 10.1016/j.matdes.2022.111037 https://creativecommons.org/licenses/by/4.0/deed.de 2022-11-03 OPUS4-56457 Zeitschriftenartikel Zhang, Z.; Dong, K.; Mazzio, K. A.; Hilger, A.; Markötter, Henning; Wilde, F.; Heinemann, T.; Manke, I.; Adelhelm, P. Phase transformation and microstructural evolution of CuS electrodes in solid-state batteries probed by in situ 3D X-ray tomography Copper sulfide shows some unique physico-chemical properties that make it appealing as a cathode active material (CAM) for solid-state batteries (SSBs). The most peculiar feature of the electrode reaction is the reversible formation of μm-sized Cu crystals during cycling, despite its large theoretical volume change (75%). Here, the dynamic microstructural evolution of CuS cathodes in SSBs is studied using in situ synchrotron X-ray tomography. The formation of μm-sized Cu within the CAM particles can be clearly followed. This process is accompanied by crack formation that can be prevented by increasing the stack pressure from 26 to 40 MPa. Both the Cu inclusions and cracks show a preferential orientation perpendicular to the cell stack pressure, which can be a result of a z-oriented expansion of the CAM particles during lithiation. In addition, cycling leads to a z-oriented reversible displacement of the cathode pellet, which is linked to the plating/stripping of the Li counter electrode. The pronounced structural changes cause pressure changes of up to 6 MPa within the cell, as determined by operando stack pressure measurements. Reasons for the reversibility of the electrode reaction are discussed and are attributed to the favorable combination of soft materials. Wiley VHC-Verlag 2022 Advanced Energy Materials 2203143 1 12 urn:nbn:de:kobv:b43-564577 10.1002/aenm.202203143 https://creativecommons.org/licenses/by/4.0/deed.de 2022-12-05 OPUS4-54597 Zeitschriftenartikel Ziesche, R.F.; Hack, J.; Rasha, L.; Maier, M.; Tan, C.; Heenan, T.M.M.; Markötter, Henning; Kardjilov, N.; Manke, I.; Kockelmann, W.; Brett, D.J.L.; Shearing, P.R. High-speed 4D neutron computed tomography for quantifying water dynamics in polymer electrolyte fuel cells In recent years, low-temperature polymer electrolyte fuel cells have become an increasingly important pillar in a zero-carbon strategy for curbing climate change, with their potential to power multiscale stationary and mobile applications. The performance improvement is a particular focus of research and engineering roadmaps, with water management being one of the major areas of interest for development. Appropriate characterisation tools for mapping the evolution, motion and removal of water are of high importance to tackle shortcomings. This article demonstrates the development of a 4D high-speed neutron imaging technique, which enables a quantitative analysis of the local water evolution. 4D visualisation allows the time-resolved studies of droplet formation in the flow fields and water quantification in various cell parts. Performance parameters for water management are identified that offer a method of cell classification, which will, in turn, support computer modelling and the engineering of next-generation flow field designs. London Nature Publishing Group UK 2022 Nature Communications 13 1 1616 urn:nbn:de:kobv:b43-545978 10.1038/s41467-022-29313-5 https://creativecommons.org/licenses/by/4.0/deed.de 2022-04-06 OPUS4-54431 Zeitschriftenartikel Sun, F.; Wang, C.; Osenberg, M.; Dong, K.; Zhang, S.; Yang, C.; Wang, Y.; Hilger, A.; Zhang, J.; Dong, S.; Markötter, Henning; Manke, I.; Cui, G. Clarifying the Electro-Chemo-Mechanical Coupling in Li10SnP2S12 based All-Solid-State Batteries A fundamental clarification of the electro-chemo-mechanical coupling at the solid-solid electrode|electrolyte interface in all-solid-state batteries (ASSBs) is of crucial significance but has proven challenging. Herein, (synchrotron) X-ray tomography, electrochemical impedance spectroscopy (EIS), time-of-flight secondary-ion mass spectrometry (TOF-SIMS), and finite element analysis (FEA) modeling are jointly used to decouple the electro-chemo-mechanical coupling in Li10SnP2S12-based ASSBs. Non-destructive (synchrotron) X-ray tomography results visually disclose unexpected mechanical deformation of the solid electrolyte and electrode as well as an unanticipated evolving behavior of the (electro)chemically generated interphase. The EIS and TOFSIMS probing results provide additional information that links the interphase/electrode properties to the overall battery performance. The modeling results complete the picture by providing the detailed distribution of the mechanical stress/strain and the potential/ionic flux within the electrolyte. Collectively, these results suggest that 1) the interfacial volume changes induced by the (electro)chemical reactions can trigger the mechanical deformation of the solid electrode and electrolyte; 2) the overall electrochemical process can accelerate the interfacial chemical reactions; 3) the reconfigured interfaces in turn influence the electric potential distribution as well as charge transportation within the SE. These fundamental discoveries that remain unreported until now significantly improve the understanding of the complicated electro-chemo-mechanical couplings in ASSBs. Wiley VHC-Verlag 2022 Advanced Energy Materials 2103714 10.1002/aenm.202103714 2022-03-09 OPUS4-53836 Zeitschriftenartikel Duan, K.; Zhu, L.; Li, M.; Xiao, L.; Bevilacqua, N.; Eifert, L.; Manke, I.; Markötter, Henning; Zhang, R.; Zeis, R.; Sui, P. -C. Multiphase and Pore Scale Modeling on Catalyst Layer of High-Temperature Polymer Electrolyte Membrane Fuel Cell Phosphoric acid as the electrolyte in high-temperature polymer electrolyte membrane fuel cell plays an essential role in ist performance and lifetime. Maldistribution of phosphoric acid in the catalyst layer (CL) may result in performance degradation. In the present study, pore-scale simulations were carried out to investigate phosphoric acid's multiphase flow in a cathode CL. A reconstructed CL model was built using focused ion beam-SEM images, where distributions of pore, carbon support, binder, and catalyst particles can be identified. The multi-relaxation time lattice Boltzmann method was employed to simulate phosphoric Acid invading and leaching from the membrane into the CL during the membrane electrode assembly fabrication process. The predicted redistribution of phosphoric acid indicates that phosphoric acid of low viscosity or low wettability is prone to leaching into the CL. The effective transport properties and the active electrochemical active surface area (ECSA) were computed using a pore-scale model. They were subsequently used in a macroscopic model to evaluate the cell performance. A parametric study shows that cell performance first increases with increasing phosphoric acid content due to the increase of ECSA. However, further increasing phosphoric acid content results in performance degradation due to mass transfer limitation caused by acid flooding. IOP Science 2021 Journal of The Electrochemical Society 168 5 054521 10.1149/1945-7111/abff03 2021-11-29 OPUS4-53077 Zeitschriftenartikel Hilger, A.; Kardjilov, N.; Lange, A.; Kupsch, Andreas; Hentschel, M. P.; Manke, I. Neutron darkfield imaging of fiber composites While X-ray based darkfield imaging with grating interferometers is already widely used, darkfield imaging with neutrons has still a relatively small user community focused mostly on magnetic materials. Here, we demonstrate the application of neutron darkfield imaging byTalbot-Lau type grating interferometry to fiber reinforced plastics. Common carbon and glass fiber composites have been investigated including characteristic damage structures. The darkfield images show a strong signal response caused by fiber delamination, suitable fiber direction, particles, pores and cracks. The basic principles of neutron darkfield imaging applied to fiber composites are highlighted. Berlin De Gruyter 2021 Materials Testing 63 7 623 629 10.1515/mt-2020-0103 2021-08-11 OPUS4-52089 Zeitschriftenartikel Ziesche, R. F.; Robinson, J. B.; Markötter, Henning; Bradbury, R.; Tengattini, A.; Lenoir, N.; Helfen, L.; Kockelmann, W.; Kardjilov, N.; Manke, I.; Brett, D. J. L.; Shearing, P. R. Editors' Choice—4D Neutron and X-ray Tomography Studies of High Energy Density Primary Batteries: Part II. Multi-Modal Microscopy of LiSOCl2 Cells The ability to track electrode degradation, both spatially and temporally, is fundamental to understand performance loss during operation of lithium batteries. X-ray computed tomography can be used to follow structural and morphological changes in electrodes; however, the direct detection of electrochemical processes related to metallic lithium is difficult due to the low sensitivity to the element. In this work, 4-dimensional neutron computed tomography, which shows high contrast for lithium, is used to directly quantify the lithium diffusion process in spirally wound Li/SOCl2 primary cells. The neutron dataset enables the quantification of the lithium transport from the anode and the accumulation inside the SOCl2 cathode to be locally resolved. Complementarity between the collected neutron and X-ray computed tomographies is shown and by applying both methods in concert we have observed lithium diffusion blocking by the LiCl protection layer and identified all cell components which are difficult to distinguish using one of the methods alone. IOP Science 2020 Journal of the Electrochemical Society 167 140509 urn:nbn:de:kobv:b43-520890 10.1149/1945-7111/abbfd9 https://creativecommons.org/licenses/by/4.0/deed.de 2021-02-10 OPUS4-52091 Zeitschriftenartikel Bevilacqua, N.; Asset, T.; Schmid, M. A.; Markötter, Henning; Manke, I.; Atanassov, P.; Zeis, R. Impact of catalyst layer morphology on the operation of high temperature PEM fuel cells Electrochemical impedance spectroscopy (EIS) is a well-established method to analyze a polymer electrolyte membrane fuel cell (PEMFC). However, without further data processing, the impedance spectrum yields only qualitative insight into the mechanism and individual contribution of transport, kinetics, and ohmic losses to the overall fuel cell limitations. The distribution of relaxation times (DRT) method allows quantifying each of these polarization losses and evaluates their contribution to a given electrocatalyst's depreciated performances. We coupled this method with a detailed morphology study to investigate the impact of the 3D-structure on the processes occurring inside a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC). We tested a platinum catalyst (Pt/C), a platinum-cobalt alloy catalyst (Pt3Co/C), and a platinum group metal-free iron-nitrogen-carbon (Fe-N-C) catalyst. We found that the hampered mass transport in the latter is mainly responsible for its low performance in the MEA (along with its decreased intrinsic performances for the ORR reaction). The better performance of the alloy catalyst can be explained by both improved mass transport and a lower ORR resistance. Furthermore, single-cell tests show that the catalyst layer morphology influences the distribution of phosphoric acid during conditioning. Elsevier Ltd. 2021 Journal of Power Sources Advances 7 100042 urn:nbn:de:kobv:b43-520917 10.1016/j.powera.2020.100042 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2021-02-10 OPUS4-56805 Zeitschriftenartikel Pacheco, V.; Marattukalam, J. J.; Karlsson, D.; Dessieux, L.; Tran, K. V.; Beran, P.; Manke, I.; Kardjilov, N.; Markötter, Henning; Sahlberg, M.; Woracek, R. On the relationship between laser scan strategy, texture variations and hidden nucleation sites for failure in laser powder-bed fusion While laser powder-bed fusion has overcome some of the design constraints of conventional manufacturing methods, it requires careful selection of process parameters and scan strategies to obtain favorable properties. Here we show that even simple scan strategies, complex ones being inevitable when printing intricate designs, can inadvertently produce local alterations of the microstructure and preferential grain orientation over small areas - which easily remain unnoticed across the macroscale. We describe how a combined usage of neutron imaging and electron backscatter diffraction can reveal these localized variations and explain their origin within cm-sized parts. We explain the observed contrast variations by linking the neutron images to simulated data, pole figures and EBSD, providing an invaluable reference for future studies and showing that presumably minor changes of the scan strategy can have detrimental effects on the mechanical properties. In-situ tensile tests reveal that fracture occurs in a region that was re-melted during the building process. Elsevier B.V. 2022 Materialia 26 1 9 urn:nbn:de:kobv:b43-568054 10.1016/j.mtla.2022.101614 https://creativecommons.org/licenses/by/4.0/deed.de 2023-01-09 OPUS4-37323 Beitrag zu einem Tagungsband Kardjilov, N.; Hilger, A.; Manke, I.; Banhart, J.; Griesche, Axel Imaging with Cold Neutrons at the CONRAD-2 Facility CONRAD-2 is an imaging instrument using low-energy (cold) neutrons. The instrument is installed at the end of a curved neutron guide which avoids the direct line of sight towards the reactor core. This ensures a very low background of high-energy neutrons and. photons at the sample position. The cold neutron beam provides a wavelength range which is suitable for phase-and diffraction-contrast imaging such as grating interferometry and Bragg edge mapping. The instrument is well suited for high resolution imaging due to the high efficiency of the very thin scintillators that can be used for the detection of cold neutrons. An instrument upgrade was performed recently as a part of an upgrade program for the cold neutron instrumentation at HZB. The parameters of the instrument as well as some research highlights will be presented. Amsterdam, NL Elsevier B.V. 2015 Physics Procedia 69 10th World Conference on Neutron Radiography (WCNR) Grindelwald, SWITZERLAND 05.10.2014 10.10.2014 60 66 urn:nbn:de:kobv:b43-373239 10.1016/j.phpro.2015.07.008 http://creativecommons.org/licenses/by-nc-nd/3.0/de/deed.de 2016-09-13 OPUS4-36918 Zeitschriftenartikel Tötzke, C.; Gaiselmann, G.; Osenberg, M.; Arlt, Tobias; Markötter, H.; Hilger, A.; Kupsch, Andreas; Müller, Bernd R.; Schmidt, V.; Lehnert, W.; Manke, I. Influence of hydrophobic treatment on the structure of compressed gas diffusion layers Carbon fiber based felt materials are widely used as gas diffusion layer (GDL) in fuel cells. Their transport properties can be adjusted by adding hydrophobic agents such as polytetrafluoroethylene (PTFE). We present a synchrotron X-ray tomographic study on the felt material Freudenberg H2315 with different PTFE finishing. In this study, we analyze changes in microstructure and shape of GDLs at increasing degree of compression which are related to their specific PTFE load. A dedicated compression device mimicking the channel-land pattern of the flowfield is used to reproduce the inhomogeneous compression found in a fuel cell. Transport relevant geometrical parameters such as porosity, pore size distribution and geometric tortuosity are calculated and consequences for media transport discussed. PTFE finishing results in a marked change of shape of compressed GDLs: surface is smoothed and the invasion of GDL fibers into the flow field channel strongly mitigated. Furthermore, the PTFE impacts the microstructure of the compressed GDL. The number of available wide transport paths is significantly increased as compared to the untreated material. These changes improve the transport capacity liquid water through the GDL and promote the discharge of liquid water droplets from the cell. Amsterdam Elsevier 2016 Journal of Power Sources 324 625 636 10.1016/j.jpowsour.2016.05.118 2016-07-20 OPUS4-31377 Zeitschriftenartikel Lange, Axel; Hentschel, Manfred P.; Kupsch, Andreas; Hilger, A.; Manke, I.; Lück, S.; Schmidt, V.; Grothausmann, R. Reduzierung von Missing-Wedge-Artefakten der CT mit DIRECTT Typische 'Missing Wedge'(MW)-Artefakte in Rekonstruktionen der Computertomografie können mit dem iterativen DIRECTT-Algorithmus (Direkte iterative Rekonstruktion computertomografischer Trajektorien) unterdrückt werden. Die durch fehlende Projektionswinkel bedingten MW-Restriktionen betreffen bisher nur Sonderapplikationen der Röntgen- und Neutronentomografie, müssen in der Nanometer auflösenden Elektronentomografie jedoch als Standard akzeptiert werden. Die MW-Artefakte werden besonders effektiv mit einer spezifischen DIRECTT-Prozedur partiell diskreter Zwischenlösungen beseitigt. Für die Beurteilung der Abbildungsqualität werden Rekonstruktionen von vollständigen und unvollständigen Mess- und Modell-Datensätzen erzeugt und mit Ergebnissen anderer Algorithmen (gefilterte Rückprojektion (FBP) und ART-Methoden) verglichen. Die Fourier-Transformierten der Rekonstruktionen demonstrieren die erfolgreiche Ergänzung der fehlenden Information im MW-Bereich. Die quantitative Bewertung der lokalen Rekonstruktionsqualität mit Methoden der räumlichen Statistik ergibt auch für unterschiedliche Signal-Rausch-Verhältnisse signifikante Vorteile gegenüber FBP und ART. München Hanser Bundesanstalt für Materialforschung und -prüfung 2014 Materials Testing 56 9 716 721 2016-02-20 OPUS4-31297 Beitrag zu einem Tagungsband Lange, Axel; Kupsch, Andreas; Hentschel, Manfred P.; Lück, S.; Schmidt, V.; Grothausmann, R.; Hilger, A.; Manke, I. Reduzierung von Missing-Wedge-Artefakten mit DIRECTT Wir stellen eine Prozedur vor, mit der typische 'Missing Wedge' (MW)-Artefakte in CT-Rekonstruktionen effektiv unterdrückt werden können. Dazu wird der iterative DIRECTT-Algorithmus (Direkte Iterative Rekonstruktion Computertomographischer Trajektorien) mit einigen Zyklen diskreter Rekonstruktion eingesetzt. Die Kernfunktionen des Algorithmus', die wiederholte Auswahl und Gewichtung von Elementen einer Zwischenkonstruktion, werden beibehalten. Abgesehen von Sonderfällen der Röntgen- und Neutronentomographie tritt die MW-Restriktion (neben einer Vielzahl anderer) in Standardkonfigurationen der Elektronentomographie auf. Um den MW-Effekt isoliert zu untersuchen und beurteilen zu können, werden hier vollständige experimentelle Datensätze einer bekannten Porenstruktur um einen Sektor beschnitten sowie MW-Rekonstruktionen von Porenmodellen erzeugt. Die Ergebnisse werden mit zurzeit verbreiteten Algorithmen (Gefilterte Rückprojektion (FBP) und ART-Varianten) verglichen. Die Bewertung im Fourierraum zeigt, dass DIRECTT die fehlende Information im MW erfolgreich ergänzt. Zur quantitativen Bewertung der lokalen Rekonstruktionsqualität werden Methoden der räumlichen Statistik eingesetzt. Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) 2014 DGZfP-Jahrestagung 2014 (Proceedings) 978-3-940283-61-0 DGZfP-Jahrestagung 2014 Potsdam, Germany 26.05.2014 28.05.2014 DGZfP-BB 148 Poster 18, 1 8 urn:nbn:de:kobv:b43-312977 http://creativecommons.org/licenses/by-nd/3.0/de/ 2015-12-31 OPUS4-30545 Zeitschriftenartikel Markötter, H.; Haußmann, J.; Alink, R.; Dittmann, K.; Tötzke, C.; Krüger, P.; Klages, M.; Arlt, Tobias; Müller, Bernd R.; Riesemeier, Heinrich; Scholta, J.; Gerteisen, D.; Manke, I.; Banhart, J. Investigation of fuel cell materials and liquid water transport by means of synchrotron imaging Synchrotron imaging allows addressing various important issues in fuel cell research, for example water distribution and transport. The water distribution in polymer electrolyte membrane fuel cells (PEMFCs) was observed quasi in-situ directly after operation by means of synchrotron tomography. The 3D data set was compared with the tomogram of a dry cell in order to separate the water distribution from cell materials. Engineered transport pathways realized by perforating holes through the gas diffusion layer (GDL) are a recent approach to optimize water transport and cell performance. For some parameter sets a cell performance increase and an improvement of stabilization have already been proven. We present high resolution investigations of the water distribution in perforated GDLs of operating PEMFCs by means of in-situ synchrotron radiography. The surrounding areas of the holes exhibited a distinct hydrophilic character. Pennington, NJ, USA Electrochemical Society 2013 ECS transactions 45 29 195 202 10.1149/04529.0195ecst 2016-02-20 OPUS4-30548 Zeitschriftenartikel Markötter, H.; Haußmann, J.; Alink, R.; Tötzke, C.; Arlt, Tobias; Klages, M.; Riesemeier, Heinrich; Scholta, J.; Gerteisen, D.; Banhart, J.; Manke, I. Influence of cracks in the microporous layer on the water distribution in a PEM fuel cell investigated by synchrotron radiography Water evolution in the gas diffusion layer of a polymer electrolyte membrane fuel cell was visualized in situ by means of synchrotron X-ray radiography. Cracks in the microporous layer were identified as start points of efficient liquid water transfer paths through the gas diffusion layer. Quantitative analysis of the water flow rate through those arbitrarily distributed cracks into the gas channel revealed that they have a strong influence on the overall liquid water transport. This could find entry into future material design and simulation. Amsterdam Elsevier 2013 Electrochemistry communications 34 22 24 10.1016/j.elecom.2013.04.006 2016-02-20 OPUS4-31972 Beitrag zu einem Tagungsband Lange, Axel; Hentschel, Manfred P.; Kupsch, Andreas; Jaenisch, Gerd-Rüdiger; Kardjilov, N.; Tötzke, C.; Markötter, H.; Hilger, A.; Manke, I. X-ray compton tomography The potentials of incoherent X-ray Scattering (Compton) tomography are investigated. Imaging materials of very different density or atomic number at once is a perpetual challenge for X-ray tomography or radiography, in general. In a basic laboratory set-up for simultaneous perpendicular Compton Scattering and direct beam attenuation tomographic scans are conducted by single channel photon counting. This results in asymmetric distortions of the projection profiles of the scattering CT-data set. ln a first approach corrections of Compton scattering data by taking advantage of rotational symmetry yield tomograms without major geometric artefacts. A cylindrical sample composed of PE, PA, PVC, glass and wood demonstrates similar Compton contrast for all the substances, while the conventional absorption tomogram only reveals the two high order materials. Compärison to neutron tomography reveals astonishing similarities except for the glass component (without hydrogen). Therefore, Compton CT bears the potential to replace neutron tomography, which requires much more efforts. Brno Brno University of Technology 2014 ECNDT 2014 Proceedings 978-80-214-5018-9 ECNDT 2014 - 11th European Conference on Non-Destructive Testing Prague, Czech Republic 06.10.2014 10.10.2014 1 9 2016-02-20 OPUS4-31084 Zeitschriftenartikel Griesche, Axel; Dabah, Eitan; Kardjilov, N.; Hilger, A.; Manke, I.; Kannengießer, Thomas Imaging of hydrogen in steels using neutrons We investigated the hydrogen distribution spatially and temporally in technical iron at room temperature. Samples were charged electrochemically and subsequently analysed by means of neutron radiography and tomography. The radiographic images allowed for a time-resolved analysis of hydrogen fluxes. The three-dimensional distribution of hydrogen measured by neutron tomography delivered valuable information for the damage analysis of hydrogen-induced cracks. For the first time hydrogen concentration gradients inside the material could be detect directly together with the cracks. The neutron radiography and tomography results were gained at the Research Reactor BER II of the HZB in Berlin. München Carl Hanser Deutsche Gesellschaft für Materialkunde 2014 International journal of materials research 105 7 640 644 10.3139/146.111043 2016-02-20 OPUS4-31068 Zeitschriftenartikel Griesche, Axel; Dabah, Eitan; Kannengießer, Thomas; Kardjilov, N.; Hilger, A.; Manke, I. Three-dimensional imaging of hydrogen blister in iron with neutron tomography We investigated hydrogen embrittlement and blistering in electrochemically hydrogen-charged technical iron samples at room temperature. Hydrogen-stimulated cracks and blisters and the corresponding hydrogen distributions were observed by neutron tomography. Cold neutrons were provided by the research reactor BER II to picture the sample with a spatial resolution in the reconstructed three-dimensional model of ~25 µm. We made the unique observation that cracks were filled with molecular hydrogen and that cracks were surrounded by a 50 µm wide zone with a high hydrogen concentration. The zone contains up to ten times more hydrogen than the bulk material. The hydrogen enriched zone can be ascribed to a region of increased local defect density. Hydrogen also accumulated at the sample surface having the highest concentration at blistered areas. The surfaces of the brittle fractured cracks showed micropores visualized by scanning electron microscopy. The micropores were located at grain boundaries and were surrounded by stress fields detected by electron backscattered diffraction. The cracks clearly originated from the micropores. Kidlington Elsevier Science 2014 Acta materialia 78 14 22 10.1016/j.actamat.2014.06.034 2016-02-20 OPUS4-22609 Zeitschriftenartikel Manke, I.; Kardjilov, N.; Schäfer, R.; Hilger, A.; Strobl, M.; Dawson, M.; Grünzweig, C.; Behr, G.; Hentschel, Manfred P.; David, C.; Kupsch, Andreas; Lange, Axel; Banhart, J. Three-dimensional imaging of magnetic domains Magnetic domains have been the subject of much scientific investigation since their theoretical existence was first postulated by P.-E. Weiss over a century ago. Up to now, the three-dimensional (3D) domain structure of bulk magnets has never been observed owing to the lack of appropriate experimental methods. Domain analysis in bulk matter thus remains one of the most challenging tasks in research on magnetic materials. All current domain observation methods are limited to studying surface domains or thin magnetic films. As the properties of magnetic materials are strongly affected by their domain structure, the development of a technique capable of investigating the shape, size and distribution of individual domains in three dimensions is of great importance. Here, we show that the novel technique of Talbot-Lau neutron tomography with inverted geometry enables direct imaging of the 3D network of magnetic domains within the bulk of FeSi crystals. London, UK Nature Publishing Group 2010 Nature communications 1 6 10.1038/ncomms1125 2016-02-19 OPUS4-23962 Zeitschriftenartikel Maier, W.; Arlt, Tobias; Wannek, C.; Manke, I.; Riesemeier, Heinrich; Krüger, P.; Scholta, J.; Lehnert, W.; Banhart, J.; Stolten, D. In-situ synchrotron X-ray radiography on high temperature polymer electrolyte fuel cells In contrast to classical low temperature polymer electrolyte fuel cells (LT-PEFCs), the membrane conductivity in high temperature polymer electrolyte fuel cells (HT-PEFCs) (operating temperature ~ 160 °C) is based on proton transport within phosphorus-oxygen acids at different levels of hydration, orthophosphoric acid (H3PO4) being the simplest example. We present for the first time in-situ synchrotron X-ray radiography measurements applied to a HT-PEFC to gain insight into the local composition of the membrane electrode assembly (MEA) under dynamic operating conditions. Transmission changes during the radiographic measurements exhibit a clear influence of the formation of product water on the membrane composition. Amsterdam Elsevier 2010 Electrochemistry communications 12 10 1436 1438 10.1016/j.elecom.2010.08.002 2016-02-19 OPUS4-23589 Zeitschriftenartikel Lange, Axel; Kupsch, Andreas; Hentschel, Manfred P.; Manke, I.; Kardjilov, N.; Arlt, Tobias; Grothausmann, R. Reconstruction of limited computed tomography data of fuel cell components using direct iterative reconstruction of computed tomography trajectories CT (computed tomography) reconstructions of fuel cell components of a yet unrivaled spatial resolution and quality are presented. This is achieved by application of the novel DIRECTT (Direct Iterative Reconstruction of Computed Tomography Trajectories) algorithm. We focus on two different key issues which essentially rule the fuel cell's durability on different length scales and physical interactions. On the resolution scale of some 100 µm agglomerations of condensed water in flow-field channels are detected by means of quasi-in situ neutron CT (after operation). Five orders of magnitude below nanometer sized Ru catalyst particles on carbon black support are visualized by electron tomography. Both types of experiments are especially adapted to the type of material involved but they are accompanied by severe deviations from ideal CT measuring conditions, as well. In order to overcome the tremendous reconstruction artifacts of standard algorithms, we employ DIRECTT which is described in detail. Comparisons of DIRECTT reconstructions to the conventional filtered back projection, prove the significant improvements in both experimental methods. Amsterdam [u.a.] Elsevier 2011 Journal of power sources 196 12 5293 5298 10.1016/j.jpowsour.2010.10.106 2016-02-19 OPUS4-20577 Zeitschriftenartikel Hartnig, C.; Manke, I.; Schloesser, J.; Krüger, P.; Kuhn, R.; Riesemeier, Heinrich; Wippermann, K.; Banhart, J. High resolution synchrotron X-ray investigation of carbon dioxide evolution in operating direct methanol fuel cells The carbon dioxide evolution and bubble formation in an operating fuel has been studied by means of synchrotron X-ray radiography. Two different observation directions have been chosen: a through-plane insight has been employed to track the formation of bubbles starting at the corner of the lands of the flow field; a depth profile of the carbon dioxide evolution has been derived from cross sectional studies describing an affected area of up to 100 µm. The dynamics of the bubble formation and detachment of the bubbles from the position of formation is strongly correlated with the current density. Cracks and breaks in the catalyst layer which result from the preparation process are visible under operating conditions and a possible swelling of the catalyst layer does not reach a complete vanishing of the cracks. Amsterdam Elsevier 2009 Electrochemistry communications 11 8 1559 1562 10.1016/j.elecom.2009.05.047 2016-02-19 OPUS4-20583 Zeitschriftenartikel Zabler, S.; Rueda, A.; Rack, A.; Riesemeier, Heinrich; Zaslansky, P.; Manke, I.; Garcia-Moreno, F.; Banhart, J. Coarsening of grain-refined semi-solid Al-Ge32 alloy: X-ray microtomography and in situ radiography Kidlington Elsevier Science 2007 Acta materialia 55 15 5045 5055 10.1016/j.actamat.2007.05.028 2016-02-19 OPUS4-23044 Zeitschriftenartikel Krüger, P.; Markötter, H.; Klages, M.; Haußmann, J.; Arlt, Tobias; Riesemeier, Heinrich; Hartnig, C.; Banhart, J.; Manke, I.; Scholta, J. Dreidimensionale Untersuchung der Wasserverteilung in einer Miniatur-PEM-Brennstoffzelle München Hanser Bundesanstalt für Materialforschung und -prüfung 2010 MP materials testing 52 10 712 717 2016-02-19 OPUS4-23045 Zeitschriftenartikel Arlt, Tobias; Manke, I.; Wippermann, K.; Schröder, A.; Mergel, J.; Riesemeier, Heinrich; Banhart, J. Röntgen-Kanten-Tomografie und -Radiografie zur Untersuchung von Alterungseffekten in Brennstoffzellenmaterialien München Hanser Bundesanstalt für Materialforschung und -prüfung 2010 MP materials testing 52 10 692 697 2016-02-19 OPUS4-23046 Zeitschriftenartikel Markötter, H.; Manke, I.; Hartnig, C.; Krüger, P.; Wippermann, K.; Arlt, Tobias; Choinka, G.; Riesemeier, Heinrich; Banhart, J. Hochauflösende Synchrotron-Radiografie München Hanser Bundesanstalt für Materialforschung und -prüfung 2010 MP materials testing 52 10 698 704 2016-02-19 OPUS4-34289 Beitrag zu einem Tagungsband Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Jaenisch, Gerd-Rüdiger; Kardjilov, N.; Tötzke, C.; Markötter, H.; Hilger, A.; Manke, I. Compton-CT als Alternative zur Neutronentomographie? Als Alternative zur Neutronentomographie wird das Potenzial der Computertomographie (CT) mit inkohärenter Röntgen-Streustrahlung (Compton-Streuung) untersucht. Die gleichzeitige Abbildung von Materialien sehr unterschiedlicher Dichten (Ordnungszahlen) ist eine wiederkehrende Herausforderung für die Radiologie und die Computertomographie mit Röntgenstrahlung. Die Messungen ergeben asymmetrische Projektionsprofile für Sinogramme der Streuintensität. Am Beispiel verschiedener Polymere (Polyethylen, Polyamid, PVC), Glas und Holz wird in den Tomogrammen ein hochaufgelöster 'Comptonkontrast' vergleichbarer Dynamik erreicht, während der simultan gemessene 'Absorptionskontrast' ausschließlich die starken Absorber (Glas und PVC) zeigt. Der Vergleich mit ähnlich auflösender Neutronentomographie zeigt ähnliche Kontraste und eröffnet mithin die Möglichkeit, diese künftig durch Compton-Tomographie im Labormaßstab zu ersetzen. Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) 2015 DACH-Jahrestagung 2015 978-3-940283-68-9 DACH-Jahrestagung 2015 Salzburg, Austria 11.05.2015 13.05.2015 DGZfP BB 152 Mo.3.A.2, 1 10 urn:nbn:de:kobv:b43-342894 http://creativecommons.org/licenses/by-nd/3.0/de/ 2016-02-20 OPUS4-33081 Zeitschriftenartikel Tötzke, C.; Manke, I.; Gaiselmann, G.; Bohner, J.; Müller, Bernd R.; Kupsch, Andreas; Hentschel, Manfred P.; Schmidt, V.; Banhart, J.; Lehnert, W. A dedicated compression device for high resolution X-ray tomography of compressed gas diffusion layers We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell. Melville, NY, USA American Institute of Physics 2015 Review of scientific instruments 86 4 043702-1 043702-6 10.1063/1.4918291 2016-02-20 OPUS4-34802 Zeitschriftenartikel Griesche, Axel; Dabah, Eitan; Kannengießer, Thomas; Hilger, A.; Kardjilov, N.; Manke, I.; Schillinger, B. Measuring hydrogen distributions in iron and steel using neutrons Neutron tomography has been applied to investigate the mechanism of hydrogen assisted cracking in technical iron and supermartensitic steel. Rectangular technical iron block samples showed blistering due to intense hydrogen charging and the tomographic method revealed in situ the spatial distribution of hydrogen and cracks. Hydrogen accumulated in a small region around cracks and the cracks are filled with hydrogen gas. Cracks close to the surface contained no hydrogen. Hydrogenous tensile test samples of supermartensitic steel were pulled until rupture and showed hydrogen accumulations at the notch base and in the plastically deformed region around the fracture surface. Amsterdam Elsevier B.V. 2015 Physics Procedia 69 10th World Conference on Neutron Radiography (WCNR) Grindelwald, Switzerland 05.10.2014 10.10.2014 445 450 urn:nbn:de:kobv:b43-348022 10.1016/j.phpro.2015.07.062 http://creativecommons.org/licenses/by-nc-nd/3.0/de/deed.de 2016-02-20 OPUS4-34191 Zeitschriftenartikel Manke, I.; Kardjilov, N.; Schäfer, R.; Hilger, A.; Grothausmann, R.; Strobl, M.; Dawson, M.; Grünzweig, C.; Tötzke, C.; David, C.; Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Banhart, J. Three-dimensional imaging of magnetic domains with neutron grating interferometry This paper gives a brief overview on3D imaging of magnetic domains with shearing grating neutron tomography. We investigated the three-dimensional distribution of magnetic domain walls in the bulk of a wedge-shaped FeSi single crystal. The width of the magnetic domains wasanalyzed at different locations within the crystal. Magnetic domains close to the tip of the wedge are much smaller than in the bulk. Furthermore, the three-dimensional shape of individual domains wasinvestigated. We discuss prospects and limitations of the applied measurement technique. Amsterdam Elsevier B.V. 2015 Physics procedia 69 404 412 urn:nbn:de:kobv:b43-341919 10.1016/j.phpro.2015.07.057 http://creativecommons.org/licenses/by-nc-nd/3.0/de/deed.de 2016-02-20 OPUS4-32410 Zeitschriftenartikel Arlt, Tobias; Klages, M.; Messerschmidt, M.; Riesemeier, Heinrich; Scholta, J.; Banhart, J.; Manke, I. Influence of artificial aging of gas diffusion layers on the water management of PEM fuel cells The influence of artificial aging of gas diffusion layers (GDL) on the water management within the GDL was investigated in-operando by synchrotron X-ray radiography. One GDL was subjected to an accelerated aging procedure in 30% H2O2 solution, while another GDL was pristine. Radiographic measurements were combined with temporally resolved electrical analyzes. Significant differences in cell voltage and water accumulation were observed during cell operation at steady-state conditions. The cell which contained the aged GDL featured a higher water amount especially at the anode side and a lower cell voltage. Pennington, NJ, USA ECS 2014 ECS electrochemistry letters 3 2 F7 F9 10.1149/2.004402eel 2016-02-20 OPUS4-38574 Zeitschriftenartikel Dabah, Eitan; Pfretzschner, Beate; Schaupp, Thomas; Kardjilov, N.; Manke, I.; Boin, M.; Woracek, R.; Griesche, Axel Time-resolved Bragg-edge neutron radiography for observing martensitic phase transformation from austenitized super martensitic steel Neutron Bragg-edge imaging was applied for the visualization of a γ-Austenite to α'-martensite phase transformation. In the present study, a super martensitic stainless steel sample was heated until complete austenitization and was subsequently cooled down to room temperature. The martensitic phase Transformation started at Ms = 190 °C. Using a monochromatic neutron beam with λ = 0.390 nm, the transmitted intensity was significantly reduced during cooling below Ms, since the emerging martensitic phase has a higher attenuation coefficient than the austenitic phase at this wavelength. The phase Transformation process was visualized by filming the transmission images from a scintillator screen with a CCD camera with a temporal resolution of 30 s and a spatial resolution of 100 µm. 2017 Journal of Materials Science 52 6 3490 3496 10.1007/s10853-016-0642-9 2016-12-19 OPUS4-51100 Zeitschriftenartikel Risse, S.; Juhl, A.; Mascotto, S.; Arlt, T.; Markötter, Henning; Hilger, A.; Manke, I.; Fröba, M. Detailed and Direct Observation of Sulfur Crystal Evolution During Operando Analysis of a Li-S Cell with Synchrotron Imaging Herein, we present a detailed investigation of the electrochemically triggered formation and dissolution processes of α- and β-sulfur crystals on a monolithic carbon cathode using operando high-resolution synchrotron radiography (438 nm/pixel). The combination of visual monitoring with the electrical current response during cyclic voltammetry provides valuable insights into the sulfur formation and dissolution mechanism. Our observations show that the crystal growth process is mainly dictated by a rapid equilibrium between long-chain polysulfides on one side and solid sulfur/short-chain polysulfides on the other side, which is consistent with previous studies in this field. The high temporal and spatial resolution of synchrotron imaging enables the observation of different regimes during the sulfur formation and dissolution process. The appearance of short-chain polysulfides after the first anodic CV peak initiates a rapid dissolution process of α-sulfur crystals on the cathode. The increase in the long-chain lithium polysulfide concentration at the cathode surface during charge results in an increased crystal growth rate, which in turn produces imperfections in α- and β-sulfur crystals. There are strong indications that these defects are fluid inclusions, which may trap dissolved polysulfides and therefore reduce the electrochemical cell capacity. 2020 The Journal of Pysical Chemistry Letters 11 14 5674 5679 10.1021/acs.jpclett.0c01284 2020-08-12 OPUS4-35801 Zeitschriftenartikel Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Lück, S.; Schmidt, V.; Grothausmann, R.; Hilger, A.; Manke, I. Missing wedge computed tomography by iterative algorithm DIRECTT A strategy to mitigate typical reconstruction artefacts in missing wedge computed tomography is presented. These artefacts appear as elongations of reconstructed details along the mean direction (i.e. the symmetry centre of the projections). Although absent in standard computed tomography applications, they are most prominent in advanced electron tomography and also in special topics of X-ray and Neutron tomography under restricted geometric boundary conditions. We investigate the Performance of the DIRECTT (Direct Iterative Reconstruction of Computed Tomography Trajectories) algorithm to reduce the directional artefacts in standard procedures. In order to be sensitive to the anisotropic nature of missing wedge artefacts, we investigate isotropic substructures of metal foam as well as circular disc models. Comparison is drawn to filtered backprojection and algebraic techniques. Reference is made to reconstructions of complete data sets. For the purpose of assessing the reconstruction Quality, Fourier transforms are employed to visualize the missing wedge directly. Deficient reconstructions of disc models are evaluated by a length-weighted boundary orientations. The DIRECTT results are assessd at different signal-to-noise ratios by means of local and integral evaluation Parameters. Hoboken, New Jersey, USA Wiley Royal Microscopical Society 2016 Journal of microscopy 261 1 36 45 10.1111/jmi.12313 2016-04-21 OPUS4-34963 Zeitschriftenartikel Kupsch, Andreas; Lange, Axel; Hentschel, Manfred P.; Jaenisch, Gerd-Rüdiger; Kardjilov, N.; Tötzke, C.; Markötter, H.; Hilger, A.; Manke, I. X-ray compton line scan tomography The potentials of incoherent X-ray scattering (Compton) computed tomography (CT) are investigated. The imaging of materials of very different atomic number or density at once is generally a perpetual challenge for X-ray tomography or radiography. In a basic laboratory set-up for simultaneous perpendicular Compton scattering and direct beam attenuation tomography are conducted by single channel photon counting line scans. This results in asymmetric distortions of the projection profiles of the scattering CT data set. In a first approach, corrections of Compton scattering data by taking advantage of rotational symmetry yield tomograms without major geometric artefacts. A cylindrical sample composed of PE, PA, PVC, glass and wood demonstrates similar Compton contrast for all the substances, while the conventional absorption tomogram only reveals the two high order materials. Comparison to neutron tomography reveals astonishing similarities except for the glass component (without hydrogen). Therefore, Compton CT offers the potential to replace neutron tomography, which requires much more efforts. München Hanser 2015 Materials testing 57 11-12 985 991 10.3139/120.110799 2016-02-20 OPUS4-50217 Zeitschriftenartikel Al-Falahat, A.M.; Kupsch, Andreas; Hentschel, M.P.; Lange, A.; Kardjilov, N.; Markötter, Henning; Manke, I. Correction approach of detector backlighting in radiography In various kinds of radiography, deficient transmission imaging may occur due to backlighting inside the detector itself arising from light or radiation scattering. The related intensity mismatches barely disturb the high resolution contrast, but its long range nature results in reduced attenuation levels which are often disregarded. Based on X-ray observations and an empirical formalism, a procedure is developed for a first order correction of detector backlighting. A backlighting factor is modeled as a function of the relative detector coverage by the sample projection. Different cases of sample transmission are regarded at different backlight factors and detector coverage. The additional intensity of backlighting may strongly affect the values of materials' attenuation up to a few 10%. The presented scenario provides a comfortable procedure for corrections of X-ray or neutron transmission imaging data. Melville, NY, USA American Institute of Physics 2019 Review of Scientific Instruments 90 12 125108 10.1063/1.5097170 2020-01-20 OPUS4-51580 Zeitschriftenartikel Ziesche, R.; Robinson, J.; Kok, M.; Markötter, Henning; Kockelmann, W.; Kardjilov, N.; Manke, I.; Brett, D.; Shearing, P. Editors' Choice—4D Neutron and X-ray Tomography Studies of High Energy Density Primary Batteries: Part I. Dynamic Studies of LiSOCl2 during Discharge The understanding of dynamic processes in Li-metal batteries is an important consideration to enable the full capacity of cells to be utilised. These processes, however, are generally not directly observable using X-ray techniques due to the low attenuation of Li; and are challenging to visualise using neutron imaging due to the low temporal resolution of the technique. In this work, complementary X-ray and neutron imaging are combined to track the dynamics of Li within a primary Li/SOCl2 cell. The temporal challenges posed by neutron imaging are overcome using the golden ratio imaging method which enables the identification of Li diffusion in operando. This combination of techniques has enabled an improved understanding of the processes which limit rate performance in Li/SOCl2 cells and may be applied beyond this chemistry to other Li-metal cells. IOP Publishing 2020 Journal of the Electrochemical Society 13 167 130545 urn:nbn:de:kobv:b43-515802 10.1149/1945-7111/abbbbc https://creativecommons.org/licenses/by/4.0/deed.de 2020-11-18 OPUS4-52166 Zeitschriftenartikel Tran, K. V.; Woracek, R.; Kardjilov, N.; Markötter, Henning; Hilger, A.; Kockelmann, W.; Kelleher, J.; Puplampu, S. B.; Penumadu, D.; Tremsin, A. S.; Banhart, J.; Manke, I. Spectral neutron tomography Combined three-dimensional (3D) mapping of (micro-)structures with elemental and crystalline phase variations is of significant importance for the characterization of materials. Neutron wavelength selective imaging is a spectral imaging technique that exploits unique contrast differences e.g. for mapping dissimilar elemental, isotope, or phase compositions, and has the particular advantage of being applicable to sample volumes on the meso- and macroscale. While being mostly applied as radiography (2D) so far, we herein report that the extension to tomography allows for the display of the full spectral information for every voxel and in 3D. The development is supported by example data from a continuous as well as a pulsed neutron source. As a practical example, we collected 4D data sets (3D + spectral) of plastically deformed metastable stainless steel and herein demonstrate an improved quantification strategy for crystalline phase fractions. These exemplary results illustrate that localized phase transformations can be quantified even in complex geometries within centimeter-sized samples, and we will discuss the limits and future prospects of the technique that is not limited to crystalline materials. Elsevier Ltd. 2021 Materials Today Advances 9 132 urn:nbn:de:kobv:b43-521668 10.1016/j.mtadv.2021.100132 https://creativecommons.org/licenses/by/4.0/deed.de 2021-03-01 OPUS4-43356 Zeitschriftenartikel Alrwashdeh, S. S.; Markötter, H.; Haußmann, J.; Hilger, A.; Klages, M.; Müller, Bernd R.; Kupsch, Andreas; Riesemeier, Heinrich; Scholta, J.; Manke, I. Investigation of water transport in newly developed micro porous layers for polymer electrolyte membrane fuel cells In this investigation, synchrotron X-ray imaging was used to investigate the water distribution inside newly developed gas diffusion media in polymer electrolyte membrane fuel cells. In-situ radiography was used to reveal the relationship between the structure of the microporous layer (MPL) and the water flow in a newly developed MPL equipped with randomly arranged holes. A strong influence of these holes on the overall water transport was found. This contribution provides a brief overview to some of our recent activities on this research field. Korean Society of Microscopy 2017 Applied Microscopy 47 3 101 104 10.9729/AM.2017.47.3.101 2017-12-08 OPUS4-46552 Zeitschriftenartikel Göbel, M.; Kirsch, S.; Schwarze, L:; Schmidt, L.; Scholz, H.; Haußmann, J.; Klages, M.; Scholta, J.; Markötter, H.; Alrwashdeh, S.; Manke, I.; Müller, Bernd R. Transient limiting current measurements for characterization of gas diffusion layers The water management in proton exchange membrane fuel cells (PEMFC) is strongly influenced by the design of the gas diffusion layers (GDL). Limiting current measurements in small-scale cells operating at high stoichiometries are useful to determine the oxygen transport resistance. The oxygen transport resistance increases, once water condenses inside the GDL. In this study a new electrochemical method for voltage loss estimation of GDL induced oxygen transport losses are presented. This new method, referred to as "transient limiting current" (TLC), is compared with the literature method. TLC allows a direct estimation of oxygen transport resistance at an arbitrarily conditioned state. This study also presents a case study of liquid water visualization of a PEM fuel cell with varying GDLs types. With the help of quasi in-situ synchrotron X-ray computed tomography and time resolved radiography measurements we investigate appearance and distribution of liquid water inside the GDLs under limiting current conditions. Elsevier B.V. 2018 Journal of Power Sources 402 237 245 10.1016/j.jpowsour.2018.09.003 2018-11-12 OPUS4-46936 Zeitschriftenartikel Arlt, T.; Kardjilov, N.; Kupsch, Andreas; Manke, I.; Salvemini, F.; Grazzi, F. Neutronen-Laminografie am Beispiel eines historischen Artefakts Die Computer-gestützte Laminografie (CL) wurde als komplementäre Methode zur Computertomografie für die dreidimensionale Bildgebung von lateral ausgedehnten Objekten entwickelt. Ursprünglich für medizinische Zwecke verwendet, wurde diese Methode kürzlich als zerstörungsfreie nicht-invasive Methode nicht nur in der Materialforschung, sondern auch mit steigendem Interesse für kunsthandwerkliche und historische Objekte eingesetzt. Hier wird die Computer-gestützten Laminografie mit polychromatischer Neutronenstrahlung an einer historischen Tsuba eingesetzt, einem Stichblatt eines japanischen Schwerts. Eine Analyse der Lötstellen gibt Rückschlüsse auf das Herstellungsverfahren. Zudem wurden unterschiedliche Materialsysteme gefunden, vermutlich um dem Tsuba lokal eine höhere Stabilität zu verleihen. Die Messungen wurden an der Imaging-Beamline CONRAD-2 an der Neutronenquelle BER 2 des Helmholtz-Zentrums Berlins (HZB) durchgeführt. München Carl Hanser Verlag 2018 Materials Testing 60 12 1209 1214 10.3139/120.111261 2018-12-07 OPUS4-58833 Zeitschriftenartikel Yao, J.; Zhu, G.; Dong, K.; Osenberg, M.; Hilger, A.; Markötter, Henning; Ju, J.; Sun, F.; Manke, I.; Cui, G. Progress and Perspective of Controlling Li Dendrites Growth in All-Solid-State Li Metal Batteries via External Physical Fields Li dendrites penetration through solid electrolytes (SEs) challenges the development of solid-state Li batteries (SSLBs). To date, significant efforts are devoted to understand the mechanistic dynamics of Li dendrites nucleation, growth, and propagation in SEs, and various strategies that aim to alleviate and even inhibit Li dendrite formation have been proposed. Nevertheless, most of these conventional strategies require either additional material processing steps or new materials/layers that eventually increase battery cost and complexity. In contrast, using external fields, such as mechanical force, temperature physical field, electric field, pulse current, and even magnetic field to regulate Li dendrites penetration through SEs, seems to be one of the most cost-effective strategies. This review focuses on the current research progress of utilizing external physical fields in regulating Li dendrites growth in SSLBs. For this purpose, the mechanical properties of Li and SEs, as well as the experimental results that visually track Li penetration dynamics, are reviewed. Finally, the review ends with remaining open questions in future studies of Li dendrites growth and penetration in SEs. It is hoped this review can shed some light on understanding the complex Li dendrite issues in SSLBs and potentially guide their rational design for further development. Weinheim Wiley-VCH 2023 Advanced Energy and Sustainability Research 1 44 urn:nbn:de:kobv:b43-588331 10.1002/aesr.202300165 https://creativecommons.org/licenses/by/4.0/deed.de 2023-11-16 OPUS4-56910 Zeitschriftenartikel Tran, K. V.; Woracek, R.; Kardjilov, N.; Markötter, Henning; Abou-Ras, D.; Puplampu, S.; Förster, C.; Penumadu, D.; Dahlberg, C. F. O.; Banhart, J.; Manke, I. Torsion of a rectangular bar: Complex phase distribution in 304L steel revealed by neutron tomography Metastable austenitic stainless steel (304L) samples with a rectangular cross-section were plastically deformed in torsion during which they experienced multiaxial stresses that led to a complex martensitic phase distribution owing to the transformation induced plasticity effect. A three-dimensional characterization of the phase distributions in these cm-sized samples was carried out by wavelength-selective neutron tomography. It was found that quantitatively correct results are obtained as long as the samples do not exhibit any considerable preferential grain orientation. Optical microscopy, electron backscatter diffraction, and finite element modeling were used to verify and explain the results obtained by neutron tomography. Altogether, neutron tomography was shown to extend the range of microstructure characterization methods towards the meso- and macroscale. Elsevier Ltd. 2022 Materials & Design 222 1 13 urn:nbn:de:kobv:b43-569101 10.1016/j.matdes.2022.111037 https://creativecommons.org/licenses/by/4.0/deed.de 2023-01-30 OPUS4-58626 Zeitschriftenartikel Jamro, R.; Mente, Tobias; Kardjilov, N.; Markötter, Henning; Al-Falahat, Ala'A. M.; Woracek, R.; Manke, I.; Griesche, Axel Temperature distribution during welding measured by neutron imaging This study was carried out to investigate the neutron transmission signal as a function of sample temperature during a welding process. A theoretical description that includes the Debye-Waller factor was used to describe the temperature influence on the neutron crosssections. Neutron imaging using a monochromatic beam helps to observe transmission variations related to the material temperature. In-situ neutron imaging of welding experiments show the distribution of the temperature in bulk steel samples. The performed finite element modelling of expected temperature distributions shows good agreement with the obtained experimental data. IOP Publishing Ltd. 2023 Journal of Physics: Conference Series 2605 1 10 urn:nbn:de:kobv:b43-586268 10.1088/1742-6596/2605/1/012026 https://creativecommons.org/licenses/by/4.0/deed.de 2023-10-23 OPUS4-57309 Zeitschriftenartikel Zheng, Y.; Zhang, S.; Ma, J.; Sun, F.; Osenberg, M.; Hilger, A.; Markötter, Henning; Wilde, F.; Manke, I.; Hu, Z.; Cui, G. Codependent failure mechanisms between cathode and anode in solid state lithium metal batteries: mediated by uneven ion flux An in-depth understanding of the degradation mechanisms is a prerequisite for developing the nextgeneration all solid-state lithium metal battery (ASSLMB) technology. Herein, synchrotron X-ray computed tomography (SXCT) together with other probing tools and simulation method were employed to rediscover the decaying mechanisms of LiNi0.8Co0.1Mn0.1O2 (NCM)|Li6PS5Cl (LPSCl)|Li ASSLMB. It reveals that the detachment and isolation of NCM particles cause the current focusing on the remaining active regions of cathode. The extent of Li stripping and the likelihood of Li+ plating into LPSCl facing the active NCM particles becomes higher. Besides, the homogeneity of Li stripping/plating is improved by homogenizing the electrochemical reactions at the cathode side by LiZr2(PO4)3 (LZP) coating. These results suggest a codependent failure mechanism between cathode and anode that is mediated by uneven Li ion flux. This work contributes to establish a holistic understanding of the degradation mechanisms in ASSLMBs and opens new opportunities for their further optimization and evelopment. Elsevier B.V. 2023 Science Bulletin 68 8 813 825 10.1016/j.scib.2023.03.021 2023-04-17 OPUS4-55027 Zeitschriftenartikel Hoffmann, H; Paulisch, M C; Gebhard, M; Osiewacz, J; Kutter, M; Hilger, A; Arlt, T; Kardjilov, N; Ellendorff, B; Beckmann, F; Markötter, Henning; Luik, M; Turek, T; Manke, I; Roth, C Development of a Modular Operando Cell for X-ray Imaging of Strongly Absorbing Silver-Based Gas Diffusion Electrodes Metal-based gas diffusion electrodes are utilized in chlor-alkali electrolysis or electrochemical reduction of carbon dioxide, allowing the reaction to proceed at high current densities. In contrast to planar electrodes and predominantly 2D designs, the industrially required high current densities can be achieved by intense contact between the gas and liquid phase with the catalytically active surfaces. An essential asset for the knowledge-based design of tailored electrodes is therefore in-depth information on electrolyte distribution and intrusion into the electrode's porous structure. Lab-based and synchrotron radiography allow for monitoring this process operando. Herein, we describe the development of a cell design that can be modularly adapted and successfully used to monitor both the oxygen reduction reaction and the electrochemical reduction of CO2 as exemplary and currently very relevant examples of gas-liquid reactions by only minor modifications to the cell set-up. With the reported cell design, we were able to observe the electrolyte distribution within the gas diffusion electrode during cell operation in realistic conditions. IOP science 2022 Journal of The Electrochemical Society 169 4 044508 10.1149/1945-7111/ac6220 2022-06-15 OPUS4-53419 Zeitschriftenartikel Kardjilov, N; Manke, I; Hilger, A; Arlt, T; Bradbury, R; Markötter, Henning; Woracek, R; Strobel, M; Treimer, W; Banhart, J The Neutron Imaging Instrument CONRAD — Post-Operational Review The neutron imaging instrument CONRAD was operated as a part of the user program of the research reactor BER-II at Helmholtz-Zentrum Berlin (HZB) from 2005 to 2020. The Instrument was designed to use the neutron flux from the cold source of the reactor, transported by a curved neutron guide. The pure cold neutron spectrum provided a great advantage in the use of different neutron optical components such as focusing lenses and guides, solid-state polarizers, Monochromators and phase gratings. The flexible setup of the instrument allowed for implementation of new methods including wavelength-selective, dark-field, phase-contrast and imaging with polarized neutrons. In summary, these developments helped to attract a large number of scientists and industrial customers, who were introduced to neutron imaging and subsequently contributed to the Expansion of the neutron imaging community. MDPI 2021 Journal of imaging 7 11 7010011 urn:nbn:de:kobv:b43-534190 10.3390/ jimaging7010011 https://creativecommons.org/licenses/by/4.0/deed.de 2021-09-29 OPUS4-53394 Zeitschriftenartikel Tang, F; Wu, Z; Yang, C; Osenberg, M; Hilger, A; Dong, K; Markötter, Henning; Manke, I; Sun, F; Chen, L; Cui, G Synchrotron X-ray tomography for rechargeable battery research: Fundamentals, setups and applications Understanding the complicated interplay of the continuously evolving electrode materials in their inherent 3D states during the battery operating condition is of great importance for advancing rechargeable battery research. In this regard, the synchrotron X-ray tomography technique, which enables non-destructive, multi-scale, and 3D imaging of a variety of electrode components before/during/after battery operation, becomes an essential tool to deepen this understanding. The past few years have witnessed an increasingly growing interest in applying this technique in battery research. Hence, it is time to not only summarize the already obtained battery-related Knowledge by using this technique, but also to present a fundamental elucidation of this technique to boost future studies in battery research. To this end, this review firstly introduces the fundamental principles and experimental Setups of the synchrotron X-ray tomography technique. After that, a user guide to ist application in battery research and examples of its applications in Research of various types of batteries are presented. The current review ends with a discussion of the future opportunities of this technique for next-generation rechargeable batteries research. It is expected that this review can enhance the reader's understanding of the synchrotron X-ray tomography technique and stimulate new ideas and opportunities in battery research. Wiley-VCH 2021 Small Methods 5 9 2100557 10.1002/smtd.202100557 2021-09-29 OPUS4-55689 Zeitschriftenartikel Al-Falahat, A M; Kardjilov, N; Woracek, R; Boin, M; Markötter, Henning; Kuhn, L T; Makowska, M; Strobl, M; Pfretzschner, B; Banhart, J; Manke, I Temperature dependence in Bragg edge neutron transmission measurements A systematic study has been carried out to investigate the neutron transmission signal as a function of sample temperature. In particular, the experimentally determined wavelength-dependent neutron attenuation spectra for a martensitic steel at temperatures ranging from 21 to 700°C are compared with simulated data. A theoretical description that includes the Debye-Waller factor in order to describe the temperature influence on the neutron cross sections was implemented in the nxsPlotter software and used for the simulations. The analysis of the attenuation coefficients at varying temperatures shows that the missing contributions due to elastic and inelastic scattering can be clearly distinguished: while the elastically scattered intensities decrease with higher temperatures, the inelastically scattered intensities increase, and the two can be separated from each other by analysing unique sharp features in the form of Bragg edges. This study presents the first systematic approach to quantify this effect and can serve as a basis , for example, to correct measurements taken during in situ heat treatments, in many cases being a prerequisite for obtaining quantifiable results. International Union of Crystallography 2022 Journal of Applied Crystallography 55 Pt 4 919 928 urn:nbn:de:kobv:b43-556896 10.1107/S1600576722006549 https://creativecommons.org/licenses/by/4.0/deed.de 2022-09-14 OPUS4-52402 Zeitschriftenartikel Mohseninia, A; Eppler, M; Kartouzian, D; Markötter, Henning; Kardjilov, N; Wilhelm, F; Scholta, J; Manke, I PTFE Content in Catalyst Layers and Microporous Layers: Effect on Performance and Water Distribution in Polymer Electrolyte Membrane Fuel Cells This work describes the effects of catalyst layers (CLs) consisting of hydrophobic PTFE on the performance and water management of PEM fuel cells. Catalyst inks with various PTFE contents were coated on Nafion membranes and characterized using contact angle measurements, SEX-EDX, and mercury porosimetry. Fuel cell tests and electrochemical impedance spectroscopy (EIS) were conducted under varying operating conditions for the prepared materials. At dry conditions, CLs with 5 wt.% PTFE were advantageous for cell performance due to improved membrane hydration, whereas under humid conditions and high air flow rates CLs with 10 wt.% PTFE improved the performance in high current density region. Higher PTFE contents (⩾20 wt.%) increased the mass transport resistance due to reduced porosity of the CLs structure. Operando neutron radiography was utilized to study the effects of hydrophobicity gradients within CLs and cathode microporous layer (MPLC) on liquid water distribution. More hydrophobic CLs increased the water content in adjacent layers and improved performance, especially at dry conditions. MPLC with higher PTFE contents increased the overall liquid water within the CLs and GDLs and escalated the water transfer to the anode side. Furthermore, the role of back-diffusion transport mechanism on water distribution was identified for the investigated cells. IOP Science 2021 Journal of the Electrochemical Society 168 3 034509 10.1149/1945-7111/abec53 2021-04-08