TY - JOUR A1 - Heinekamp, Christian A1 - Kneiske, Sönke A1 - de Oliveira Guilherme Buzanich, Ana A1 - Ahrens, Mike A1 - Braun, Thomas A1 - Emmerling, Franziska T1 - A fluorolytic sol-gel route to access an amorphous Zr fluoride catalyst: A useful tool for C-F bond activation N2 - A route to a ZrF4 catalyst active in room temperature Friedel–Crafts and dehydrofluorination reactions was developed via a fluorolytic sol–gel route, which was followed by a postfluorination step using a stream of CHClF2. The behaviour of different Zr(IV) precursors in a sol–gel reaction with anhydrous isopropanol/HF solution was investigated. The subsequent post-fluorination step was optimised in its temperature ramp and confirmed the necessity of a fluorination of the generated xerogels to obtain catalytic activity. The process is discussed in the context of the analysis of the materials using Brunauer–Emmett–Teller analysis (BET), powder X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The local structure of the amorphous catalyst was elucidated by extended X-ray absorption fine structure spectroscopy (EXAFS). KW - Catalysis KW - Heterogeneous catalysis KW - C-F bond activation KW - Postfluorination PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593433 DO - https://doi.org/10.1039/D3CY01439H SN - 2044-4761 SP - 1 EP - 8 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Licht, M. A1 - Nikoonasab, Ali A1 - Gluth, Gregor A1 - Raupach, M. ED - Claßen, M. ED - Hegger, J. ED - Matschei, T. ED - Raupach, M. T1 - Alkali-aktivierte Hüttensandbetone – CO2-reduzierte Bindemittel mit hohem Korrosionsschutzpotential N2 - Durch den Ersatz von Portlandzement können alkali-aktivierte Bindemittel einen bedeutenden Beitrag zur Verringerung der durch die Zementklinkerherstellung verursachten CO2-Emissionen leisten. Für die Verwendung von alkali-aktivierten Bindemitteln in Stahlbetonkonstruktionen, die Chloriden oder Carbonatisierung ausgesetzt sind, ist die Fähigkeit des Stahls, den passiven Zustand zu erreichen und aufrechtzuerhalten, von großer Bedeutung. Die Prozesse der Deckschichtbildung von Stahl in alkali-aktivierten Materialien unterscheiden sich jedoch zum Teil grundlegend von denen in Portlandzementen. Alkali-aktivierte Hüttensandbetone weisen gute technische Eigenschaften auf, bisher fehlen jedoch grundlegende Kenntnisse bzgl. ihrer schützenden Wirkung bei korrosiven Angriffen. Dies ist vor allem auf ihre sulfidhaltige Porenlösung zurückzuführen, welche die elektrochemischen Eigenschaften der Stahloberfläche beeinflusst und die Verwendung herkömmlicher Bewertungsmaßstäbe erschwert. Es werden erste Ergebnisse eines DFG-Forschungsprojektes vorgestellt, in dem das Passivierungsverhalten von Stahl in alkali-aktivierten Hüttensandmörteln unterschiedlicher Zusammensetzungen sowie in Mörteln auf Basis hüttensandhaltiger Normzemente untersucht wird. Über einen Zeitraum von mindestens 28 Tagen werden an Zylinderprüfkörpern im 3-Elektroden-Aufbau das Ruhepotential sowie die Polarisationswiderstände der Stahlelektroden ermittelt. T2 - 10. DAfStb-Jahrestagung mit 62. Forschungskolloquium CY - Aachen, Germany DA - 26.09.2023 KW - Bewehrung KW - Stahlkorrosion KW - Hüttensandmehl KW - Sulfid PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593775 DO - https://doi.org/10.18154/RWTH-2023-06676 SP - 233 EP - 238 PB - RWTH Aachen CY - Aachen AN - OPUS4-59377 LA - deu 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 - Kunkel, B. A1 - Kabelitz, Anke A1 - de Oliveira Guilherme Buzanich, Ana A1 - Wohlrab, S. T1 - Increasing the Efficiency of Optimized V-SBA-15 Catalysts in the Selective Oxidation of Methane to Formaldehyde by Artificial Neural Network Modelling N2 - The present study investigates the possibility of improving the selective oxidation of methane to formaldehyde over V-SBA-15 catalysts in two different ways. In a classical approach of catalyst optimization, the in situ synthesis of V-SBA-15 catalysts was optimized with regard to the applied pH value. Among the set of catalysts synthesized, a higher amount of incorporated vanadium, a higher content of polymeric VOx species as well as a less ordered structure of the support material were observed by increasing the pH values from 2.0 to 3.0. An optimum in performance during the selective oxidation of methane to formaldehyde with respect to activity and selectivity was found over V-SBA-15 prepared at a pH value of 2.5. With this knowledge, we have now evaluated the possibilities of reaction control using this catalyst. Specifically, artificial neural network modelling was applied after the collection of 232 training samples for obtaining insight into the influence of different reaction parameters (temperature; gas hourly space velocity (GHSV); and concentration of O2, N2 and H2O) onto methane conversion and selectivity towards formaldehyde. This optimization of reaction conditions resulted in an outstanding high space-time yield of 13.6 kgCH2O∙kgcat∙h−1 KW - Artificial neural network modelling KW - Selective oxidation KW - Molecular VOx catalysts KW - Formaldehyde PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517420 DO - https://doi.org/10.3390/catal10121411 VL - 10 IS - 12 SP - 1411 PB - MDPI AN - OPUS4-51742 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winnefeld, F. A1 - Gluth, Gregor A1 - Bernal, S. A. A1 - Bignozzi, M. C. A1 - Carabba, L. A1 - Chithiraputhiran, S. A1 - Dehghan, A. A1 - Dolenec, S. A1 - Dombrowski-Daube, K. A1 - Dubey, A. A1 - Ducman, V. A1 - Yu, J. A1 - Peterson, K. A1 - Stephan, D. A1 - Provis, J. L. T1 - RILEM TC 247-DTA round robin test: sulfate resistance, alkali-silica reaction and freeze–thaw resistance of alkali-activated concretes N2 - The RILEM technical committee TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ conducted a round robin testing programme to determine the validity of various durability testing methods, originally developed for Portland cement based-concretes, for the assessment of the durability of alkali-activated concretes. The outcomes of the round robin tests evaluating sulfate resistance, alkali-silica reaction (ASR) and freeze–thaw resistance are presented in this contribution. Five different alkali-activated concretes, based on ground granulated blast furnace slag, fly ash, or metakaolin were investigated. The extent of sulfate damage to concretes based on slag or fly ash seems to be limited when exposed to an Na2SO4 solution. The mixture based on metakaolin showed an excessive, very early expansion, followed by a dimensionally stable period, which cannot be explained at present. In the slag-based concretes, MgSO4 caused more expansion and visual damage than Na2SO4; however, the expansion limits defined in the respective standards were not exceeded. Both the ASTM C1293 and RILEM AAR-3.1 test methods for the determination of ASR expansion appear to give essentially reliable identification of expansion caused by highly reactive aggregates. Alkali-activated materials in combination with an unreactive or potentially expansive aggregate were in no case seen to cause larger expansions; only the aggregates of known very high reactivity were seen to be problematic. The results of freeze–thaw testing (with/without deicing salts) of alkali-activated concretes suggest an important influence of the curing conditions and experimental conditions on the test outcomes, which need to be understood before the tests can be reliably applied and interpreted. KW - Alkali-activated materials KW - Sulfate attack KW - Alkali silica reaction KW - Alkali aggregate reaction KW - Freeze-thaw attack PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515527 DO - https://doi.org/10.1617/s11527-020-01562-0 VL - 53 IS - 6 SP - 140 PB - Springer Nature AN - OPUS4-51552 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mundra, Shishir A1 - Provis, J. L. T1 - Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions N2 - The pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film formed on steel reinforcement is poorly understood. This study investigates the critical role of HS− in defining mild steel passivation chemistry. The surface film formed on the steel in alkaline-sulfide solutions contains Fe(OH)2 and Fe–S complexes, and the critical chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior is dependent on the duration of exposure of the steel to the electrolyte, and the nature of the sulfidic surface layer. KW - Alkali-activated materials KW - Steel corrosion KW - Sulfide KW - Chloride PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-528861 DO - https://doi.org/10.1007/s10853-021-06237-x VL - 56 IS - 26 SP - 14783 EP - 14802 PB - Springer Nature AN - OPUS4-52886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Arbi, K. A1 - Bernal, S. A. A1 - Bondar, D. A1 - Castel, A. A1 - Chithiraputhiran, S. A1 - Dehghan, A. A1 - Dombrowski-Daube, K. A1 - Dubey, A. A1 - Ducman, V. A1 - Peterson, K. A1 - Pipilikaki, P. A1 - Valcke, S. L. A. A1 - Ye, G. A1 - Zuo, Y. A1 - Provis, J. L. T1 - RILEM TC 247-DTA round robin test: carbonation and chloride penetration testing of alkali-activated concretes N2 - Many standardised durability testing methods have been developed for Portland cement-based concretes, but require validation to determine whether they are also applicable to alkali-activated materials. To address this question, RILEM TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ carried out round robin testing of carbonation and chloride penetration test methods, applied to five different alkali-activated concretes based on fly ash, blast furnace slag or metakaolin. The methods appeared overall to demonstrate an intrinsic precision comparable to their precision when applied to conventional concretes. The ranking of test outcomes for pairs of concretes of similar binder chemistry was satisfactory, but rankings were not always reliable when comparing alkali-activated concretes based on different precursors. Accelerated carbonation testing gave similar results for fly ash-based and blast furnace slag-based alkali-activated concretes, whereas natural carbonation testing did not. Carbonation of concrete specimens was observed to have occurred already during curing, which has implications for extrapolation of carbonation testing results to longer service life periods. Accelerated chloride penetration testing according to NT BUILD 443 ranked the tested concretes consistently, while this was not the case for the rapid chloride migration test. Both of these chloride penetration testing methods exhibited comparatively low precision when applied to blast furnace slag-based concretes which are more resistant to chloride ingress than the other materials tested. KW - Alkali-activated materials KW - Durability KW - Carbonation KW - Chloride penetration KW - Concrete PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-504045 DO - https://doi.org/10.1617/s11527-020-1449-3 SN - 1359-5997 SN - 1871-6873 VL - 53 IS - 1 SP - 21 PB - Springer Nature AN - OPUS4-50404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Sebastian A1 - Gluth, Gregor ED - Rossignol, S. ED - Gluth, Gregor T1 - Unraveling the hardening mechanism during laser-induced slip casting of lithium aluminate-microsilica slurry N2 - Additive manufacturing (AM) of alkali-activated materials is a promising method for producing ceramic precursors, construction elements and other parts. A recently introduced AM process is laser-induced slip casting of lithium aluminate/microsilica slurries, which yields parts with excellent mechanical strengths. To clarify the underlying mechanisms, μ-Raman spectroscopy was applied to parts produced by the process, and the dissolution and hydration of lithium aluminate was studied inter alia using conventional and in-situ X-ray diffraction. The results show that significant dissolution of lithium aluminate occurs, particularly at increased temperatures during laser interaction, which leads to an increase of pH and precipitation of an akopovaite-like Li-Al-CO3 layered double hydroxide. The increase of the pH is likely to induce dissolution of the microsilica and possibly formation of a hydrous lithium aluminosilicate gel. These observations explain the strength evolution of the studied parts and can also aid the development and improvement of related AM methods. KW - Alkali-activated materials KW - Additive manufacturing KW - Laser-induced slip casting KW - Lithium KW - Layered double hydroxide PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520557 DO - https://doi.org/10.1016/j.oceram.2021.100060 SN - 2666-5395 VL - 5 IS - Special issue: Alkali-activated materials and geopolymers in ceramics and beyond SP - 1 EP - 7 PB - Elsevier CY - Amsterdam AN - OPUS4-52055 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Patrick A1 - Moye, J. A1 - Gluth, Gregor A1 - Vogler, Nico A1 - Taffe, A. A1 - Kühne, Hans-Carsten ED - Rossignol, S. ED - Gluth, Gregor T1 - Properties of alkali-activated mortars with salt aggregate for sealing structures in evaporite rock N2 - Concrete structures for sealing of tunnels in the host rock are an essential part of systems for nuclear waste storage. However, concretes based on blended cements or magnesium oxychloride cements, which are commonly considered for this application, can deteriorate severely due to a significant heat of hydration and associated deformation and cracking. Alkali-activated materials (AAMs) offer a potential solution to this problem because of their low heat release during hardening. To explore their suitability for the construction of sealing structures in evaporite rock, various AAMs with salt aggregate were studied regarding fresh properties, heat release, mechanical properties and microstructure. The heat of reaction of the AAMs was up to 55% lower than that of a blended cement designed for sealing structures, indicating significant benefits for the intended application. Other relevant properties such as mechanical strength and permeability depended strongly on the mix-design of the AAMs and curing conditions. KW - Alkali-activated materials KW - Geopolymers KW - Nuclear waste storage KW - Sealing structures KW - Evaporite rock PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519422 DO - https://doi.org/10.1016/j.oceram.2020.100041 SN - 2666-5395 VL - 5 IS - Special issue: Alkali-activated materials and geopolymers in ceramics and beyond SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-51942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lumpe, H. A1 - Menke, Annika A1 - Haisch, C. A1 - Mayer, P. A1 - Kabelitz, Anke A1 - Yusenko, Kirill A1 - de Oliveira Guilherme Buzanich, Ana A1 - Block, T. A1 - Pöttgen, R. A1 - Emmerling, Franziska A1 - Daumann, L. T1 - The Earlier the Better: Structural Analysis and Separation of Lanthanides with Pyrroloquinoline Quinone N2 - Lanthanides (Ln) are critical raw materials, however, their mining and purification have a considerable negative environmental impact and sustainable recycling and separation strategies for these elements are needed. In this study, the precipitation and solubility behavior of Ln complexes with pyrroloquinoline quinone (PQQ), the cofactor of recently discovered lanthanide (Ln) dependent methanol dehydrogenase (MDH) enzymes, is presented. In this context, the molecular structure of a biorelevant europium PQQ complex was for the first time elucidated outside a protein environment. The complex crystallizes as an inversion symmetric dimer, Eu2PQQ2, with binding of Eu in the biologically relevant pocket of PQQ. LnPQQ and Ln1Ln2PQQ complexes were characterized by using inductively coupled plasma mass spectrometry (ICP‐MS), infrared (IR) spectroscopy, 151Eu‐Mössbauer spectroscopy, X‐ray total scattering, and extended X‐ray absorption fine structure (EXAFS). It is shown that a natural enzymatic cofactor is capable to achieve separation by precipitation of the notoriously similar, and thus difficult to separate, lanthanides to some extent. KW - PQQ KW - Lanthanoide KW - Coordination chemistry KW - Rare earth elements separations PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512707 DO - https://doi.org/10.1002/chem.202002653 VL - 26 IS - 44 SP - 10133 EP - 10139 AN - OPUS4-51270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radtke, Martin A1 - Rakotondrajoa, A. T1 - Machine learning based quantification of synchrotron radiation-induced X-ray fluorescence measurements - a case study N2 - In this work, we describe the use of artificial neural networks for the quantification of X-ray fluorescence measurements. The training data were generated using Monte Carlo simulation, which avoided the use of adapted reference materials. The extension of the available data set by means of an ANN to generate additional data was demonstrated. Particular emphasis was put on the comparability of simulated and experimental data and how the influence of deviations can be reduced. The search for the optimal hyperparameter, manual and automatic, is also described. For the presented case, we were able to train a network with a mean absolute error of 0.1 weight percent for the synthetic data and 0.7 weight percent for a set of experimental data obtained with certified reference materials. KW - Machine learning KW - BAMline KW - XRF KW - Synchrotron KW - Neural network PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519008 DO - https://doi.org/10.1088/2632-2153/abc9fb SP - 1 EP - 16 PB - IOP Publishing AN - OPUS4-51900 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hüsken, Götz A1 - Wagner, L.-C. A1 - Gluth, Gregor A1 - Pirskawetz, Stephan A1 - Kühne, Hans-Carsten T1 - Application of Steel Fibres in Alkali-Activated Mortars N2 - Alkali-activated materials are ideal for the repair of concrete structures in harsh environmental conditions due to their high durability in chemically aggressive environments. However, slag-based mortars, in particular, are prone to shrinkage and associated cracks. In this respect, the application of steel fibres is one solution to reduce the formation of shrinkage induced cracks and to improve post cracking behaviour of these mortars. This study investigated the influence of two different types of steel fibres on the tensile properties of two alkali-activated mortars. Direct tensile tests and single fibre pull-outs were performed to analyse the determining failure modes both on macro and micro scale. Mechanical testing was accompanied by non-destructive testing methods such as digital image correlation and acoustic emission for a detailed analysis of the fracture process. T2 - Local Mechanical Properties - LMP 2019 CY - Prague, Czech Republic DA - 06.11.2019 KW - Alkali-activated materials KW - Fibre pull-out KW - Steel fibres KW - Tensile strength PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509291 UR - https://ojs.cvut.cz/ojs/index.php/APP/article/view/6695 DO - https://doi.org/10.14311/APP.2020.27.0090 VL - 27 SP - 90 EP - 95 CY - Prague, Czech Republic AN - OPUS4-50929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Smekhova, A. A1 - Kuzmin, A. A1 - Siemensmeyer, K. A1 - Luo, C. A1 - Taylor, J. A1 - Thakur, S. A1 - Radu, F. A1 - Weschke, E. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Xiao, B. A1 - Savan, A. A1 - Yusenko, Kirill A1 - Ludwig, A. T1 - Local structure and magnetic properties of a nanocrystalline Mn-rich Cantor alloy thin film down to the atomic scale N2 - The huge atomic heterogeneity of high-entropy materials along with a possibility to unravel the behavior of individual components at the atomic scale suggests a great promise in designing new compositionally complex systems with the desired multi-functionality. Herein, we apply multi-edge X-ray absorption spectroscopy (extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), and X-ray magnetic circular dichroism (XMCD)) to probe the structural, electronic, and magnetic properties of all individual constituents in the single-phase face-centered cubic (fcc)-structured nanocrystalline thin film of Cr20Mn26Fe18Co19Ni17 (at.%) high-entropy alloy on the local scale. The local crystallographic ordering and component-dependent lattice displacements were explored within the reverse Monte Carlo approach applied to EXAFS spectra collected at the K absorption edges of several constituents at room temperature. A homogeneous short-range fcc atomic environment around the absorbers of each type with very similar statistically averaged interatomic distances (2.54–2.55 Å) to their nearest-neighbors and enlarged structural relaxations of Cr atoms were revealed. XANES and XMCD spectra collected at the L2,3 absorption edges of all principal components at low temperature from the oxidized and in situ cleaned surfaces were used to probe the oxidation states, the changes in the electronic structure, and magnetic behavior of all constituents at the surface and in the sub-surface volume of the film. The spin and orbital magnetic moments of Fe, Co, and Ni components were quantitatively evaluated. The presence of magnetic phase transitions and the co-existence of different magnetic phases were uncovered by conventional magnetometry in a broad temperature range. KW - Magnetism KW - High-entropy alloys KW - Reverse Monte Carlo (RMC) KW - Element-specific spectroscopy KW - Extended X-ray absorption fine structure (EXAFS), KW - X-ray magnetic circular dichroism (XMCD), PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-578254 DO - https://doi.org/10.1007/s12274-022-5135-3 SN - 1998-0124 SP - 5626 PB - Springer AN - OPUS4-57825 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rudić, O. A1 - Mittermayr, F. A1 - Gluth, Gregor A1 - Simon, Sebastian A1 - Ukrainczyk, N. A1 - Seyrek, Y. A1 - Freytag, B. A1 - Juhart, J. A1 - Grengg, C. T1 - On the benefits of vegetable oil addition for the pore structure and acid resistance of alkali-activated systems N2 - The impact of high additions of vegetable oil (12 vol%) on the mechanical and microstructural properties of metakaolin-slag-based alkali-activated materials (AAMs) was studied. The addition of oil resulted in a slight decrease in initial polymerization kinetics but did not affect the final degree of reaction. AAM-oil-composite-mortars exhibited approximately ∼30% lower compressive strength primarily due to the entrainment of air voids. Newly formed soap phases significantly reduced the volume of small capillary and gel pores (pore radii <15 nm), leading to a decrease in specific inner surface area by a factor of up to 15. The porosity modification induced by the oil addition greatly enhanced the resistance of AAMs against sulfuric acid attack, shifting the dominant processes from diffusion and cracks to framework-dissolution controlled by the inherent phase stabilities. Following the immersion in sulfuric acid (pHstat = 2) for 8 weeks, the depth of corroded layer decreased by 70% and no cracks due to expansive phases were observed. These promising findings suggest that the incorporation of vegetable oil in AAMs has the potential to address durability concerns associated with diffusion-based corrosion processes, thereby expanding the range of future applications. KW - Alkali-activated materials KW - Acid resistance KW - Pore structure PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581719 DO - https://doi.org/10.1016/j.ceramint.2023.08.036 VL - 49 IS - 20 SP - 33275 EP - 33290 PB - Elsevier Ltd. AN - OPUS4-58171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mundra, S. A1 - Samson, G. A1 - Masi, G. A1 - Achenbach, R. A1 - Bastidas, D. M. A1 - Bernal, S. A. A1 - Bignozzi, M. C. A1 - Criado, M. A1 - Cyr, M. A1 - Gartner, N. A1 - von Greve-Dierfeld, S. A1 - Legat, A. A1 - Nikoonasab, Ali A1 - Provis, J. L. A1 - Raupach, M. A1 - Gluth, Gregor T1 - Application of electrochemical methods for studying steel corrosion in alkali-activated materials N2 - Alkali-activated materials (AAMs) are binders that can complement and partially substitute the current use of conventional cement. However, the present knowledge about how AAMs protect steel reinforcement in concrete elements is incomplete, and uncertainties exist regarding the application of electrochemical methods to investigate this issue. The present review by EFC WP11-Task Force ‘Corrosion of steel in alkali-activated materials’ demonstrates that important differences exist between AAMs and Portland cement, and between different classes of AAMs, which are mainly caused by differing pore solution compositions, and which affect the outcomes of electrochemical measurements. The high sulfide concentrations in blast furnace slag-based AAMs lead to distinct anodic polarisation curves, unusually low open circuit potentials, and low polarisation resistances, which might be incorrectly interpreted as indicating active corrosion of steel reinforcement. No systematic study of the influence of the steel–concrete interface on the susceptibility of steel to corrosion in AAMs is available. Less common electrochemical methods present an opportunity for future progress in the field. KW - Alkali-activated materials KW - Reinforcement corrosion KW - Steel corrrosion KW - Electrochemical methods KW - Concrete PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-572241 DO - https://doi.org/10.1002/maco.202313743 SN - 1521-4176 VL - 74 IS - 7 SP - 988 EP - 1008 PB - Wiley-VCH CY - Weinheim AN - OPUS4-57224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Peters, Stefan A1 - Kunkel, Benny A1 - Cakir, Cafer Tufan A1 - Kabelitz, Anke A1 - Witte, Steffen A1 - Bernstein, Thomas A1 - Bartling, Stephan A1 - Radtke, Martin A1 - Emmerling, Franziska A1 - Abdel-Mageed, Ali Mohamed A1 - Wohlrab, Sebastian A1 - de Oliveira Guilherme Buzanich, Ana T1 - Time-, space- and energy-resolved in situ characterization of catalysts by X-ray absorption spectroscopy N2 - A novel setup for dispersive X-ray absorption spectroscopy (XAS) with simultaneous resolution of space, time and energy for in situ characterization of solid materials is demonstrated. KW - Dispersive XAS KW - Catalysis KW - In situ KW - Structure analysis PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584924 DO - https://doi.org/10.1039/d3cc03277a SN - 1359-7345 SP - 1 EP - 4 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karafiludis, Stephanos A1 - Ryll, T. W. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Emmerling, Franziska A1 - Stawski, Tomasz Maciej T1 - Phase stability studies on transition metal phosphates aided by an automated synthesis N2 - Transition metal phosphates (TMPs) have attracted interest as materials for (electro-) catalysis, and electrochemistry due to their low-cost, stability, and tunability. In this work, an automated synthesis platform was used for the preparation of transition metal phosphate crystals to efficiently explore the multidimensional parameter space, determining the phase selection, crystal sizes, shapes. By using X-ray diffraction and spectroscopy-based methods and electron microscopy imaging, a complete characterization of the phase stability fields, phase transitions, and crystal morphology/sizes was achieved. In an automated three-reactant synthesis, the individual effect of each reactant species NH4+, M2+, and PO43- on the formation of transition metal phosphate phases: M-struvite NH4MPO4·6H2O, M-phosphate octahydrate M3(PO4)2·8H2O with M = Ni, Co and an amorphous phase, was investigated. The NH4+ concentration dictates the phase composition, morphology, and particle size in the Ni-system (crystalline Ni-struvite versus amorphous Ni-PO4 phase), whereas in the Co-system all reactant species - NH4+, Co2+, and PO43- - influence the reaction outcome equivalently (Co-struvite vs. Co-phosphate octahydrate). The coordination environment for all crystalline compounds and of the amorphous Ni-PO4 phase was resolved by X-ray absorption spectroscopy, revealing matching characteristics to its crystalline analogue, Ni3(PO4)2·8H2O. The automated synthesis turned out to be significantly advantageous for the exploration of phase diagrams due to its simple modularity, facile traceability, and enhanced reproducibility compared to a typical manual synthesis. KW - Automated synthesis KW - Phase diagrams KW - Transition metals KW - Phosphates KW - Local structure KW - Struvite PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-579151 DO - https://doi.org/10.1039/D3CE00386H VL - 25 IS - 30 SP - 4333 EP - 4344 PB - CrystEngComm CY - London AN - OPUS4-57915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana A1 - Cakir, Cafer Tufan A1 - Radtke, Martin A1 - Haider, M. Bilal A1 - Emmerling, Franziska A1 - F. M. Oliveira, P. A1 - Michalchuk, Adam T1 - Dispersive x-ray absorption spectroscopy for time-resolved in situ monitoring of mechanochemical reactions N2 - X-ray absorption spectroscopy (XAS) provides a unique, atom-specific tool to probe the electronic structure of solids. By surmounting long-held limitations of powder-based XAS using a dynamically averaged powder in a Resonant Acoustic Mixer (RAM), we demonstrate how time-resolved in situ (TRIS) XAS provides unprecedented detail of mechanochemical synthesis. The use of a custom-designed dispersive XAS (DXAS) setup allows us to increase the time resolution over existing fluorescence measurements from ∼15 min to 2 s for a complete absorption spectrum. Hence, we here establish TRIS-XAS as a viable method for studying mechanochemical reactions and sampling reaction kinetics. The generality of our approach is demonstrated through RAM-induced (i) bottom-up Au nanoparticle mechanosynthesis and (ii) the synthesis of a prototypical metal organic framework, ZIF-8. Moreover, we demonstrate that our approach also works with the addition of a stainless steel milling ball, opening the door to using TRIS-DXAS for following conventional ball milling reactions. We expect that our TRIS-DXAS approach will become an essential part of the mechanochemical tool box. KW - In situ studies KW - Dipsersive XAS KW - Mechanochemistry KW - Time-resolved PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567659 DO - https://doi.org/10.1063/5.0130673 SN - 1089-7690 VL - 157 IS - 21 SP - 1 EP - 12 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-56765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinekamp, Christian A1 - de Oliveira Guilherme Buzanich, Ana A1 - Ahrens, M. A1 - Braun, T. A1 - Emmerling, Franziska T1 - An amorphous Lewis-acidic zirconium chlorofluoride as HF shuttle: C–F bond activation and formation N2 - An exceptional HF transfer reaction by C–F bond activation of fluoropentane and a subsequent hydrofluorination of alkynes at room temperature is reported. An amorphous Lewis-acidic Zr chlorofluoride serves as heterogeneous catalyst, which is characterised by an eightfold coordination environment at Zr including chlorine atoms. The studies are seminal in establishing sustainable fluorine chemistry. KW - ZCF KW - Heterogeneous catalysis KW - C-F bond activation KW - HF-shuttle PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582249 DO - https://doi.org/10.1039/D3CC03164K SN - 1359-7345 VL - 59 IS - 75 SP - 11224 EP - 11227 PB - RSC CY - Cambridge AN - OPUS4-58224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vollpracht, A. A1 - Gluth, Gregor A1 - Rogiers, B. A1 - Uwanuakwa, I. D. A1 - Phung, Q. T. A1 - Villagran Zaccardi, Y. A1 - Thiel, C. A1 - Vanoutrive, H. A1 - Etcheverry, J. M. A1 - Gruyaert, E. A1 - Kamali-Bernard, S. A1 - Kanellopoulos, A. A1 - Zhao, Z. A1 - Martins, I. M. A1 - Rathnarajan, S. A1 - De Belie, N. T1 - Report of RILEM TC 281-CCC: insights into factors affecting the carbonation rate of concrete with SCMs revealed from data mining and machine learning approaches N2 - The RILEM TC 281–CCC ‘‘Carbonation of concrete with supplementary cementitious materials’’ conducted a study on the effects of supplementary cementitious materials (SCMs) on the carbonation rate of blended cement concretes and mortars. In this context, a comprehensive database has been established, consisting of 1044 concrete and mortar mixes with their associated carbonation depth data over time. The dataset comprises mix designs with a large variety of binders with up to 94% SCMs, collected from the literature as well as unpublished testing reports. The data includes chemical composition and physical properties of the raw materials, mix-designs, compressive strengths, curing and carbonation testing conditions. Natural carbonation was recorded for several years in many cases with both indoor and outdoor results. The database has been analysed to investigate the effects of binder composition and mix design, curing and preconditioning, and relative humidity on the carbonation rate. Furthermore, the accuracy of accelerated carbonation testing as well as possible correlations between compressive strength and carbonation resistance were evaluated. One approach to summerise the physical and chemical resistance in one parameter is the ratio of water content to content of carbonatable CaO (w/CaOreactive ratio). The analysis revealed that the w/CaOreactive ratio is a decisive factor for carbonation resistance, while curing and exposure conditions also influence carbonation. Under natural exposure conditions, the carbonation data exhibit significant variations. Nevertheless, probabilistic inference suggests that both accelerated and natural carbonation processes follow a square-root-of-time behavior, though accelerated and natural carbonation cannot be converted into each other without corrections. Additionally, a machine learning technique was employed to assess the influence of parameters governing the carbonation progress in concretes. KW - Carbonation KW - Supplementary cementitious materials KW - Concrete PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614388 DO - https://doi.org/10.1617/s11527-024-02465-0 SN - 1871-6873 SN - 1359-5997 VL - 57 IS - 9 SP - 1 EP - 33 PB - Springer Nature AN - OPUS4-61438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Coburger, Peter A1 - de Oliveira Guilherme Buzanich, Ana A1 - Emmerling, Franziska A1 - Abbenseth, Josh T1 - Combining geometric constraint and redox non-innocence within an ambiphilic PBiP pincer ligand N2 - The first pincer ligand featuring a strictly T-shaped pnictogen donor moiety was synthesised. The PBiP ligand's redox activity facilitates unprecedented ambiphilic bonding of the Bi centre with transition metals through the Bi(6p) orbital. KW - EXAFS KW - Pincer Ligand KW - Group 15 metals PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611113 DO - https://doi.org/10.1039/D4SC00197D SN - 2041-6520 SP - 1 EP - 8 PB - Royal Society of Chemistry (RSC) AN - OPUS4-61111 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lima, G. T. S. A1 - Silvestro, L. A1 - Durlo Tambara, Luís Urbano A1 - Cheriaf, M. A1 - Rocha, J. C. T1 - Autonomous Self-Healing Agents in Cementitious Materials: Parameters and Impacts on Mortar Properties N2 - The concept of self-healing materials and the development of encapsulated curing agents represent a cutting-edge approach to enhancing the longevity and reducing the maintenance costs of cementitious structures. This systematic literature review aims to shed light on the parameters involved in the autonomous self-healing of cementitious materials, utilizing various encapsulated healing agents such as pellets, granules, and capsules. This review also identifies and selects studies that offer additional insights into the efficacy of the self-healing process in cementitious materials and the influence of these specific encapsulated healing agents on the physical mechanical properties of mortars. This comprehensive approach provides a deep understanding of the interplay between self-healing and the physical–mechanical properties of mortars containing these encapsulated healing agents. The main findings indicate that the cement-to-sand ratio, characteristics of fine aggregates, and encapsulation methods significantly impact crack control, self-healing efficiency, and properties of mortar in both fresh and hardened states. The content of encapsulated healing agents within the cementitious matrix affects both the initial workability or flow and subsequent mechanical properties. While pellets coated with PVA film typically reduce workability in the fresh state and compressive strength, capsules coated with Portland cement and sodium silicate mitigate these effects and improve crack sealing in fresh and hardened states without compromising the self-healing capacity of cracks. The three-point flexural test has emerged as the preferred method for a pre-crack assessment over 28 days, with variations depending on the type of healing agent used. As noted in the literature, water has been identified as the optimal environment for autonomous healing. These findings underscore the potential of encapsulation techniques to enhance self-healing capabilities through the controlled release of agents within the cementitious matrix, thereby advancing the research on and development of intelligent construction materials and increasing the durability of cement-based structures. KW - Self-healing cementitious composite KW - Encapsulated curing agents KW - Pellets KW - Granules KW - Capsules KW - Physical–mechanical properties KW - Autonomous self-healing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611860 DO - https://doi.org/10.3390/buildings14072000 SN - 2075-5309 VL - 14 IS - 7 SP - 1 EP - 23 PB - MDPI CY - Basel AN - OPUS4-61186 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tu, Z. A1 - Donskyi, Ievgen A1 - Qiao, H. A1 - Zhu, Z. A1 - Unger, Wolfgang A1 - Hackenberger, C. P. R. A1 - Chen, W. A1 - Adeli, M. A1 - Haag, R. T1 - Graphene Oxide-Cyclic R10 Peptide Nuclear Translocation Nanoplatforms for the Surmounting of Multiple-Drug Resistance N2 - Multidrug resistance resulting from a variety of defensive pathways in Cancer has become a global concern with a considerable impact on the mortality associated with the failure of traditional chemotherapy. Therefore, further research and new therapies are required to overcome this challenge. In this work, a cyclic R10 peptide (cR10) is conjugated to polyglycerol-covered nanographene oxide to engineer a nanoplatform for the surmounting of multidrug resistance. The nuclear translocation of the nanoplatform, facilitated by cR10 peptide, and subsequently, a laser-triggered release of the loaded doxorubicin result in efficient anticancer activity confirmed by both in vitro and in vivo experiments. The synthesized nanoplatform with a combination of different features, including active nucleus-targeting, highloading capacity, controlled release of cargo, and photothermal property, provides a new strategy for circumventing multidrug resistant cancers. KW - Graphen Oxide KW - Nanoplatform KW - Cancer PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510061 DO - https://doi.org/10.1002/adfm.202000933 VL - 30 IS - 35 SP - 2000933 PB - Wiley VCH AN - OPUS4-51006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulka, M.W. A1 - Nie, C. A1 - Nickl, P. A1 - Kerkhoff, Y. A1 - Garg, A. A1 - Salz, D. A1 - Radnik, Jörg A1 - Grunwald, I. A1 - Haag, R. T1 - Surface-Initiated Grafting of Dendritic Polyglycerol from Mussel-Inspired Adhesion-Layers for the Creation of Cell-Repelling Coatings N2 - Biofouling is a major challenge in the application of textiles, biosensors, and biomedical implants. In the current work, a straightforward method for the solvent-free polymerization of antifouling dendritic polyglycerol (dPG) from mussel-inspired dendritic polyglycerol (MI-dPG) coatings on hydrophilic titanium dioxide (TiO2) and hydrophobic polydimethylsiloxane (PDMS) is reported. Surface characterization is performed by static water contact angle (CA) measurements, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Significant lower CA values are obtained after dPG grafting from MI-dPG-coated TiO2 and MI-dPG coated PDMS. Furthermore, XPS shows a time-dependent increase of the CO bond content upon dPG grafting from MI-dPG-coated TiO2 and MI-dPG-coated PDMS. Analysis of the surface morphology by SEM shows a clear time-dependent increase in the surface roughness upon dPG grafting from MI-dPG-coated TiO2 and MIdPG-coated PDMS. When the viability of two adhesive cell types is studied via LIVE/DEAD staining, a strong reduction in the cell density is observed after the dPG grafting from MI-dPG-coated TiO2 and MI-dPG-coated PDMS (a decrease of >95% in all cases). The combined results show that biocompatible but highly cell-repelling surfaces are efficiently constructed via the grafting of dPG from MI-dPG-coated TiO2 and MI-dPG-coated PDMS. KW - Repelling surface coatings KW - Dendritic polyglycerol KW - Mussel-inspired adhesives KW - Surface-initated grafting PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516590 DO - https://doi.org/10.1002/admi.202000931 SN - 2196-7350 VL - 7 IS - 24 SP - 931 PB - Wiley VCH AN - OPUS4-51659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weigert, Florian A1 - Müller, A. A1 - Häusler, I. A1 - Geißler, Daniel A1 - Skroblin, D. A1 - Unger, Wolfgang A1 - Radnik, Jörg A1 - Resch-Genger, Ute T1 - Combining HR‑TEM and XPS to elucidate the core–shell structure of ultrabright CdSe/CdS semiconductor quantum dots N2 - Controlling thickness and tightness of surface passivation shells is crucial for many applications of core–shell nanoparticles (NP). Usually, to determine shell thickness, core and core/shell particle are measured individually requiring the availability of both nanoobjects. This is often not fulfilled for functional nanomaterials such as many photoluminescent semiconductor quantum dots (QD) used for bioimaging, solid state lighting, and display technologies as the core does not show the applicationrelevant functionality like a high photoluminescence (PL) quantum yield, calling for a whole nanoobject approach. By combining high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), a novel whole nanoobject approach is developed representatively for an ultrabright oleic acid-stabilized, thick shell CdSe/CdS QD with a PL quantum yield close to unity. The size of this spectroscopically assessed QD, is in the range of the information depth of usual laboratory XPS. Information on particle size and monodispersity were validated with dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) and compared to data derived from optical measurements. In addition to demonstrating the potential of this novel whole nanoobject approach for determining architectures of small nanoparticles, the presented results also highlight challenges faced by different sizing and structural analysis methods and method-inherent uncertainties. KW - Photoluminescence KW - Single particle KW - Microscopy KW - Particle architecture KW - Thickness KW - SAXS KW - Shell KW - XPS KW - TEM KW - Semiconductor KW - Quantum dot KW - Photophysics KW - Quantum yield PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517911 DO - https://doi.org/10.1038/s41598-020-77530-z VL - 10 IS - 1 SP - 20712 PB - Springer Nature AN - OPUS4-51791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Anja A1 - Krahl, T. A1 - Radnik, Jörg A1 - Wagner, Andreas A1 - Werner, W. S. M. A1 - Ritter, B. A1 - Kemnitz, E. A1 - Unger, Wolfgang T1 - Chemical in-depth analysis of (Ca/Sr)F2 core–shell like nanoparticles by X-ray photoelectron spectroscopy with tunable excitation energy N2 - The fluorolytic sol–gel synthesis is applied with the intention to obtain two different types of core–shell nanoparticles, namely, SrF2–CaF2 and CaF2–SrF2. In two separate fluorination steps for core and shell formation, the corresponding metal lactates are reacted with anhydrous HF in ethylene glycol. Scanning transmission electron microscopy (STEM) and dynamic light scattering (DLS) confirm the formation of particles with mean dimensions between 6.4 and 11.5 nm. The overall chemical composition of the particles during the different reaction steps is monitored by quantitative Al Kα excitation X-ray photoelectron spectroscopy (XPS). Here, the formation of stoichiometric metal fluorides (MF2) is confirmed, both for the core and the final core–shell particles. Furthermore, an in-depth analysis by synchrotron radiation XPS (SR-XPS) with tunable excitation energy is performed to confirm the core–Shell character of the nanoparticles. Additionally, Ca2p/Sr3d XPS intensity ratio in-Depth profiles are simulated using the software Simulation of Electron Spectra for Surface Analysis (SESSA). In principle, core–shell like particle morphologies are formed but without a sharp interface between calcium and strontium containing phases. Surprisingly, the in-depth chemical distribution of the two types of nanoparticles is equal within the error of the experiment. Both comprise a SrF2-rich core domain and CaF2-rich shell domain with an intermixing zone between them. Consequently, the internal morphology of the final nanoparticles seems to be independent from the synthesis chronology. KW - Metal fluorides KW - Sol-gel synthesis KW - Synchrotron radiation KW - X-ray photoelectron spectroscopy PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522284 DO - https://doi.org/10.1002/sia.6937 SN - 0142-2421 VL - 53 IS - 5 SP - 494 EP - 508 PB - Wiley VCH AN - OPUS4-52228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bennet, Francesca A1 - Müller, Anja A1 - Radnik, Jörg A1 - Hachenberger, Y. A1 - Jungnickel, H. A1 - Laue, P. A1 - Luch, A. A1 - Tentschert, J. T1 - Preparation of Nanoparticles for ToF-SIMS and XPS Analysis N2 - Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, chemistry, and their potential to enable advanced materials. To effectively understand and regulate the physico-chemical properties and potential adverse effects of nanoparticles, validated measurement procedures for the various properties of nanoparticles need to be developed. While procedures for measuring nanoparticle size and size Distribution are already established, standardized methods for analysis of their surface chemistry are not yet in place, although the influence of the surface chemistry on nanoparticle properties is undisputed. In particular, storage and preparation of nanoparticles for surface analysis strongly influences the analytical results from various methods, and in order to obtain consistent results, sample preparation must be both optimized and standardized. In this contribution, we present, in detail, some standard procedures for preparing nanoparticles for surface analytics. In principle, nanoparticles can be deposited on a suitable substrate from suspension or as a powder. Silicon (Si) Wafers are commonly used as substrate, however, their cleaning is critical to the process. For sample preparation from suspension, we will discuss drop-casting and spin-coating, where not only the cleanliness of the substrate and purity of the suspension but also its concentration play important roles for the success of the preparation methodology. For nanoparticles with sensitive ligand shells or coatings, deposition as powders is more suitable, although this method requires particular care in fixing the sample. KW - Titania nanoparticles KW - X-ray photoelectron spectroscopy KW - Secondary ion mass spectrometry KW - Surface chemisttry PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520103 UR - https://www.jove.com/video/61758 DO - https://doi.org/10.3791/61758 VL - 163 SP - e61758 AN - OPUS4-52010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Nie, C. A1 - Ludwig, K. A1 - Trimpert, J. A1 - Ahmed, R. A1 - Quaas, E. A1 - Achazi, K. A1 - Radnik, Jörg A1 - Adeli, M. A1 - Haag, R. A1 - Osterrieder, K. T1 - Graphene Sheets with Defined Dual Functionalities for the Strong SARS-CoV-2 Interactions N2 - Search of new strategies for the inhibition of respiratory viruses is one of the urgent health challenges worldwide, as most of the current therapeutic agents and treatments are inefficient. Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) has caused a pandemic and has taken lives of approximately two Million people to date. Even though various vaccines are currently under development, virus, and especially its spike glycoprotein can mutate, which highlights a Need for a broad-spectrum inhibitor. In this work, inhibition of SARS-CoV-2 by graphene platforms with precise dual sulfate/alkyl functionalities is investigated. A series of graphene derivatives with different lengths of aliphatic chains is synthesized and is investigated for their ability to inhibit SARS-CoV-2 and feline coronavirus. Graphene derivatives with long alkyl chains (>C9) inhibit coronavirus replication by virtue of disrupting viral envelope. The ability of these graphene platforms to rupture viruses is visualized by atomic force microscopy and cryogenic electron microscopy. A large concentration window (10 to 100-fold) where graphene platforms display strongly antiviral activity against native SARS-CoV-2 without significant toxicity against human cells is found. In this concentration range, the synthesized graphene platforms inhibit the infection of enveloped viruses efficiently, opening new therapeutic and metaphylactic avenues against SARS-CoV-2. KW - Graphene KW - Graphene-based polyglycerol sulfates KW - SARS-CoV2 inhibitor KW - Virucidality PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520858 DO - https://doi.org/10.1002/smll.202007091 VL - 17 IS - 11 SP - 7091 PB - Wiley VCH AN - OPUS4-52085 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hünger, K.-J. A1 - Kositz, M. A1 - Danneberg, M. A1 - Radnik, Jörg T1 - Enrichment of aluminium in the near‐surface region of natural quartzite rock after aluminium exposure N2 - Alkali–silica reaction (ASR) is an ongoing problem that causes damage to concrete constructions and reduces their durability. Therefore, minimizing this undesired reaction is of great interest for both safety and economic reasons. Additives containing high aluminium content are very effective in reducing the release of silica and enhancing the durability of concrete; however, the mechanism for this effect is still under discussion. In this study, an enrichment of aluminium in the near‐surface region was observed for natural quartzite rock after storage in Al (OH)3 and metakaolin as aluminium sources, from which we conclude that the formation of aluminosilicate sheets of a few nanometres inhibits the silica release; this hypothesis is supported by high‐resolution spectra of Al 2p, Si 2p and O 1s. KW - Alkali-silica reaction KW - Quartzite rock KW - X-ray photoelectron spectroscopy PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519394 DO - https://doi.org/10.1002/sia.6918 SN - 0142-2421 SP - 1 EP - 7 PB - Wiley VCH AN - OPUS4-51939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radnik, Jörg A1 - Knigge, Xenia A1 - Andresen, Elina A1 - Resch-Genger, Ute A1 - Cant, D.J.H. A1 - Shard, A.G. A1 - Clifford, C.A. T1 - Composition, thickness, and homogeneity of the coating of core–shell nanoparticles—possibilities, limits, and challenges of X-ray photoelectron spectroscopy N2 - Core–shell nanoparticles have attracted much attention in recent years due to their unique properties and their increasing importance in many technological and consumer products. However, the chemistry of nanoparticles is still rarely investigated in comparison to their size and morphology. In this review, the possibilities, limits, and challenges of X-ray photoelectron spectroscopy (XPS) for obtaining more insights into the composition, thickness, and homogeneity of nanoparticle coatings are discussed with four examples: CdSe/CdS quantum dots with a thick coating and a small core; NaYF4-based upconverting nanoparticles with a large Yb-doped core and a thin Er-doped coating; and two types of polymer nanoparticles with a poly(tetrafluoroethylene) core with either a poly(methyl methacrylate) or polystyrene coating. Different approaches for calculating the thickness of the coating are presented, like a simple numerical modelling or a more complex simulation of the photoelectron peaks. Additionally, modelling of the XPS background for the investigation of coating is discussed. Furthermore, the new possibilities to measure with varying excitation energies or with hard-energy X-ray sources (hard-energy X-ray photoelectron spectroscopy) are described. A discussion about the sources of uncertainty for the determination of the thickness of the coating completes this review. KW - X-ray spectroscopy KW - Nanoparticles KW - Spectroscopy / Instrumentation KW - Spectroscopy / Theory PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-548305 DO - https://doi.org/10.1007/s00216-022-04057-9 VL - 414 IS - 15 SP - 4331 EP - 4345 PB - SpringerNature AN - OPUS4-54830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rautenberg, Max A1 - Gernhard, M. A1 - Radnik, Jörg A1 - Witt, Julia A1 - Roth, C. A1 - Emmerling, Franziska T1 - Mechanochemical synthesis of fluorine-containing Co-doped zeolitic imidazolate frameworks for producing electrocatalysts N2 - Catalysts derived from pyrolysis of metal organic frameworks (MOFs) are promising candidates to replace expensive and scarce platinum-based electrocatalysts commonly used in polymer electrolyte membrane fuel cells. MOFs contain ordered connections between metal centers and organic ligands. They can be pyrolyzed into metal- and nitrogen-doped carbons, which show electrocatalytic activity toward the oxygen reduction reaction (ORR). Furthermore, metal-free heteroatom-doped carbons, such as N-F-Cs, are known for being active as well. Thus, a carbon material with Co-N-F doping could possibly be even more promising as ORR electrocatalyst. Herein, we report the mechanochemical synthesis of two polymorphs of a zeolitic imidazole framework, Co-doped zinc 2-trifluoromethyl-1H-imidazolate (Zn0.9Co0.1(CF3-Im)2). Time-resolved in situ X-ray diffraction studies of the mechanochemical formation revealed a direct conversion of starting materials to the products. Both polymorphs of Zn0.9Co0.1(CF3-Im)2 were pyrolyzed, yielding Co-N-F containing carbons, which are active toward electrochemical ORR. KW - Mechanochemistry KW - Metal-organic-frameworks KW - Nobel-metal free electrocatalysis PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546833 DO - https://doi.org/10.3389/fchem.2022.840758 SN - 2296-2646 VL - 10 IS - 840758 SP - 1 EP - 13 PB - Frontiers Media CY - Lausanne AN - OPUS4-54683 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heilmann, Maria A1 - Prinz, Carsten A1 - Bienert, Ralf A1 - Wendt, R. A1 - Kunkel, B. A1 - Radnik, Jörg A1 - Hoell, A. A1 - Wohlrab, S. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Emmerling, Franziska T1 - Size-Tunable Ni–Cu Core–Shell Nanoparticles—Structure, Composition, and Catalytic Activity for the Reverse Water–Gas Shift Reaction N2 - A facile and efficient methodology is described for the solvothermal synthesis of size-tunable, stable, and uniform NiCu core–shell nanoparticles (NPs) for application in catalysis. The diameter of the NPs is tuned in a range from 6 nm to 30 nm and to adjust the Ni:Cu ratio from 30:1 to 1:1. Furthermore, the influence of different reaction parameters on the final NPs is studied. The NPs are structurally characterized by a method combination of transmission electron microscopy, anomalous small-angle X-ray scattering, X-ray absorption fine structure, and X-ray photoelectron spectroscopy. Using these analytical methods, it is possible to elucidate a core–shell–shell structure of all particles and their chemical composition. In all cases, a depletion from the core to the shell is observed, with the core consisting of NiCu alloy, surrounded by an inner Ni-rich shell and an outer NiO shell. The SiO2-supported NiCu core–shell NPs show pronounced selectivity of >99% for CO in the catalytic reduction of CO2 to CO using hydrogen as reactant (reverse water–gas shift reaction) independent of size and Ni:Cu ratio. KW - Nanoparticles KW - Core-shell KW - Catalysis PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543606 DO - https://doi.org/10.1002/adem.202101308 SN - 1438-1656 SP - 1 EP - 13 PB - Wiley VCH AN - OPUS4-54360 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rodríguez-Sánchez, Noelia A1 - Bhattacharya, Biswajit A1 - Emmerling, Franziska A1 - Prinz, Carsten A1 - Prieto-Laria, P. A1 - Ruiz-Salvador, A.R. A1 - Ballesteros, M. T1 - Engineering a multivariate cobalt metal–organic framework for high photocatalytic activity: the impact of mixed ligands and metal incorporation in a visible light-driven heterogeneous photo-Fenton reaction for water treatment N2 - Metal–organic frameworks (MOFs) have attracted increasing attention for the removal of organic pollutants in wastewater via photocatalysis. Here, we design a multivariate modification of ZIF-9 to tune its electronic properties for use in visible light photocatalysis. A controllable synthesis of ZIF-9 and its multivariate forms with the incorporation of copper and the 2-imidazolecarboxaldehyde (ica) ligand was carried out. The materials are tested for the removal of the model dye methylene blue (MB) by a heterogeneous photo-Fenton-like reaction at neutral pH and room temperature. Cu-ZIF-9-ica (UPO-3) shows high photocatalytic activity under both visible and ultraviolet A (UVA) light, achieving 94% MB degradation in 45 min, compared to 65% MB degradation in 120 min using bare ZIF-9. The study revealed a first-order rate constant of 0.0475 min−1 for Cu-ZIF-9-ica compared to 0.0088 min−1 for ZIF-9 under visible light. The improvement of the catalyst was clearly attributed to the co-incorporation of Cu and the ica ligand in the MOF, which reduces the band gap, in agreement with DFT calculations. Reproducibility and recyclability tests proved that Cu-ZIF-9-ica can be used for at least 3 cycles without a significant loss of efficiency, making it a promising material for the study and application of wastewater treatment. KW - Metal-Organic Framework (MOF) KW - Heterogeneous photo-Fenton KW - ZIF-9 KW - Methylene Blue PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630797 DO - https://doi.org/10.1039/d4na00954a SN - 2516-0230 VL - 7 IS - 8 SP - 2255 EP - 2265 PB - Royal Society of Chemistry AN - OPUS4-63079 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Page, T.M. A1 - Nie, C. A1 - Neander, L. A1 - Povolotsky, T.L. A1 - Sahoo, A.K. A1 - Nickl, Philip A1 - Adler, J.M. A1 - Bawadkji, O. A1 - Radnik, Jörg A1 - Achazi, K. A1 - Ludwig, K. A1 - Lauster, D. A1 - Netz, R.R. A1 - Trimpert, J. A1 - Kaufer, B. A1 - Haag, R. A1 - Donskyi, Ievgen T1 - Functionalized Fullerene for Inhibition of SARS-CoV-2 Variants N2 - As virus outbreaks continue to pose a challenge, a nonspecific viral inhibitor can provide significant benefits, especially against respiratory viruses. Polyglycerol sulfates recently emerge as promising agents that mediate interactions between cells and viruses through electrostatics, leading to virus inhibition. Similarly, hydrophobic C60 fullerene can prevent virus infection via interactions with hydrophobic cavities of surface proteins. Here, two strategies are combined to inhibit infection of SARS-CoV-2 variants in vitro. Effective inhibitory concentrations in the millimolar range highlight the significance of bare fullerene’s hydrophobic moiety and electrostatic interactions of polysulfates with surface proteins of SARS-CoV-2. Furthermore, microscale thermophoresis measurements support that fullerene linear polyglycerol sulfates interact with the SARS-CoV-2 virus via its spike protein, and highlight importance of electrostatic interactions within it. All-atom molecular dynamics simulations reveal that the fullerene binding site is situated close to the receptor binding domain, within 4 nm of polyglycerol sulfate binding sites, feasibly allowing both portions of the material to interact simultaneously. KW - Covalent functionalization KW - Fullerene KW - SARS-CoV 2 KW - Sulfated materials KW - Virus inhibition PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568672 DO - https://doi.org/10.1002/smll.202206154 SN - 1613-6810 SP - 1 EP - 8 PB - Wiley VCH AN - OPUS4-56867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bawadkji, O. A1 - Cherri, M. A1 - Schäfer, A. A1 - Herziger, S. A1 - Nickl, Philip A1 - Achazi, K. A1 - Donskyi, Ievgen A1 - Adeli, M. A1 - Haag, R. T1 - One-pot covalent functionalization of 2D black phosphorus by anionic ring opening polymerization N2 - In this work, a one-pot approach for the covalent functionalization of few-layer black phosphorus (BP) by anionic ring opening polymerization of glycidol to obtain multifunctional BP-polyglycerol (BP-PG) with high amphiphilicity for near-infrared-responsive drug delivery and biocompatibility is reported. Straightforward synthesis in combination with exceptional biological and physicochemical properties designates functionalized BP-PG as a promising candidate for a broad range of biomedical applications. KW - 2D nanomaterial KW - Amphiphilicity KW - Black phosphorus KW - Hyperbranched KW - Polyglycerol KW - Water dispersibility PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568833 DO - https://doi.org/10.1002/admi.202201245 SN - 2196-7350 VL - 9 SP - 1 EP - 8 PB - Wiley-VCH CY - Weinheim AN - OPUS4-56883 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Knigge, Xenia A1 - Radnik, Jörg T1 - 1,3-Dimethyl-imidazolium dimethyl phosphate ([MMIM]+[DMP]−) analyzed by XPS and HAXPES N2 - The ionic liquid 1,3-dimethyl-imidazolium-dimethylphosphate ([MMIM]+[DMP]−) was analyzed using (hard) x-ray photoelectron spectroscopy. Here, XPS and HAXPES spectra are shown in comparison. For the acquisition of the XPS spectra, monochromatic Al Kα radiation at 1486.6 eV was used, while for the acquisition of the HAXPES spectra, monochromatic Cr Kα radiation at 5414.8 eV was applied. Here, survey scans and high-resolution spectra of P 2p, P 2s, C 1s, O 1s, and N 1s for both methods and P 1s, P KL2,3L2,3, and P KL1L2,3 for HAXPES are shown. KW - C7H15N2O4P KW - [MMIM]+[DMP]− KW - Lonic liquid KW - Hard x-ray photoelectron spectroscopy KW - HAXPES KW - XPS PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-571604 DO - https://doi.org/10.1116/6.0002297 VL - 30 IS - 1 SP - 1 EP - 20 PB - AIP Publishing AN - OPUS4-57160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chen, Z. A1 - Perez, J. P. H. A1 - Smales, Glen Jacob A1 - Blukis, R. A1 - Pauw, Brian Richard A1 - Stammeier, J. A. A1 - Radnik, Jörg A1 - Smith, A. J. A1 - Benning, L. G. T1 - Impact of organic phosphates on the structure and composition of short-range ordered iron nanophases N2 - Organic phosphates (OP) are important nutrient components for living cells in natural environments, where they readily interact with ubiquitous iron phases such as hydrous ferric oxide, ferrihydrite (FHY). FHY partakes in many key bio(geo)chemical reactions including iron-mediated carbon storage in soils, or iron-storage in living organisms. However, it is still unknown how OP affects the formation, structure and properties of FHY. Here, we document how β-glycerophosphate (GP), a model OP ligand, affects the structure and properties of GP–FHY nanoparticles synthesized by coprecipitation at variable nominal molar P/Fe ratios (0.01 to 0.5). All GP–FHY precipitates were characterized by a maximum solid P/Fe ratio of 0.22, irrespective of the nominal P/Fe ratio. With increasing nominal P/Fe ratio, the specific surface area of the GP–FHY precipitates decreased sharply from 290 to 3 m2 g−1, accompanied by the collapse of their pore structure. The Fe–P local bonding environment gradually transitioned from a bidentate binuclear geometry at low P/Fe ratios to monodentate mononuclear geometry at high P/Fe ratios. This transition was accompanied by a decrease in coordination number of edge-sharing Fe polyhedra, and the loss of the corner-sharing Fe polyhedra. We show that Fe(III) polymerization is impeded by GP, and that the GP–FHY structure is highly dependent on the P/Fe ratio. We discuss the role that natural OP-bearing Fe(III) nanophases have in biogeochemical reactions between Fe–P and C species in aquatic systems. KW - Organic phosphates KW - Iron nanophases KW - Scattering KW - Diffraction KW - Nanomaterials KW - Coprecipitation KW - Carbon storage PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-599399 DO - https://doi.org/10.1039/d3na01045g SN - 2516-0230 SP - 1 EP - 13 PB - Royal Society of Chemistry (RSC) CY - Cambridge AN - OPUS4-59939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bennet, Francesca A1 - Opitz, R. A1 - Ghoreishi, N. A1 - Plate, K. A1 - Barnes, J.-P. A1 - Bellew, A. A1 - Bellu, A. A1 - Ceccone, G. A1 - de Vito, E. A1 - Delcorte, A. A1 - Franquet, A. A1 - Fumageli, F. A1 - Gilliland, D. A1 - Jungnickel, H. A1 - Lee, T.G. A1 - Poleunis, C. A1 - Rading, D. A1 - Shon, H.K. A1 - Spampinato, V. A1 - Son, J.G. A1 - Wang, F. A1 - Wang, Y.-C. A. A1 - Zhao, Y. A1 - Roloff, A. A1 - Tentschert, J. A1 - Radnik, Jörg T1 - VAMAS TWA2 interlaboratory comparison: Surface analysis of TiO2 nanoparticles using ToF-SIMS N2 - Due to the extremely high specific surface area of nanoparticles and corresponding potential for adsorption, the results of surface analysis can be highly dependent on the history of the particles, particularly regarding sample preparation and storage. The sample preparation method has, therefore, the potential to have a significant influence on the results. This report describes an interlaboratory comparison (ILC) with the aim of assessing which sample preparation methods for ToF-SIMS analysis of nanoparticles provided the most intra- and interlaboratory consistency and the least amount of sample contamination. The BAM reference material BAM-P110 (TiO2 nanoparticles with a mean Feret diameter of 19 nm) was used as a sample representing typical nanoparticles. A total of 11 participants returned ToF-SIMS data,in positive and (optionally) negative polarity, using sample preparation methods of “stick-and-go” as well as optionally “drop-dry” and “spin-coat.” The results showed that the largest sources of variation within the entire data set were caused by adventitious hydrocarbon contamination or insufficient sample coverage, with the spin-coating protocol applied in this ILC showing a tendency toward insufficient sample coverage; the sample preparation method or the participant had a lesser influence on results. KW - Secondary Ion Mass Spectrometry KW - VMAAS KW - Titania KW - Interlaboratory comparison KW - Reproducibility PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582290 DO - https://doi.org/10.1116/6.0002814 SN - 0734-2101 VL - 41 IS - 5 SP - 053210-1 EP - 053210-13 PB - AIP (American Institute of Physics) AN - OPUS4-58229 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hirahara, Kenta A1 - Bonse, Jörn A1 - Krüger, Jörg A1 - Weise, Matthias A1 - Ermilova, Elena A1 - Schusterbauer, Robert A1 - Unterreiner, Andreas-Neil A1 - Hertwig, Andreas T1 - A multi-method study of femtosecond laser modification and ablation of amorphous hydrogenated carbon coatings N2 - e present a study on femtosecond laser treatment of amorphous hydrogen-containing carbon coatings (a-C:H). The coatings were deposited on silicon wafers by a plasma-assisted chemical vapour deposition (PA-CVD), resulting in two different types of material with distinct properties (referred to as “absorbing” and “semi-transparent” coatings in the following). The samples were laser-treated with single fs-laser pulses (800 nm center wavelength, 35 fs pulse duration) in the ablative regime. Through a multi-method approach using topometry, Raman spectroscopy, and spectroscopic imaging ellipsometry, we can identify zones and thresholds of diferent fuence dependent efects and have access to the local dielectric function. The two coating materials react signifcantly diferent upon laser treatment. We determined the (non-ablative) modifcation threshold fuence for the absorbing coating as 3.6 × 10−2 Jcm−2 and its ablation threshold as 0.22 Jcm−2. The semi-transparent coating does not show such a low-fuence modifcation but exhibits a characteristic interference-based intra-flm ablation mechanism with two distinguishable ablation thresholds at 0.25 and 0.28 Jcm−2, respectively. The combination of tailored layer materials and correlative imaging spectroscopic methods delivers new insights into the behaviour of materials when treated with ultrashort-pulse laser radiation KW - Amorphous Hydrogenated Carbon Coatings KW - Correlative Imaging Measurement Techniques KW - Hybrid Metrology KW - Imaging Spectroscopy KW - Spectroscopic Ellipsometry KW - Ultra-short Pulse Laser Materials Processing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-617829 DO - https://doi.org/10.1007/s00339-024-07980-z VL - 130 IS - 12 SP - 1 EP - 17 PB - Springer Science and Business Media LLC AN - OPUS4-61782 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Junge, Florian A1 - Wittwer, Philipp A1 - Sommerfeld, Thomas A1 - Gehrenkemper, Lennart A1 - Zoister, Christian A1 - Nickl, Philip A1 - Koch, Matthias A1 - Meermann, Björn A1 - Haag, Rainer T1 - Adsorber Charge Dominates over Hydrophobic or Fluorophilic Functionalization in Influencing Adsorption of PFCA onto Polystyrene Resins N2 - A systematic series of industrial-relevant polystyrene-based anion exchange resins that are functionalized with hydro- or fluorocarbon chains are compared regarding their adsorption behavior toward perfluorocarboxylic acids (PFCA) in respect to their charge, chain length, and type of chain. The results clearly show the dominance of electrostatic interactions in the adsorption process as uncharged adsorber materials showed no adsorption at all. In contrast, the charged adsorber materials showed in general a PFCA removal of 80% to 30% over the experiment depending on effluent fraction. Unexpectedly, for perfluorobutanoic acid (PFBA) the highest removal rate is found with consistently >90%. Despite observing significant benefits in the adsorption of PFCA for fluoroalkylated adsorbers in comparison to their non-fluorinated counterparts, this effect of fluoroalkylation is comparatively small and can not be clearly attributed to fluorophilic interactions between the fluoroalkyl chains. These findings help clarifying that the introduction of fluorocarbon moieties in adsorber materials is not necessary in order to remove fluorocarbon molecules from the environment. KW - PFAS KW - Remediation KW - Adsorption KW - Fluorophilic interactions PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601883 DO - https://doi.org/10.1002/admi.202400199 SN - 2196-7350 SP - 1 EP - 10 PB - John Wiley & Sons CY - Hoboken, New Jersey, USA AN - OPUS4-60188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nguyen, H. G. A1 - Toman, B. A1 - van Zee, R. A1 - Prinz, Carsten A1 - Thommes, M. A1 - Ahmad, R. A1 - Kiska, D. A1 - Salinger, J. A1 - Walton, I. A1 - Walton, K. A1 - Broom, D. A1 - Benham, M. A1 - Ansari, H. A1 - Pini, R. A1 - Petit, C. A1 - Adolphs, J. A1 - Schreiber, A. A1 - Shigeoka, T. A1 - Konishi, Y. A1 - Nakai, K. A1 - Henninger, M. A1 - Petrzik, T. A1 - Kececi, C. A1 - Martis, V. A1 - Paschke, T. A1 - Mangano, E. A1 - Brandani, S. T1 - Reference isotherms for water vapor sorption on nanoporous carbon: results of an interlaboratory study N2 - This paper reports the results of an international interlaboratory study sponsored by the Versailles Project on Advanced Materials and Standards (VAMAS) and led by the National Institute of Standards and Technology (NIST) on the measurement of water vapor sorption isotherms at 25 °C on a pelletized nanoporous carbon (BAM-P109, a certified reference material). Thirteen laboratories participated in the study and contributed nine pure water vapor isotherms and four relative humidity isotherms, using nitrogen as the carrier gas. From these data, reference isotherms, along with the 95% uncertainty interval (Uk=2), were determined and are reported in a tabular format. KW - BAM-P109 KW - Interlaboratory study KW - Nanoporous carbon KW - Reference isotherm KW - VAMAS PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-576560 DO - https://doi.org/10.1007/s10450-023-00383-1 SN - 0929-5607 SP - 1 EP - 12 PB - Springer CY - Heidelberg AN - OPUS4-57656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baer, Wolfram A1 - Wossidlo, Peter T1 - Validation of a low blow specimen technique for R-curve determination using a drop tower N2 - Fracture mechanics based component design requires appropriate fracture mechanics toughness data with respect to both, loading rate as well as test temperature. Taking high-rate loading into account such as with accidental scenarios, different standards such as ASTM E 1820 or BS 7448-3 provide some information on dynamic fracture mechanics testing. Nevertheless, the designations differ so that a validation of the own material specific test method used for dynamic R-curve determination is mandatory. In order to address this for ductile cast iron materials an experimental method for the reliable determination of dynamic J-integral crack resistance curves at -40 °C following the multiple specimen approach has been established and validated. The experimental concept offers some additional valuable features. Single values of dynamic crack initiation toughness can be determined using a single specimen technique based on crack sensors. Furthermore, an experimentally independent method is provided according to which CTOD δ5 R-curves can be established. The focus of the present paper is on the validation of the experimental low blow technique using a drop tower test system. A drop tower test system was developed and set up to perform low blow tests at temperatures down to -40 °C. The system allows for a variation of the impact mass and height and was optimized for testing of ductile cast iron at stress intensity rates from approximately 5∙10⁴ to 3∙10⁵ MPa√ms⁻¹. This range of loading rate is characteristic for instance with crash scenarios of heavy sectioned DCI casks for radioactive materials. In order to address characteristic challenges of impact tests (test duration of microseconds up to milliseconds, inertial effects, signal oscillations), an appropriate full bridge strain gage method for the measurement of force directly on the specimen as well as a non-contact measurement of load line displacement using an optical extensometer have been developed and validated. The low blow test requires either to prevent bouncing strikes of the hammer by using the stop block technique or to catch the hammer after its first strike. Both options are not part of the experimental concept and setup which have been realized here. The paper describes investigations which have been performed in order to make sure that bouncing strikes of the hammer do not cause additional crack extension in the specimen. This is necessary to ensure a unique relation between the work done and the achieved crack extension. The investigations covered the analysis of limit loads of the specimen with respect to the measured force. The measured stiffness of the specimen was assessed and signals of crack sensors were analyzed. Furthermore, an analysis of the mechanical behavior of the loading system and the specimen by optical observation was performed. Corresponding results are discussed in the paper. It had finally been proven that additional crack extension in the specimen due to bouncing strikes of the hammer is not to be expected under the given conditions of test setup, material and loading. It can be seen as a major experimental advantage that the striker does not have to be catched after the low blow test. T2 - XXIV Italian Group of Fracture Conference CY - Urbino, Italy DA - 01.03.2017 KW - Dynamic fracture mechanics KW - R-curve KW - Low blow KW - Ductile cast iron PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-437686 DO - https://doi.org/10.1016/j.prostr.2017.04.005 SN - 2452-3216 VL - 3 SP - 25 EP - 32 AN - OPUS4-43768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baensch, Franziska A1 - Hussels, Maria-Teresa A1 - Chruscicki, Sebastian A1 - Baer, Wolfram A1 - Wossidlo, Peter A1 - Homann, Tobias A1 - Prager, Jens A1 - Schmidt, Dirk A1 - Weltschev, Margit A1 - Habib, Abdel Karim T1 - BAM-Projekt AGIFAMOR – Zustandsüberwachung von Rohrleitungen N2 - Rohrleitungssysteme sind aufgrund ihrer Funktion und Ausdehnung für den Betrieb, die Verfügbarkeit und die Sicherheit von Industrieanlagen von besonderer Bedeutung. Die bisher in definierten Intervallen durchgeführten, wiederkehrenden Prüfungen zur Sicherstellung leckagefreier Rohrleitungen sind kostenintensiv und mit einem erhöhten Aufwand verbunden. Mit dem interdisziplinären Forschungsprojekt AGIFAMOR (Ageing Infrastructures – Akustisches Monitoring von Rohrleitungen) arbeitet die BAM an der Entwicklung und Erprobung einer örtlich und zeitlich kontinuierlichen Zustandsüberwachung von Rohrleitungen basierend auf einem faseroptischen akustischen Messsystem, welches einen vergleichsweise geringen Installationsaufwand der Sensoren erfordert. Mit diesem Verfahren sollen vor allem betriebsbedingte Schädigungen infolge von Korrosion sowie daraus entstehende Pittings oder Risse erkannt und damit Leckagen verhindert werden. Im Rahmen einer Machbarkeitsstudie zum Teilaspekt „Detektion von Risswachstum“ wurde ein 2,5 m langes, definiert vorgekerbtes Stahlrohr mit der faseroptischen Sensorik (FOS) ausgestattet und quasistatisch unter 4-Punkt-Biegung belastet. Mit fortschreitender Belastung wächst, ausgehend vom vorhandenen Außenumfangskerb, ein Riss im Stahlrohr bis zum Erreichen der Leckage – in der Praxis ein gefährliches Schadensszenario. Parallel zur FOS erfolgten Messungen mit Schallemissionssensoren, Beschleunigungssensoren und Potentialsonden, deren Ergebnisse die Interpretation der FOS-Messergebnisse unterstützen sollen. T2 - 21. Kolloquium Schallemission CY - Fulda, Germany DA - 09.03.2017 KW - Beschleunigungssensoren KW - Faseroptische Sensorik KW - Schallemission KW - Monitoring KW - Rohrleitung PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-401811 SN - 978-3-940283-82-5 VL - DGZfP-BB 159 SP - Vortrag 17, 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-40181 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ha, Q. L. M. A1 - Armbruster, U. A1 - Atia, Hanan A1 - Lund, H. A1 - Agostini, G. A1 - Radnik, Jörg A1 - Vuong, H. T. A1 - Martin, A. T1 - Development of active and stable low nickel content catalysts for dry reforming of methane N2 - Methane dry reforming (DRM) was investigated over highly active Ni catalysts with low metal content (2.5wt%) supported on Mg-Al mixed oxide. The aim was to minimize carbon Deposition and metal sites agglomeration on the working catalyst which are known to cause catalyst deactivation. The solids were characterized using N2 adsorption, X-ray diffraction, temperature-programmed reduction, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results showed that MgO-Al2O3 solid solution phases are obtained when calcining Mg-Al hydrotalcite precursor in the temperature range of 550–800 °C. Such phases contribute to the high activity of catalysts with low Ni content even at low temperature (500 °C). Modifying the catalyst preparation with citric acid significantly slows the coking rate and reduces the size of large octahedrally coordinated NiO-like domains, which may easily agglomerate on the surface during DRM. The most effective Ni catalyst shows a stable DRM course over 60 h at high weight hourly space velocity with very low coke deposition. This is a promising result for considering such catalyst systems for further development of an industrial DRM technology. KW - Dry reforming of methane KW - Carbon dioxide KW - Ni PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-402904 DO - https://doi.org/10.3390/catal7050157 SN - 2073-4344 VL - 7 IS - 5 SP - 157, 1 EP - 157, 17 PB - MDPI AN - OPUS4-40290 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abbas, F. A1 - Donskyi, Ievgen A1 - Gholami, M. A1 - Ziem, B. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Böttcher, C. A1 - Rabe, J. A1 - Haag, R. A1 - Adeli, M. T1 - Controlled covalent functionalization of thermally reduced graphene oxide to generate defined bifunctional 2D nanomaterials N2 - A controlled, reproducible, gram-scale method is reported for the covalent functionalization of graphene Sheets by a one-pot nitrene [2+1] cycloaddition reaction under mild conditions. The reaction between commercially available 2,4,6-trichloro-1,3,5-triazine and sodium azide with thermally reduced graphene oxide (TRGO) results in defined dichlorotriazine-functionalized sheets. The different reactivities of the chlorine substituents on the functionalized graphene allow stepwise post-modification by manipulating the temperature. This new method provides unique access to defined bifunctional 2D nanomaterials, as exemplified by chiral surfaces and multifunctional hybrid architectures. KW - Graphene oxide KW - Bifunctional 2D nanomaterials KW - XPS KW - NEXAFS KW - AFM PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-394789 DO - https://doi.org/10.1002/ange.201612422 SN - 1433-7851 VL - 56 IS - 10 SP - 2675 EP - 2679 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-39478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seeburg, Dominik A1 - Liu, Dongjing A1 - Radnik, Jörg A1 - Atia, Hanan A1 - Pohl, Marga-Martina A1 - Schneider, Matthias A1 - Martin, Andreas A1 - Wohlrab, Sebastian T1 - Structural changes of highly active Pd/MeOx (Me = Fe, Co, Ni) during catalytic methane combustion N2 - Fe2O3, Co3O4 and NiO nanoparticles were prepared via a citrate method and further functionalized with Pd by impregnation. The pure oxides as well as Pd/Fe2O3, Pd/Co3O4, and Pd/NiO (1, 5 and 10 wt % Pd) were employed for catalytic methane combustion under methane lean (1 vol %)/oxygen rich (18 vol %, balanced with nitrogen) conditions. Already, the pure metal oxides showed a high catalytic activity leading to complete conversion temperature of T100 ≤ 500 °C. H2-TPR (Temperature-programmed reduction) experiments revealed that Pd-functionalized metal oxides exhibited enhanced redox activity compared to the pure oxides leading to improved catalytic combustion activity at lower temperatures. At a loading of 1 wt % Pd, 1Pd/Co3O4 (T100 = 360 °C) outperforms 1Pd/Fe2O3 (T100 = 410 °C) as well as 1Pd/NiO (T100 = 380 °C). At a loading of 10 wt % Pd, T100 could only be slightly reduced in all cases. 1Pd/Co3O4 and 1Pd/NiO show reasonable stability over 70 h on stream at T100. XPS (X-ray photoelectron spectroscopy) and STEM (Scanning transmission electron microscopy) investigations revealed strong interactions between Pd and NiO as well as Co3O4, respectively, leading to dynamic transformations and reoxidation of Pd due to solid state reactions, which leads to the high long-term stability. KW - Methane total oxidation KW - Methane removal KW - Carbon dioxide KW - X-ray photoelectron spectroscopy PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-439412 DO - https://doi.org/10.3390/catal8020042 SN - 2073-4344 VL - 8 IS - 2 SP - Article 42, 1 EP - 13 PB - MDPI AN - OPUS4-43941 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Beiranvand, Z. A1 - Kakanejadifard, A. A1 - Donskyi, Ievgen A1 - Faghani, A. A1 - Tu, Z. A1 - Lippitz, Andreas A1 - Sasanpour, P. A1 - Maschietto, F. A1 - Paulus, B. A1 - Haag, R. A1 - Adeli, M. T1 - Functionalization of fullerene at room temperature: toward new carbon vectors with improved physicochemical properties N2 - In this work, fullerene has been functionalized with cyanuric Chloride at room temperature by a nitrene mediated [2 + 1] cycloaddition reaction. The adduct after functionalization is inherently in the form of azafulleroid and shows broad UV absorption in the wavelength range of 200–800 nm, as well as photothermal conversion and fluorescence with a high quantum yield. KW - Functionalization of fullerenes KW - XPS KW - NEXAFS PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-387076 DO - https://doi.org/10.1039/c6ra23419d SN - 2046-2069 VL - 6 IS - 114 SP - 112771 EP - 112775 PB - Royal Society of Chemistry (RSC) AN - OPUS4-38707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Broicher, Cornelia A1 - Zeng, F. A1 - Pfänder, N. A1 - Frisch, M. A1 - Bisswanger, T. A1 - Radnik, Jörg A1 - Stockmann, Jörg M. A1 - Palkovits, S. A1 - Beine, A. K. A1 - Palkovits, R. T1 - Iron and Manganese Containing Multi-Walled Carbon Nanotubes as Electrocatalysts for the Oxygen Evolution Reaction - Unravelling Influences on Activity and Stability N2 - Hydrogen economy is a central aspect of future energy supply, as hydrogen can be used as energy storage and fuel. In order tomake water electrolysis efficient, the limiting oxygen evolution reaction (OER) needs to be optimized. Therefore, C-based composite materials containing earth-abundant Fe and Mn were synthesized, characterized and tested in the OER. For pyrolysis temperatures above 700°C N-rich multi-walled carbon nanotubes (MWCNT) are obtained. Inside the tubes Fe3C particles are formed, Fe and Mn oxides are incorporated in the carbon matrix and metal spinel nanoparticles cover the outer surface. The best catalyst prepared at 800°C achieves a low overpotential of 389 mV (at 10 mA/cm2) and high stability (22.6 h). From electrochemical measurements and characterization it can be concluded that the high activity is mainly provided by MWCNT, Fe3C and the metal oxides in the conductive carbon matrix. The metal spinel nanoparticles in contrast protect the MWCNT from oxidation and thereby contribute to the high stability. KW - Oxygen Evolution Reaction KW - Carbon Nanotubes KW - Stability PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513955 DO - https://doi.org/10.1002/cctc.202000944 VL - 12 IS - 21 SP - 1 EP - 8 PB - Wiley Online Libary AN - OPUS4-51395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stockmann, Jörg M. A1 - Radnik, Jörg A1 - Bütefisch, S. A1 - Busch, I. A1 - Weimann, T. A1 - Passiu, C. A1 - Rossi, A. A1 - Unger, Wolfgang T1 - A new test specimen for the determination of the field of view of small-area X-ray photoelectron spectrometers N2 - Small-area/spot photoelectron spectroscopy (SAXPS) is a powerful tool for the investigation of small surface features like microstructures of electronic devices, sensors or other functional surfaces, and so forth. For evaluating the quality of such microstructures, it is often crucial to know whether a small signal in a spectrum is an unwanted contamination of the field of view (FoV), defined by the instrument settings, or it originated from outside. To address this issue, the d80/20 parameter of a line scan across a chemical edge is often used. However, the typical d80/20 parameter does not give information on contributions from the long tails of the X-ray beam intensity distribution or the electron-optical system as defined by apertures. In the VAMAS TWA2 A22 project “Applying planar, patterned, multi-metallic samples to assess the impact of analysis area in surface-chemical analysis,” new test specimen was developed and tested. The here presented testing material consists of a silicon wafer substrate with an Au-film and embedded Cr circular and square spots with decreasing dimensions from 200 μm down to 5 μm. The spot sizes are traceable to the length unit due to size measurements with a metrological SEM. For the evaluation of the FoV, we determined the Au4f intensities measured with the center of the FoV aligned with the center of the spot and normalized to the Au4f intensity determined on the Au-film. With this test specimen, it was possible to characterize, as an example, the FoV of a Kratos AXIS Ultra DLD XPS instrument. T2 - ECASIA 2019 CY - Dresden, Germany DA - 15.09.2019 KW - Field of view KW - Reference material KW - Selected area XPS KW - Small-area XPS KW - Small-spot XPS PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509902 DO - https://doi.org/10.1002/sia.6831 SN - 1096-9918 VL - 52 IS - 12 SP - 890 EP - 894 PB - John Wiley & Sons Ltd AN - OPUS4-50990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Broichert, C. A1 - Klingenhof, M. A1 - Frisch, M. A1 - Dresp, S. A1 - Kubo, N.M. A1 - Artz, J. A1 - Radnik, Jörg A1 - Palkovits, S. A1 - Beine, A.K. A1 - Strasser, P. A1 - Palkovits, R. T1 - Particle size-controlled synthesis of highperformance MnCo-based materials for alkaline OER at fluctuating potentials N2 - For the large-scale generation of hydrogen via water electrolysis the design of long term stable and active catalysts for the oxygen evolution reaction (OER) remains a key challenge. Most catalysts suffer from severe structural corrosion that becomes even more pronounced at fluctuating potentials. Herein, MnCo based cubic particles were prepared via a hydrothermal approach, in which the edge length of the micron-sized particles can be controlled by changing the pH value of the precursor solution. The cubes are composed of varying amounts of MnCo2O4, CoCO3 and a mixed (Mn/Co)CO3 phase. Structure–activity relationships were deduced revealing a volcano-type behavior for the intrinsic OER activity and fraction of spinel oxide phase. A low overpotential of 0.37 V at 10 mA cm−2 and a stability of more than 25 h was achieved in 1.0 M KOH using a rotating disc electrode (RDE) setup. The best performing catalyst material was successfully tested under dynamic process conditions for 9.5 h and shows a superior catalytic activity as anode for the Overall water splitting in an electrolyser setup in 1.0 M KOH at 333 K compared to a reference NiCo-spinel catalyst. KW - Water electrolysis KW - Oxygen evolution reaction KW - Structure activity relationships PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-536050 DO - https://doi.org/10.1039/d1cy00905b SN - 2044-4753 VL - 11 IS - 12 SP - 7278 EP - 7286 PB - Royal Society of Chemistry AN - OPUS4-53605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -