TY - CONF A1 - Cakir, Cafer Tufan T1 - Scanning-Free Grazing Exit XANES Analysis of Stratified Samples and the Optimization of the Data Collection Process N2 - The components that are used in structural and in high temperature applications generally face significant challenges with respect to oxidation behaviours and metalworking processes. In most of the cases, harsh environmental conditions lead materials to degrade due to corrosion. To thoroughly investigate the corrosion processes and to determine oxidation states of metal components within the reaction products, we need special analytical tools. Grazing exit X-ray fluorescence (GEXRF) offers a non-destructive way to collect this information in sub-micrometre depth range. In order to obtain structural information, such as regarding oxidation states or atomic/molecular geometric arrangement, the GEXRF approach can also be combined with the X-ray absorption spectroscopy (XAS) method. The position and energy sensitive detector, with 264x264 pixel detector area, provides information regarding the signal emitted from the sample as a function of the emission angle and thus allows depth-sensitive analysis. Furthermore, the data collected from samples of an incidence energy which can be controlled with a resolution of 0.5 eV provides XANES data to determine oxidation states. We address the feasibility of our setup and provide a new optimization procedure (Bayesian Optimization and Gaussian Regression) to decrease measuring time. The results settle on a conceptual study on a reference sample (Cr-Oxide layer (300nm) on Cr layer (500nm) on Si wafer). T2 - Denver X-Ray Conference DXC 2022 CY - Washington D.C., USA DA - 07.08.2022 KW - GEXRF KW - High entropy alloys KW - High entropy materials KW - Optimization KW - XANES KW - Grazing exit KW - XAS PY - 2022 AN - OPUS4-56271 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - C. Pardo Pérez, L. A1 - Arndt, A. A1 - Stojkovikj, S. A1 - Y. Ahmet, I. A1 - T. Arens,, J. A1 - Dattila, F. A1 - Wendt, R. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Davies, V. A1 - Höflich, K. A1 - Köhnen, E. A1 - Tockhorn, P. A1 - Golnak, R. A1 - Xiao, J. A1 - Schuck, G. A1 - Wollgarten, M. A1 - López, N. A1 - T. Mayer, M. T1 - Determining Structure-Activity Relationships in Oxide Derived CuSn Catalysts During CO2 Electroreduction Using X-Ray Spectroscopy N2 - The development of earth-abundant catalysts for selective electrochemical CO2 conversion is a central challenge. Cu-Sn bimetallic catalysts can yield selective CO2 reduction toward either CO or formate. This study presents oxide-derived Cu-Sn catalysts tunable for either product and seeks to understand the synergetic effects between Cu and Sn causing these selectivity trends. The materials undergo significant transformations under CO2 reduction conditions, and their dynamic bulk and surface structures are revealed by correlating observations from multiple methods—X-ray absorption spectroscopy for in situ study, and quasi in situ X-ray photoelectron spectroscopy for surface sensitivity. For both types of catalysts, Cu transforms to metallic Cu0 under reaction conditions. However, the Sn speciation and content differ significantly between the catalyst types: the CO-selective catalysts exhibit a surface Sn content of 13 at. % predominantly present as oxidized Sn, while the formate-selective catalysts display an Sn content of ≈70 at. % consisting of both metallic Sn0 and Sn oxide species. Density functional theory simulations suggest that Snδ+ sites weaken CO adsorption, thereby enhancing CO selectivity, while Sn0 sites hinder H adsorption and promote formate production. This study reveals the complex dependence of catalyst structure, composition, and speciation with electrochemical bias in bimetallic Cu catalysts. KW - Electrochemical CO2 conversion KW - Cu catalysts KW - X-ray absorption spectroscopy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547116 DO - https://doi.org/10.1002/aenm.202103328 SN - 1614-6832 VL - 12 IS - 5 SP - 2103328 PB - Wiley-VCH GmbH AN - OPUS4-54711 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bügel, Stefanie A1 - Hähnel, Malte A1 - Kunde, Tom A1 - de Sousa Amadeu, Nader A1 - Sun, Yangyang A1 - Spieß, Alex A1 - Beglau, Thi Hai Yen A1 - Schmidt, Bernd M. A1 - Janiak, Christoph T1 - Synthesis and Characterization of a Crystalline Imine-Based Covalent Organic Framework with Triazine Node and Biphenyl Linker and Its Fluorinated Derivate for CO2/CH4 Separation N2 - : A catalyst-free Schiff base reaction was applied to synthesize two imine-linked covalent organic frameworks (COFs). The condensation reaction of 1,3,5-tris-(4-aminophenyl)triazine (TAPT) with 4,40-biphenyldicarboxaldehyde led to the structure of HHU-COF-1 (HHU = Heinrich-Heine University). The fluorinated analog HHU-COF-2 was obtained with 2,20,3,30,5,50,6,60-octafluoro 4,40 -biphenyldicarboxaldehyde. Solid-state NMR, infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis confirmed the successful formation of the two network structures. The crystalline materials are characterized by high Brunauer–Emmett–Teller surface areas of 2352 m2/g for HHU-COF-1 and 1356 m2/g for HHU-COF-2. The products of a larger-scale synthesis were applied to prepare mixed-matrix membranes (MMMs) with the polymer Matrimid. CO2/CH4 permeation tests revealed a moderate increase in CO2 permeability at constant selectivity for HHU-COF-1 as a dispersed phase, whereas application of the fluorinated COF led to a CO2/CH4 selectivity increase from 42 for the pure Matrimid membrane to 51 for 8 wt% of HHU-COF-2 and a permeability increase from 6.8 to 13.0 Barrer for the 24 wt% MMM KW - Separation KW - COF KW - MMM KW - CO2 PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618625 DO - https://doi.org/10.3390/ma15082807 VL - 15 IS - 8 SP - 2807 PB - MDPI AN - OPUS4-61862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böttcher, Katrin A1 - Schmitt Rahner, M. A1 - Stolzenberg, U. A1 - Kraft, Sebastian A1 - Bonse, Jörn A1 - Feist, C. A1 - Albrecht, D. A1 - Pullner, B. A1 - Krüger, Jörg T1 - Worst-case X-ray photon energies in ultrashort pulse laser processing N2 - Ultrashort pulse laser processing can result in the secondary generation of unwanted X-rays if a critical laser irradiance of about 10^13 W/cm^2 is exceeded. Spectral X-ray emissions were investigated during the processing of tungsten and steel using three complementary spectrometers (based on CdTe and silicon drift detectors) simultaneously for the identification of a worst-case spectral scenario. Therefore, maximum X-ray photon energies were determined, and corresponding dose equivalent rates were calculated. An ultrashort pulse laser workstation with a pulse duration of 274 fs, a center wavelength of 1030 nm, pulse repetition rates between 50 kHz and 200 kHz, and a Gaussian laser beam focused to a spot diameter of 33 µm was employed in a single pulse and burst laser operation mode. Different combinations of laser pulse energy and repetition rate were utilized, keeping the average laser power constant close to the maximum power of 20 W. Peak irradiances ranging from 7.3 × 10^13 W/cm^2 up to 3.0 × 10^14 W/cm^2 were used. The X-ray dose equivalent rate increases for lower repetition rates and higher pulse energy if a constant average power is used. Laser processing with burst mode significantly increases the dose rates and the X-ray photon energies. A maximum X-ray photon energy of about 40 keV was observed for burst mode processing of tungsten with a repetition rate of 50 kHz and a peak irradiance of 3 × 10^14 W/cm^2. KW - Ultrashort pulsed laser KW - X-ray emission KW - X-ray spectrum KW - X-ray energies KW - Radiation protection PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-566176 DO - https://doi.org/10.3390/ma15248996 VL - 15 IS - 24 SP - 1 EP - 17 PB - MDPI AN - OPUS4-56617 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böttcher, Katrin A1 - Kraft, Sebastian A1 - Weise, Matthias A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - X-ray emission during ultrafast laser grooving N2 - Ultrashort pulse lasers offer the possibility to process materials with minimal heat input and high precision. However, the X-ray emission at high laser peak intensities represents an undesirable side effect. A laser system (1030 nm wavelength, 40 W maximum average laser power, 925 fs pulse duration, 100 μJ maximum pulse energy, 400 kHz pulse repetition frequency) was used to analyze the X-ray skin dose rates for applied peak intensities between 9.2 × 10^12 W/cm^2 and 1.3 × 10^14 W/cm^2 for mild steel, stainless steel and tungsten during groove processing. The lowest laser peak intensity at which X-ray emission could be measured was 9.2 × 10^12 W/cm^2 for processing of stainless steel. The X-ray emission showed a characteristic evolution in dependence on the number of overscans at the same line positions. For low peak intensities, a measurable X-ray emission only begins after a few passes. The number of scans to reach the maximum dose rate increases with lower laser peak intensity. Analysis of the evolving surface topography by white light interference microscopy in connection with ray-tracing simulations led to the interpretation that the increase in X-ray emission is due to the local intensity redistribution by multiple reflection within the laser-generated grooves which is promoted by a particular choice of the linear laser polarization. KW - Ultrashort pulsed laser KW - Laser-induced X-rays KW - X-ray hazard KW - X-ray emission PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639483 DO - https://doi.org/10.1007/s00339-025-08728-z SN - 1432-0630 VL - 131 IS - 8 SP - 1 EP - 12 PB - Springer CY - Berlin AN - OPUS4-63948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Béalu, Zoé A1 - Walther, Johanna A1 - Abusafia, Attaallah A1 - Altmann, Korinna A1 - Meurer, Maren A1 - Gretzschel, Oliver A1 - Schäfer, Michael A1 - Steinmetz, Heidrun T1 - Removal of Organic Micropollutants and Microplastics via Ozonation Followed by Granular Activated Carbon Filtration N2 - Discharge from Wastewater Treatment Plants (WWTPs) can result in the emission of organic micropollutants (OMPs) and microplastics (MPs) into the aquatic environment. To prevent this harmful release, a pilot plant consisting of an ozonation followed by a granular activated carbon (GAC) filter was operated at a WWTP in Germany, and its side-effects on the concentrations of nitrogen (N) and phosphorous (P) compounds were measured. Over 80% of OMPs and transformation products were removed during the operating time (around 6000 bed volumes) no matter the ozone dose (from around 0.1 to 0.5 mgO3/mgDOC), except for Diatrizoic acid, whose breakthrough appeared at 3500 BV. Formation of the oxidation by-product, NDMA, increased with higher ozone doses, but the concentration remained below 100 ng/L. Bromate was formed at a higher ozone dose (0.4 mgO3/mgDOC) but at a low concentration—below 10 µg/L. The MP particles detected in the inflow (PE, SBR, PP, and PS) were effectively eliminated to a high degree, with a removal rate of at least 92%. Carbon parameters (COD, DOC, and SAC254) were removed further by the pilot plant, but to different extents. As expected, nitrate was formed during ozonation, while nitrite’s concentration decreased. Further, nitrite decreased and nitrate increased within the GAC filter, while ammonium was eliminated by at least 90%. Total P concentration decreased after the pilot, but the concentration of PO4-P increased. KW - Microplastics KW - TED-GC/MS KW - Granular Activated Carbon Filtration KW - Removal of Organic Micropollutants KW - Wastewater treatment plant PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615209 DO - https://doi.org/10.3390/environments11110241 VL - 11 IS - 11 SP - 1 EP - 38 PB - MDPI AG AN - OPUS4-61520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bäßler, Ralph A1 - Amela Keserović, Amela A1 - Sobetzki, Joana A1 - Sarmiento Klapper, Helmuth A1 - Dimper, Matthias T1 - Geeignete Werkstoffe für Geothermieanwendungen (2) N2 - Durch Auslagerungs- und elektrochemische Tests im Labor kann das Korrosionsverhalten verschiedener metallener Werkstoffe beurteilt werden. Aus den Versuchsergebnissen, die in verschiedenen synthetischen Geothermalwässern im Labor erzielt wurden, lassen sich die folgenden Schlussfolgerungen ziehen: • Die Anfälligkeit für Spaltkorrosion wurde als wichtigster Aspekt für die Werkstoffqualifizierung ermittelt. • Der niedriglegierte Stahl 25CrMo4 zeigte bei niedrigem Salzgehalt in MB-Geothermalwasser eine gleichmäßige Korrosion unterhalb der akzeptierten Schwelle von 0,3 mm/Jahr. Daher kann er als geeignet für geothermische Bedingungen mit niedrigem Salzgehalt angesehen werden, wie sie für MB getestet wurden. Es besteht keine Notwendigkeit, auf höherlegierte (teurere) Werkstoffe auszuweichen. Ein niedrigerer pH-Wert (wie bei LHD) führt zu Korrosionsraten oberhalb der akzeptablen Grenzwerte, so dass die niedriglegierten Werkstoffe nicht für Flüssigkeiten mit niedrigem pH-Wert geeignet sind. • Stark salzhaltige Geothermalwässer erfordern höherlegierte Werkstoffe, da die Korrosionsrate von niedriglegiertem Stahl zu hoch ist. • Der Duplexstahl X2CrNiMo22-5-3 und der Superduplexstahl X2CrNiMoCuWN25-7-4 wurden aufgrund ihrer kritischen Anfälligkeit für örtliche Korrosion in Form von Loch- und Spaltkorrosion unter Betriebsbedingungen nicht als geeignet für geothermische Anwendungen in Geothermalwässern mit einer mit NDB und ORG vergleichbaren Zusammensetzung angesehen. • Der superaustenitische Stahl X1CrNiMoCu32-28-7 eignet sich für ORG und salzarme Wässer. In NDB-Geothermalwasser wurde er bei 100 °C als geeignet angesehen. Jedoch schränkt seine Anfälligkeit für Spaltkorrosion seine Anwendbarkeit ein. Neben seiner guten Korrosionsbeständigkeit ist sein Repassivierungsverhalten für seine begrenzte Anwendbarkeit in Geothermalwässern mit niedrigem pH-Wert verantwortlich. • Die Nickelbasislegierung NiCr23Mo16Al wurde als geeignet erachtet und stellt eine sichere Option für den Einsatz in geothermischen Anlagen dar, selbst wenn mit stark salzhaltigem Geothermalwasser gearbeitet wird. KW - Geothermie KW - Korrosion KW - Legierungen KW - Anlagensicherheit PY - 2024 SN - 0016-4232 VL - 2024 IS - 3 SP - 370 EP - 374 PB - Eugen G. Leuze Verlag CY - Bad Saulgau AN - OPUS4-59997 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bäßler, Ralph A1 - Amela Keserović, Amela A1 - Sobetzki, Joana A1 - Sarmiento Klapper, Helmuth A1 - Dimper, Matthias T1 - Geeignete Werkstoffe für Geothermieanwendungen (1) N2 - Durch Auslagerungs- und elektrochemische Tests im Labor kann das Korrosionsverhalten verschiedener metallener Werkstoffe beurteilt werden. Aus den Versuchsergebnissen, die in verschiedenen synthetischen Geothermalwässern im Labor erzielt wurden, lassen sich die folgenden Schlussfolgerungen ziehen: • Die Anfälligkeit für Spaltkorrosion wurde als wichtigster Aspekt für die Werkstoffqualifizierung ermittelt. • Der niedriglegierte Stahl 25CrMo4 zeigte bei niedrigem Salzgehalt in MB-Geothermalwasser eine gleichmäßige Korrosion unterhalb der akzeptierten Schwelle von 0,3 mm/Jahr. Daher kann er als geeignet für geothermische Bedingungen mit niedrigem Salzgehalt angesehen werden, wie sie für MB getestet wurden. Es besteht keine Notwendigkeit, auf höherlegierte (teurere) Werkstoffe auszuweichen. Ein niedrigerer pH-Wert (wie bei LHD) führt zu Korrosionsraten oberhalb der akzeptablen Grenzwerte, so dass die niedriglegierten Werkstoffe nicht für Flüssigkeiten mit niedrigem pH-Wert geeignet sind. • Stark salzhaltige Geothermalwässer erfordern höherlegierte Werkstoffe, da die Korrosionsrate von niedriglegiertem Stahl zu hoch ist. • Der Duplexstahl X2CrNiMo22-5-3 und der Superduplexstahl X2CrNiMoCuWN25-7-4 wurden aufgrund ihrer kritischen Anfälligkeit für örtliche Korrosion in Form von Loch- und Spaltkorrosion unter Betriebsbedingungen nicht als geeignet für geothermische Anwendungen in Geothermalwässern mit einer mit NDB und ORG vergleichbaren Zusammensetzung angesehen. • Der superaustenitische Stahl X1CrNiMoCu32-28-7 eignet sich für ORG und salzarme Wässer. In NDB-Geothermalwasser wurde er bei 100 °C als geeignet angesehen. Jedoch schränkt seine Anfälligkeit für Spaltkorrosion seine Anwendbarkeit ein. Neben seiner guten Korrosionsbeständigkeit ist sein Repassivierungsverhalten für seine begrenzte Anwendbarkeit in Geothermalwässern mit niedrigem pH-Wert verantwortlich. • Die Nickelbasislegierung NiCr23Mo16Al wurde als geeignet erachtet und stellt eine sichere Option für den Einsatz in geothermischen Anlagen dar, selbst wenn mit stark salzhaltigem Geothermalwasser gearbeitet wird. KW - Geothermie KW - Korrosion KW - Legierungen KW - Anlagensicherheit PY - 2024 SN - 0016-4232 VL - 2024 IS - 2 SP - 240 EP - 243 PB - Eugen G. Leuze Verlag CY - Bad Saulgau AN - OPUS4-59996 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph T1 - Wechselwirkungen in Geothermieanlagen - nicht nur ein Beständigkeitsaspekt N2 - Um Konstrukteuren und Nutzern geothermischer Anlagen grundlegende Informationen über die Korrosionsbeständigkeit zur Verfügung zu stellen, wurden verschiedene metallische Werkstoffe, darunter nichtrostende Duplex- und austenitische Stähle sowie eine Nickellegierung, in künstlichen Geothermalwässern bewertet, die die Bedingungen an verschiedenen Standorten mit geothermischem Potenzial simulieren. Mit Hilfe von elektrochemischen und Langzeittests wurde die Eignung verschiedener metallener Werkstoffe mittels kritischer Potentiale und Korrosionsraten untersucht. In hochsalinaren Umgebungen erwies sich Spaltkorrosion als der entscheidende Mechanismus. Die Nickelbasislegierung zeigt eine ausgezeichnete Beständigkeit gegenüber Lochkorrosion. Abgesehen von ihren hohen Kosten eignet sie sich sehr gut für den Bau von Geothermieanlagen mit stark salzhaltigen Fluiden. Rostfreie Stähle und Duplexstähle weisen eine begrenzte Korrosionsbeständigkeit gegen Loch- und Spaltkorrosion auf. Daher sind sie für stark salzhaltige Fluide nicht geeignet. Der Superaustenit zeigt ein temperaturabhängiges Verhalten. In nichtsalinaren Umgebungen könnten niedrig legierte Stähle (neben den höher legierten Werkstoffen) als Konstruktionsmaterial für Geothermieanlagen eingesetzt werden, sofern eine ausreichende Wandstärke des Materials berücksichtigt wird. Neben Korrosionsaspekten erwies sich auch die Ausfällung von Fluidbestandteilen als interessantes Thema. Beim Betrieb der Forschungsanlage in Groß Schönebeck wurden Kupfer- und Bleieffekte im Bohrloch festgestellt. Die auftretenden Mechanismen und Maßnahmen zur Verhinderung von Ausfällungen und Abscheidungen wurden ebenso untersucht, wie deren mögliche Einflüsse auf die Korrosionsbeständigkeit metallener Werkstoffe für Anlagenkomponenten. Der Vortrag beschreibt die Wechselwirkungen zwischen Geothermalwässern und Ausrüstungs-komponenten. T2 - Geothermiekongress 2024 CY - Potsdam, Germany DA - 22.10.2024 KW - Örtliche Korrosion KW - Edelstahl KW - Geothermie KW - Ni-Legierung KW - Abscheidung PY - 2024 AN - OPUS4-61441 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph T1 - Materials interactions in geothermal plants – not just an aspect of durability N2 - High alloyed corrosion resistant alloys are suitable for high saline geothermal fluids and do not cause copper or lead deposition. They shall be chosen for future design of the piping system, either in massive or in cladded form, if crevices formation with non-metallic materials can be prevented! Otherwise Ni-based alloys or Ti shall be selected. T2 - IFPEN Webinar "Corrosion in geothermal energy production" CY - Online meeting DA - 26.06.2025 KW - Corrosion KW - Geothermal KW - Electrochemistry PY - 2025 AN - OPUS4-63528 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph T1 - Metallene Werkstoffe in Geothermieanlagen - nicht nur aus Sicht der Korrosion N2 - Um Konstrukteuren und Nutzern geothermischer Anlagen grundlegende Informationen über die Korrosionsbeständigkeit zur Verfügung zu stellen, wurden verschiedene metallene Werkstoffe, darunter nichtrostende Duplex- und austenitische Stähle sowie eine Nickellegierung, in künstlichen Geothermalwässern, die die Bedingungen an verschiedenen Standorten mit geothermischem Potenzial simulieren, mit Hilfe von elektrochemischen und Langzeittests hinsichtlich ihrer Eignung bewertet. In hochsalinaren Umgebungen erwies sich Spaltkorrosion als der entscheidende Mechanismus. Die Nickellegierung zeigt eine ausgezeichnete Beständigkeit gegenüber Lochkorrosion. Abgesehen von ihren hohen Kosten eignet sie sich sehr gut für den Bau von Geothermieanlagen mit stark salzhaltigen Fluiden. Rostfreie Stähle und Duplexstähle weisen eine begrenzte Korrosionsbeständigkeit gegen Loch- und Spaltkorrosion auf. Daher sind sie für stark salzhaltige Fluide nicht geeignet. Der Superaustenit zeigt ein temperaturabhängiges Verhalten. In nichtsalinaren Umgebungen könnten niedriglegierte Stähle (neben den höherlegierten Werkstoffen) als Konstruktionsmaterial für Geothermieanlagen eingesetzt werden, sofern eine ausreichende Wandstärke des Materials berücksichtigt wird. Neben Korrosionsaspekten erwies sich auch die Ausfällung von Fluidbestandteilen als interessantes Thema. Beim Betrieb der Forschungsanlage in Groß Schönebeck wurden Kupfer- und Bleieffekte im Bohrloch festgestellt. Die auftretenden Mechanismen und Maßnahmen zur Verhinderung von Ausfällungen und Abscheidungen wurden ebenso untersucht, wie deren mögliche Einflüsse auf die Korrosionsbeständigkeit metallener Werkstoffe für Anlagenkomponenten. Der Beitrag beschreibt die Wechselwirkungen zwischen Geothermalwässern und Ausrüstungskomponenten. T2 - 57. Kraftwerktechnisches Kolloquium CY - Dresden, Germany DA - 07.10.2025 KW - Örtliche Korrosion KW - Edelstahl KW - Ni-Legierungen KW - Geothermie KW - Abscheidung PY - 2025 AN - OPUS4-64323 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bäßler, Ralph T1 - Metallic Materials for Geothermal Applications N2 - The aim of the work presented was the evaluation of corrosion resistance of various materials in geothermal Waters as a base to create a catalogue of suitable materials for applications in (not only) German geothermal power plants. Users shall be enabled to have a basis for designing such facilities. High alloyed corrosion resistant alloys are suitable and do not cause copper or lead deposition. They shall be chosen for future design of the piping system, either in massive or in cladded form, if crevices formation with non-metallic materials can be prevented! T2 - IFPEN-Workshop: Corrosion in Low-Carbon Energies CY - Online meeting DA - 03.11.2020 KW - Geothermal KW - Corrosion KW - Saline brine PY - 2020 AN - OPUS4-51511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bustos, Jenna A1 - Shohel, Mohammad A1 - Guilherme Buzanich, Ana A1 - Zakharov, Lev A1 - Buils, Jordi A1 - Segado‐Centellas, Mireia A1 - Bo, Carles A1 - Nyman, May T1 - Technetium and Rhenium Auto‐reduction, Polymerization and Lability towards Group VII Polyoxometalate Chemistry N2 - AbstractGroup VII Tc and Re have long been studied to develop both radiopharmaceuticals and technologies for nuclear materials management. Fundamental research has targeted understanding this periodic table crossroads where polyoxometalates meets metal‐metal bonded complexes. Here we have isolated green hygroscopic and metastable crystals of (ReVI,oct)2(ReVII,tet)2(OH)2(O)12⋅H2O (ReVI,VII‐green, tet=tetrahedral, oct=octahedral), determined by single‐crystal x‐ray diffraction. In addition to color, Re‐L1 X‐ray absorption near‐edge spectroscopy confirms the reduced oxidation state. ReVI,VII‐green provides the first demonstration of Re autoreduction, long‐observed for Mn and Tc. We also isolated and structurally characterized [Tc4O4(H2O)2(ReO4)14]2− (Tc4Re14) polyanion crystals that contain Tc(V) and Re(VII), consistent with greater stability of reduced Tc compared to reduced Re. Small angle X‐ray scattering of both compounds and prior‐reported polyanion [Tc4O4(H2O)2(TcO4)14]4− (Tc20) dissolved in acetonitrile indicated a qualitative lability order of oxo‐linkages of Re‐O−Re Re‐O−Tc Tc‐O−Tc, and lability of Tc20 was also probed by 99Tc nuclear magnetic resonance spectroscopy. Computation provided insight into 99Tc chemical shifts as well as lability. Based on both reducibility and solution phase dynamics of polynuclear compounds investigated here, Re is an imperfect surrogate for Tc, and further expansion of group VII polyoxometalate chemistry seems promising. KW - XANES KW - Polyoxometalate KW - Technetium PY - 2025 DO - https://doi.org/10.1002/chem.202404144 SN - 0947-6539 VL - 31 IS - 21 SP - 1 EP - 7 PB - Wiley-VCH Verl. AN - OPUS4-65491 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bustamante Pineda, Joana Cecibel A1 - George, Janine T1 - Sulfide-Argyrodites: Thermal properties within the QHA N2 - Argyrodite-type materials have lately sparked a lot of research interest due to their thermoelectric properties. One promising candidate is canfieldite (Ag8SnS6), which has a Pna21 orthorhombic crystal structure at room temperature (RT). Recently, experimentalists have found a new low-temperature (LT) phase transition of canfieldite at 120K. Therefore, we investigate structural, vibrational and thermodynamic properties of Ag8SnS6 at room- and low-temperature employing density-functional theory (DFT) and lattice dynamics computations. Thermal properties calculations were based on the quasi-harmonic approximation (QHA) as implemented in phonopy. We achieve good agreement with experiments. Lattice parameters were overestimated by 2%, and thermal properties such as the constant-pressure heat capacity Cp are very close to experimental measurements. Our simulations also reveal a possible new phase transition at around 312 K. Furthermore, we compared RT and LT Ag8SnS6 Grüneisen parameters with some argyrodites analogues, Ag8TQ6 (T = Si, Ge, Ti and Sn; Q = S, Se), finding a relationship between the anharmonicity and low thermal conductivity. T2 - SALSA Make and Measure Conference CY - Berlin, Germany DA - 13.09.2023 KW - Thermoelectric materials KW - DFT KW - QHA KW - Grüneisen parameter PY - 2023 AN - OPUS4-58368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bustamante Pineda, Joana Cecibel T1 - Lattice thermal conductivity on argyrodite compounds Ag8TS6 (T= Si, Ge and Sn): Experimental and full ab initio approach N2 - Thermoelectric materials offer a promising solution for energy conservation and environmental protection by addressing the significant heat waste in energy production. These innovative materials have the ability to directly convert heat into electricity and vice versa. Here, we have studied the family of Ag8TS6 (T= Sn, Ge, S) by combining experimental and theoretical approaches. We investigated their structural, vibrational and thermodynamic properties employing the Local Orbital Basis Suite Towards Electronic-Structure Reconstruction (LOBSTER), density-functional theory (DFT) and lattice dynamics computations included in the automated workflows in atomate2 software. These structures exhibit lower group and sound velocities, along with higher Grüneisen parameters, primarily influenced by the vibrations of Ag⁺ ions due to their low bonding interaction. Based on a newly introduced two-channel lattice dynamics model[4] including lifetimes stated from Grüneisen parameters (similar to the approach in the Slack model), we were also able to successfully model lattice thermal conductivity and compare these results with experimental measurements. Finally, a bonding analysis of all studied compounds was carried out, indicating a similar bonding situation in all our structures. By using bonding analysis and our model for the lattice thermal conductivity calculations, we demonstrate that the bond heterogeneity found in Ag8SnS6, Ag8GeS6, and Ag8SiS6 is closely connected to its low thermal conductivity, dominated mainly by heat transport via a diffusive exchange of thermal energy between phonon modes (diffusons). T2 - XLVIII International Congress of Theoretical Chemists of Latin Expression CY - Cartagena, Colombia DA - 14.07.2025 KW - Grüneisen parameter KW - LOBSTER KW - DFT KW - QHA PY - 2025 AN - OPUS4-63818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bustamante, Joana A1 - Naik, Aakash A1 - Ueltzen, Katharina A1 - George, Janine A1 - Ertural, Christina T1 - Thermal Transport in Ag8TS6 (T= Si, Ge, Sn) Argyrodites: An Integrated Experimental, Quantum-Chemical, and Computational Modelling Study. DFT-part N2 - This repository contains computational data supporting the manuscript titled *“Thermal Transport in Ag8TS6 (T= Si, Ge, Sn) Argyrodites: An Integrated Experimental, Quantum-Chemical, and Computational Modelling Study”* It includes raw data for vibrational properties, elastic properties and Bonding analysis. KW - DFT KW - QHA KW - Lattice thermal conductivity KW - Grüneisen parameter PY - 2025 DO - https://doi.org/10.5281/zenodo.17399975 PB - Zenodo CY - Geneva AN - OPUS4-64671 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bustamante, Joana A1 - Naik, Aakash A1 - Ueltzen, Katharina A1 - Ertural, Christina A1 - George, Janine T1 - Thermodynamic and Thermoelectric Properties of the Canfieldite, (Ag8SnS6 ), in the Quasi-Harmonic Approximation N2 - Argyrodite-type materials have lately sparked a lot of research interest due to their thermoelectric properties. One promising candidate is canfieldite (Ag8SnS6), which has a Pna21 orthorhombic crystal structure at room temperature (RT). Recently, Slade group found a new low-temperature (LT) phase transition of canfieldite at 120K. Therefore, we investigate structural, vibrational and thermodynamic properties of Ag8SnS6 at room- and low-temperature employing density-functional theory (DFT) and lattice dynamics computations. Thermal properties calculations were based on the quasi-harmonic approximation (QHA) as implemented in phonopy. We achieve good agreement with experiments. Lattice parameters were overestimated by 2%, and thermal properties such as the constant-pressure heat capacity Cp are very close to experimental measurements. Our simulations also reveal a possible new phase transition at around 312 K. Furthermore, we compared RT and LT Ag8SnS6 Grüneisen parameters with some argyrodites analogues, Ag8TS6 (T = Si, Ge, Ti and Sn), finding a relationship between the anharmonicity and low thermal conductivity. T2 - TDEP Summer School 2023 (TDEP2023: Finite-temperature and anharmonic response properties of solids in theory and practice) CY - Linköping, Sweden DA - 20.08.2023 KW - Thermoelectric materials KW - DFT KW - QHA KW - Grüneisen parameter PY - 2023 AN - OPUS4-58147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bustamante, Joana A1 - Naik, Aakash A1 - Ueltzen, Katharina A1 - Ertural, Christina A1 - George, Janine T1 - Thermal Transport in Ag8TS6 (T= Si, Ge, Sn) Argyrodites: An Integrated Experimental, Quantum-Chemical, and Computational Modelling Study. N2 - This repository includes raw data for bonding analysis and lattice thermal conductivity using MLIP-MACE-MP03b, supporting the manuscript “Thermal Transport in Ag8TS6 (T= Si, Ge, Sn) Argyrodites: An Integrated Experimental, Quantum-Chemical, and Computational Modelling Study” KW - DFT KW - LOBSTER KW - Lattice thermal conductivity KW - MLIP PY - 2025 DO - https://doi.org/10.5281/zenodo.17397456 PB - Zenodo CY - Geneva AN - OPUS4-64674 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bustamante, Joana A1 - Naik, Aakash A1 - Ertural, Christina A1 - Ueltzen, Katharina A1 - George, Janine T1 - Thermodynamic and Thermoelectric Properties of the Canfieldite, (Ag8SnS6 ), in the Quasi-Harmonic Approximation N2 - Argyrodite-type materials have lately sparked a lot of research interest due to their thermoelectric properties.One promising candidate is canfieldite (Ag8SnS6), which has a Pna21 orthorhombic crystal structure at room temperature (RT). Recently, a new low-temperature (LT) phase transition of canfieldite at 120K has been found. Here, we investigate structural, vibrational and thermodynamic properties of Ag8SnS6 at room- and low-temperature employing density functional theory (DFT) and lattice dynamics computations. Thermal properties calculations were based on the quasi-harmonic approximation (QHA) as implemented in phonopy. We achieve good agreement with experiments. Thermal properties such as the constant-pressure heat capacity (Cp) and thermal conductivity are very close to experimental measurements. Furthermore, we compared RT and LT Ag8SnS6 Grüneisen parameters with argyrodites analogues, Ag8XS6 (X = Sn, Si, Ge), to arrive at an improved T2 - 16th International conference on materials chemistry (MC16) CY - Dublin, Ireland DA - 03.07.2023 KW - Thermoelectric materials KW - DFT KW - QHA KW - Grüneisen parameter PY - 2023 AN - OPUS4-57887 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bui, Minh A1 - Heinekamp, Christian A1 - Fuhry, Emil A1 - Weidner, Steffen A1 - Radnik, Jörg A1 - Ahrens, Mike A1 - Scheurell, Kerstin A1 - Balasubramanian, Kannan A1 - Emmerling, Franziska A1 - Braun, Thomas T1 - Lewis-acid induced mechanochemical degradation of polyvinylidene fluoride: transformation into valuable products N2 - Polyvinylidene fluoride (–[CH2CF2]n–, PVDF) waste poses significant environmental challenges due to its recalcitrant nature and widespread use. This study addresses the end-of-life management of PVDF by introducing a novel, sustainable mechanochemical approach for its valorisation. We investigated the degradation of PVDF into value-added materials using ball milling with anhydrous AlCl3 to achieve a quantitative mineralisation producing AlF3 and halide-functionalised graphite, along with gaseous products (HCl and CH4). Mechanistic key steps involve Lewis-acid catalysed C–F bond activation, dehydrofluorination and aromatisation. This approach provides an effective solution for PVDF waste management while offering a promising route for the production of high-value materials from polymer waste streams. Our findings contribute to sustainable practices in polymer recycling and resource recovery, respond to pressing environmental concerns associated with fluoropolymer disposal, and demonstrate the potential to convert polymer wastes into useful products. KW - Mechanochemistry KW - Polyvinylidenfluoride KW - Degradation KW - Ball mill PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-649015 DO - https://doi.org/10.1039/d5sc05783c SN - 2041-6520 VL - 16 IS - 40 SP - 18903 EP - 18910 PB - Royal Society of Chemistry (RSC) AN - OPUS4-64901 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -