TY - JOUR A1 - Lin, R. A1 - Li, X. A1 - Krajnc, A. A1 - Li, Z. A1 - Li, M. A1 - Wang, W. A1 - Zhuang, L. A1 - Smart, S. A1 - Zhu, Z. A1 - Appadoo, D. A1 - Harmer, J. R. A1 - Wang, Z. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Beyer, S. A1 - Wang, L. A1 - Mali, G. A1 - Bennett, T. D. A1 - Chen, V. A1 - Hou, J. T1 - Mechanochemically Synthesised Flexible Electrodes Based on Bimetallic Metal–Organic Framework Glasses for the Oxygen Evolution Reaction JF - Angewandte Chemie Int. Ed. N2 - The melting behaviour of metal–organic frameworks (MOFs) has aroused significant research interest in the areas of materials science, condensed matter physics and chemical engineering. This work first introduces a novel method to fabricate a bimetallic MOF glass, through meltquenching of the cobalt-based zeolitic imidazolate Framework (ZIF) [ZIF-62(Co)] with an adsorbed ferric coordination complex. The high-temperature chemically reactive ZIF-62-(Co) liquid facilitates the formation of coordinative bonds between Fe and imidazolate ligands, incorporating Fe nodes into the framework after quenching. The resultant Co–Fe bimetallic MOF glass therefore shows a significantly enhanced oxygen evolution reaction performance. The novel bimetallic MOF glass, when combined with the facile and scalable mechanochemical synthesis technique for both discrete powders and surface coatings on flexible substrates, enables significant opportunities for catalytic device Assembly KW - Electrodes KW - MOF KW - OER KW - XANES KW - XAS KW - Bimetallic frameworks PY - 2022 DO - https://doi.org/10.1002/anie.202112880 VL - 61 IS - 4 SP - e202112880 PB - Wiley AN - OPUS4-54018 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cakir, Cafer Tufan T1 - Unravelling the depths of complex alloys with grazing exit XANES N2 - High entropy alloys (HEAs) are considered as a new class of alloys containing at least 5 elements with concentrations between 5 and 35 atomic percent. There has been a growing interest in HEAs in the material research field in recent years. Due to their adjustable composition, which enables the modifications of mechanical properties (such as hardness, strength and ductility etc) and their stability at high temperatures, HEAs have been the focus of various studies. Especially the corrosion behavior of HEAs has been a wide research interest. Since the grazing exit X-ray fluorescence (GEXRF) offers a non-destructive way to collect notable information regarding the high temperature oxidation, we consider it as a useful method to investigate how HEAs behave in corrosive environments. The main idea of grazing geometry is to enhance the fluorescence signal of the surface. This enables highly sensitive surface analyses of thin protective film on surface in sub-micrometer scale. Position-sensitive area detectors provide information regarding the signal emitted from the sample as a function of emission angle and thus allow depth-sensitive analysis. Furthermore, the data collected from samples of an incidence energy which lays within a specific energy range provides XANES data to determine oxidation states. Moreover, since GEXRF profiles can also be simulated through physical models (Urbach 1999), they enable us to determine the layer thickness of a given sample in a non-destructive way. In this contribution, we present the preliminary results of a conceptual study regarding layer properties of CrCoNi medium entropy alloy. The successful implementation of such methodological concept will pave the way for the investigation of more complex alloys with multiple layers, which is planned for the later phases of the project. T2 - Denver X-Ray Conference DXC 2021 CY - Online meeting DA - 02.08.2021 KW - GEXRF KW - High entropy alloys KW - XANES KW - Grazing exit KW - XAS PY - 2021 AN - OPUS4-54027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cakir, Cafer Tufan T1 - Unrevealing the depths of compositionally complex alloys with grazing exit XANES N2 - High entropy alloys (HEAs) are considered as a new class of alloys containing at least 5 elements with concentrations between 5 and 35 atomic percent. There has been a growing interest in HEAs in the material research field in recent years. Due to their adjustable composition, which enables the modifications of mechanical properties (such as hardness, strength and ductility etc) and their stability at high temperatures, HEAs have been the focus of various studies. Especially the corrosion behavior of HEAs has been a wide research interest. Since the grazing exit X-ray fluorescence (GEXRF) offers a non-destructive way to collect notable information regarding the high temperature oxidation, we consider it as a useful method to investigate how HEAs behave in corrosive environments. The main idea of grazing geometry is to enhance the fluorescence signal of the surface. This enables highly sensitive surface analyses of thin protective film on surface in sub-micrometer scale. Position-sensitive area detectors provide information regarding the signal emitted from the sample as a function of emission angle and thus allow depth-sensitive analysis. Furthermore, the data collected from samples of an incidence energy which lays within a specific energy range provides XANES data to determine oxidation states. Moreover, since GEXRF profiles can also be simulated through physical models (Urbach 1999), they enable us to determine the layer thickness of a given sample in a non-destructive way. In this contribution, we present the preliminary results of a conceptual study regarding layer properties of CrCoNi medium entropy alloy. The successful implementation of such methodological concept will pave the way for the investigation of more complex alloys with multiple layers, which is planned for the later phases of the project. T2 - XAFS 2021, The 18th International XAFS Conference CY - Online meeting DA - 02.08.2021 KW - GEXRF KW - High entropy alloys KW - XANES KW - Grazing exit KW - XAS PY - 2021 AN - OPUS4-54028 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wurzler, Nina A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Kunte, Hans-Jörg A1 - Özcan Sandikcioglu, Özlem T1 - Chemical interaction mechanisms of metal reducing bacteria on steel surfaces N2 - Metal reducing bacteria (MRB) are able to utilize various materials such as iron, uranium and manganese as well as many organic compounds as electron acceptors. This process leads to the conversion of Fe(III) containing passive film species to soluble Fe(II) oxides and hydroxides. The reduction process triggers the acceleration of general and local corrosion processes. Electron transfer mechanisms are not yet fully understood. In literature it has been controversially discussed to which extend secreted electron shuttles contribute to the extracellular electron transfer (EET). To understand the chemical and electrochemical interaction mechanisms of MRB with steel surfaces this project combines a variety of in-situ techniques. The changes in oxide chemistry on Fe/steel surfaces in the presence of biomolecules and MRB are under investigation using a newly designed electrochemical cell for in situ XANES (x-ray absorption near edge structure) spectroscopy. Electrochemical quartz crystal microbalance (eQCM) studies support the spectroscopic investigations to gain information about the kinetics of attachment processes and changes in biofilm viscosity. The biofilm structure and composition as well as cell viability are investigated by complementary ex situ spectroscopic and microscopic analysis. Combining spectroscopic techniques and eQCM data with electrochemical measurements, biological processes and the resulting degradation of steel surfaces can be observed in a non-destructive manner. Selecting model systems and a defined biological medium allows the determination of individual effects of diverse surface and environmental parameters. The fundamental understanding of bacterial attachment mechanisms and initial steps of biofilm formation will contribute to the development of new antifouling strategies. T2 - 12th International Conference on Biology and Synchrotron Radiation CY - San Francisco, CA, USA DA - 21.08.2016 KW - Microbially influenced corrosion (MIC) KW - Metal reducing bacteria KW - XANES KW - Electrochemistry PY - 2016 AN - OPUS4-37238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kabelitz, Anke A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Radtke, Martin A1 - Bienert, Ralf A1 - Schulz, K. A1 - Kraehnert, R. A1 - Emmerling, Franziska T1 - Time-resolved studies on the formation of maghemite nanoparticles combining fast-XANES and SAXS N2 - Iron oxide nanoparticles find application in different areas like sensing, magnetic storage media, and biomedicine, due to their magnetic properties and environment-friendliness. In the present contribution, we report on the in situ investigation of an iron oxide nanoparticle synthesis by coupled X-ray absorption near-edge structure (XANES) and small-angle X-ray scattering (SAXS). The combination provides simultaneously information about the size of particles (SAXS) and on the oxidation state and the local structure of the iron atoms (XANES). The co-precipitation synthesis was exemplary studied, using a stabilization agent to decelerate the fast precipitation of the iron oxides. This allows to detect intermediates in situ. The measurements were performed using a custom-made acoustic levitator as sample holder. From the data, a mechanism was derived indicating different phases of particle Formation and oxidation state changes. T2 - The European Materials Research Society-Spring Meeting 2016 CY - Lille, France DA - 01.05.2016 KW - Iron oxide nanoparticles KW - SAXS KW - XANES KW - Time-resolved PY - 2016 AN - OPUS4-36351 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wurzler, Nina A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Kunte, Hans-Jörg A1 - Özcan Sandikcioglu, Özlem T1 - Investigation of the mechanisms of microbially induced corrosion on Fe/steel surfaces N2 - The role of metal reducing bacteria (MRB) in corrosion is being controversially discussed in the literature. They can utilize metals including iron, uranium and manganese as well as many organic compounds as electron acceptors. The reduction of Fe(III) compounds to soluble Fe(II) species leads to the destruction of passive films on steel, resulting in acceleration of general and local corrosion processes. Recent research shows that the secretion of electron shuttles like riboflavins also contribute to the extracellular electron transfer (EET). The aim of this project is to understand the chemical and electrochemical interaction mechanisms of MRB with steel surfaces by means of combined in situ techniques. An electrochemical XANES (x-ray absorption near edge spectroscopy) cell has been designed to study the changes of passive film chemistry in the presence of biomolecules and MRB. Electrochemical quartz crystal microbalance (eQCM) is used for studying the kinetics of bacterial cell attachment and diffusion of biomolecules in model biofilms. In situ investigations are complemented by ex situ spectroscopic and microscopic analysis to investigate the biofilm structure, composition and cell viability. Via the combination of electrochemical methods with spectroscopic techniques and QCM we are able to follow biological processes and resulting degradation of steel surfaces in a non-destructive manner. The selection of model systems and a defined biological medium allows the identification of the effects of individual surface and environmental parameters. The fundamental understanding of bacterial attachment mechanisms and initial steps of biofilm formation will contribute to the development of new antifouling strategies. T2 - Electrochemistry 2016 CY - Goslar, Germany DA - 26.09.2016 KW - MIC KW - Microbiologically influenced corrosion KW - XANES KW - Electrochemistry PY - 2016 AN - OPUS4-38199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brieger, C. A1 - Melke, J. A1 - van der Bosch, N. A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - de Oliveira Guilherme Buzanich, Ana A1 - Krishna Kayarkatte, M. A1 - Derr, I. A1 - Schökel, A. A1 - Roth, C. ED - de Oliveira Guilherme Buzanich, Ana T1 - A combined in-situ XAS–DRIFTS study unraveling adsorbate induced changes on Pt nanoparticle structure JF - Journal od Catalysis N2 - The adsorption behavior of Platinum nanoparticles was studied for the as-received catalyst (under inert gas), under hydrogen and CO atmosphere using our newly designed in-situ cell. X-ray Absorption Spectroscopy (XAS) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) experiments were performed simultaneously with high data quality. Structural information and the type of adsorbate could be revealed via Extended X-ray Absorption Fine Structure (EXAFS) analysis, Δμ X-ray Absorption Near Edge Structure analysis (Δμ XANES) and in-situ DRIFTS. The as-received catalyst showed sub-surface oxygen and O(n-fold). Under CO atmosphere only CO(atop) was found. Reversible adsorbate induced changes of the Pt nanoparticle structure were derived from changes in the Pt-Pt coordination number and the corresponding bond distance. Under reducing conditions (H2, CO) a significant increase in both values occurred. Temperature dependent desorption of CO revealed a gradual shift from Pt-CO to Pt-O. Reoxidation was clearly assigned to strong metal support interaction from the SiO2 support. KW - X-ray absorption spectroscopy KW - DRIFTS KW - XANES KW - CO adsoprtion KW - Platinum KW - String metal support interaction KW - Silica support KW - Adsorbates KW - Infrared spectroscopy PY - 2016 DO - https://doi.org/10.1016/j.jcat.2016.03.034 SN - 0021-9517 VL - 339 SP - 57 EP - 67 PB - Elsevier AN - OPUS4-38367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wurzler, Nina A1 - Schütter, J. D. A1 - Wagner, R. A1 - Dimper, M. A1 - Lützenkirchen-Hecht, D. A1 - Özcan Sandikcioglu, Özlem T1 - Trained to corrode: Cultivation in the presence of Fe(III) increases the electrochemical activity of iron reducing bacteria – An in situ electrochemical XANES study JF - Electrochemistry Communications N2 - This paper reports results from in situ electrochemical X-ray absorption near-edge spectroscopy (XANES) studies of the corrosion processes on model thin iron films in the presence of iron reducing bacteria Shewanella putrefaciens. Here we investigate the electrochemical activity of two cultures grown in the presence and absence of Fe(III) citrate in the culture medium. The XANES spectra and the OCP data of the Fe sample incubated with the culture grown in absence of Fe(III) did not show any significant changes during twenty hours of monitoring. In the case of the culture grown in Fe(III) containing medium, an accelerated dissolution of the iron film was observed together with the formation of a mixed Fe(II)-Fe(III) hydroxide surface layer. The open circuit potential (OCP) steadily approached the free corrosion potential of iron in neutral chloride containing electrolytes, indicating a continuous dissolution process without passivation. KW - Microbiologically influenced corrosion KW - XANES KW - Electrochemistry KW - Iron reducing bacteria PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505732 DO - https://doi.org/10.1016/j.elecom.2020.106673 VL - 112 SP - 106673 PB - Elsevier B.V. AN - OPUS4-50573 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lutz, C. A1 - Hampel, S. A1 - Ke, X. A1 - Beuermann, S. A1 - Turek, T. A1 - Kunz, U. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Fittschen, U. T1 - Evidence for redox reactions during vanadium crossover inside the nanoscopic water-body of Nafion 117 using X-ray absorption near edge structure spectroscopy JF - Journal of Power Sources N2 - A major source of capacity fade of the common vanadium redox flow battery (VRFB) is the vanadium ion transport through the separator. However, different transport models disagree significantly in the diffusion coefficient for the different V species and the influence of different transport mechanisms. The underlying hypothesis of this work is that reactions inside the membrane are partly responsible for these discrepancies. Accordingly, it was investigated if redox reactions inside the nanoscopic water body of Nafion 117 can occur. X-ray absorption near edge structure spectroscopy (XANES) was used to distinguish between the different V species inside hydrated Nafion 117 and novel PVDF-based membranes. It was validated that the speciation of vanadium can be performed using the pre-edge peak energy and intensity. The experiments were performed as follows: strips of the membrane were exposed from one site to a V3+ solution (green) and from the other site to a VO2+ solution (yellow). The ions could diffuse into the membrane from both sides. A change of color of the membrane strip was observed. The blue color in the middle of the strip indicated that VO2+ was formed where V3+ and VO2+ got in contact. Using XANES this reaction inside Nafion was proven. KW - PVDF-Based membrane KW - VRFB KW - Vanadium speciation KW - XANES KW - Nafion 117 PY - 2020 DO - https://doi.org/10.1016/j.jpowsour.2020.229176 VL - 483 SP - 229176 PB - Elsevier B.V. AN - OPUS4-51719 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana A1 - Kulow, Anicó A1 - Kabelitz, Anke A1 - Grunewald, C. A1 - Seidel, R. A1 - Chapartegui-Arias, Ander A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Beyer, S. T1 - Observation of early ZIF-8 crystallization stages with X-ray absorption spectroscopy JF - Soft Matter N2 - The present study investigates early stages of ZIF-8 crystallization up to 5 minutes post mixing of precursor solutions. Dispersive X-ray Absorption Spectroscopy (DXAS) provides a refined understanding of the evolution of the coordination environment during ZIF-8 crystallization. Linear Combination Fiting (LCF) suggests tetrakis(1-methylimidazole)zinc2+ to be a suitable and stable mononuclear structure analogue for some early stage ZIF-8 intermediates. Our results pave the way for more detailed studies on physico-chemical aspects of ZIF-8 crystallization to better control tailoring ZIF-8 materials for specific applications. KW - In-situ KW - XANES KW - ZIF-8 KW - Crystallization PY - 2020 DO - https://doi.org/10.1039/D0SM01356K SN - 1744-6848 VL - 17 IS - 2 SP - 331 EP - 334 PB - Royal Scociety of Chemistry AN - OPUS4-51723 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Olivera, Paulo A1 - Michalchuk, Adam A1 - de Oliveira Guilherme Buzanich, Ana A1 - Bienert, Ralf A1 - Torresi, R. A1 - Camargo, P. A1 - Emmerling, Franziska T1 - Tandem X-ray absorption spectroscopy and scattering for in situ time-resolved monitoring of gold nanoparticle mechanosynthesis JF - ChemComm N2 - Current time-resolved in situ approaches limit the scope of mechanochemical investigations possible. Here we develop a new, general approach to simultaneously follow the evolution of bulk atomic and electronic structure during a mechanochemical synthesis. This is achieved by coupling two complementary synchrotron-based X-ray methods: X-ray absorption spectroscopy (XAS) and X-ray diffraction. We apply this method to investigate the bottom-up mechanosynthesis of technologically important Au micro and nanoparticles in the presence of three different reducing agents, hydroquinone, sodium citrate, and NaBH4. Moreover, we show how XAS offers new insight into the early stage generation of growth species (e.g. monomers and clusters), which lead to the subsequent formation of nanoparticles. These processes are beyond the detection capabilities of diffraction methods. This combined X-ray approach paves the way to new directions in mechanochemical research of advanced electronic materials. KW - Mechanochemistry KW - XANES KW - X-ray diffraction KW - Nano particles PY - 2020 DO - https://doi.org/10.1039/d0cc03862h SN - 1364-548X VL - 56 SP - 10329 EP - 10332 PB - Royal Society of Chemistry AN - OPUS4-51760 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wurzler, Nina A1 - Schutter, Jan David A1 - Wagner, R. A1 - Dimper, Matthias A1 - Lützenkirchen-Hecht, D. A1 - Özcan Sandikcioglu, Özlem T1 - Abundance of Fe(III) during cultivation affects the microbiologically influenced corrosion (MIC) behaviour of iron reducing bacteria Shewanella putrefaciens JF - Corrosion Science N2 - The effect of the presence of Fe(III) during the cultivation on the electrochemical activity and corrosion behaviour of dissimilatory iron reducing bacteria Shewanella putrefaciens was studied by means of ex situ and in situ X-ray absorption near-edge spectroscopy (XANES). Stainless steel AISI 304 and thin iron films were studied as substrates. XANES analysis indicated an accelerated iron dissolution and growth of an oxide/hydroxide film for the culture grown with Fe(III) in comparison to the culture grown in absence of Fe(III). Electrochemical Analysis indicated that the biofilm resulted in acceleration of the general corrosion but provides protection against local corrosion. KW - Stainless Steel KW - XANES KW - Iron KW - Cyclic Voltammetry KW - Microbiological Corrosion PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513788 DO - https://doi.org/10.1016/j.corsci.2020.108855 VL - 174 SP - 108855 PB - Elsevier Ltd. AN - OPUS4-51378 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wurzler, Nina A1 - Wagner, Ralph A1 - Schutter, Jan David A1 - Das, Chayanika A1 - Dimper, Matthias A1 - An, Biwen A1 - Koerdt, Andrea A1 - Lützenkirchen-Hecht, Dirk A1 - Özcan Sandikcioglu, Özlem T1 - Effect of cultivation conditions on the electrochemical activity of metal reducing bacteria (mrb) on stainless steel surfaces N2 - Investigation of the electrochemical activity of two cultures grown with and without abundance of Fe(III) and their different ability to reduce and therefore dissolve iron oxides in steel and model iron thin films. T2 - Eurocorr2019 CY - Sevilla, Spain DA - 09.09.2019 KW - X-ray spectroscopic techniques KW - Microbiologically influenced corrosion KW - MIC KW - XANES KW - Metal reducing bacteria KW - In situ PY - 2019 AN - OPUS4-49692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Özcan Sandikcioglu, Özlem A1 - Wurzler, Nina A1 - Witt, Julia A1 - Dimper, Matthias A1 - Wagner, R. A1 - Lützenkirchen-Hecht, D. T1 - Changes in passive film chemistry of stainless steels in the presence of iron reducing bacteria N2 - Summary of the results obtained at DELTA-Beamline 8 in 2018. T2 - DELTA User Treffen CY - Dortmund, Germany DA - 28.11.2018 KW - MIC KW - Corrosion KW - XANES PY - 2018 AN - OPUS4-50312 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wurzler, Nina A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Kunte, Hans-Jörg A1 - Özcan Sandikcioglu, Özlem T1 - Changes in the passive film chemistry on stainless steels during microbiologically influenced corrosion: A combined electrochemistry and XANES study N2 - Metal reducing bacteria (MRB) are capable of utilizing different metals, such as iron, chromium, manganese or uranium as well as many organic compounds, as electron acceptors for their metabolism. Via direct and indirect electron transfer processes MRB are able to convert insoluble passive film species like Fe(III)-oxides to soluble Fe(II)-oxides and hydroxides. This weakening of the passive film not only leads to an acceleration of the general corrosion processes, but also increases the susceptibility of stainless steels to pitting corrosion. Electron transfer mechanisms are not yet fully understood and the role of bacteria in corrosion processes is controversially discussed in the literature. Moreover, recent research indicates that the secretion of electron shuttles like riboflavins by MRB also contributes to the extracellular electron transfer. This project aims at clarifying the chemical and electrochemical interaction mechanisms of MRB with stainless steel surfaces. To investigate the changes in the oxide chemistry on the stainless steel surface in the presence of biomolecules and MRB a new flow cell has been designed and constructed which enables the collection of XANES (X-ray Absorption Near Edge Structure) spectra in fluorescence mode at the Fe K-edge and electrochemical analysis. Availability of oxygen and the pre-exposure of the MRB to Fe(III) during cultivation have been investigated as parameters with significant effect on the corrosion rates. XANES analysis is supplemented by ex-situ X-Ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) to complete the surface characterisation in terms of the oxide chemistry and the composition of organic residues. Complementary electrochemical quartz crystal microbalance (e-QCM) measurements have been performed to quantify the kinetics of bacterial attachment and biofilm formation. Together with the frequency shift, the evolution of the dissipation signal has been analyzed to investigate the changes in viscosity and structure of the biofilm from initial stages up to maturation. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) has been used to study the structure and viscoelastic properties of the biofilms after e-QCM experiments. The presentation will summarize our results on the effects of individual surface and environment related parameters on the chemical/electrochemical interaction mechanisms of MRB leading to passive film degradation on stainless steel surfaces and provide useful insights from a fundamental aspect for the development of novel mitigation strategies for microbiologically influenced corrosion. T2 - EUROCORR 2017 & 20thICC CY - Prague, Czech Republic DA - 04.09.2017 KW - Microbiologically influenced corrosion (MIC) KW - XANES KW - Stainless steel KW - Corrosion PY - 2017 AN - OPUS4-43407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Özcan Sandikcioglu, Özlem A1 - Kastanias, Elaine A1 - Wurzler, Nina A1 - Hampel, Marco T1 - Spektroelektrochemische Analyse der Korrosionsprozesse von eisenreduzierenden Mikroorganismen N2 - Der Vortrag ist eine Zusammenfassung der Forschungsaktivitäten im FB 6.2 im Rahmen des Themenfeldprojekts MIC (TF-Material). T2 - DECHEMA/GfKORR-Fachgruppe "Mikrobielle Materialzerstörung und Materialschutz" CY - Berlin, Germany DA - 04.10.2017 KW - Korrosion KW - Mikrobiell induzierte Korrosion (MIC) KW - Lokale Elektrochemie KW - Spektroelektrochemie KW - Oberflächenverstärkte Raman Spektroskopie (SERS) KW - XANES PY - 2017 AN - OPUS4-43462 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nützmann, Kathrin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Stephan-Scherb, Christiane A1 - Emmerling, Franziska T1 - Depth dependent phase identification of corrosion zones in ferritic alloys by micro-X-ray absorption near edge structure spectroscopy N2 - Ferritic steels with chromium contents up to 13 wt% are used as materials for power plant components as boiler materials (< 2 wt% Cr) and super heater tubes (> 9 wt% Cr). These materials are subject to aggressive corrosion caused by hot gases such as CO2, H2O, O2 and SO2. Especially SO2 causes fatal corrosion even as a minor component. To examine sulfurous corrosion mechanisms, experiments with pure SO2 were conducted. A proper analysis of the material changes requires phase identification and quantification with a high lateral resolution within the corrosion scale. T2 - ANAKON2017 CY - Tübingen, Germany DA - 03.04.2017 KW - Corosion KW - Steel KW - XANES PY - 2017 AN - OPUS4-40415 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stephan-Scherb, Christiane A1 - Menneken, Martina A1 - Nützmann, Kathrin A1 - Falk, Florian A1 - de Oliveira Guilherme Buzanich, Ana A1 - Witte, Steffen A1 - Radtke, Martin T1 - Early stages of high temperature oxidation/sulfidation studied by synchrotron x-ray diffraction and spectroscopy N2 - Ferritic high temperature alloys are widely used as boiler tube and heat exchanger materials in coal, biomass and co-fired power plants. All technologies have in common that the applied materials are exposed to different temperatures, process pressures and reactive atmospheres that lead to a change of the material properties and a further degradation of the material. Material changes caused by aging in highly corrosive and toxic gases such as SO2 are mainly studied ex situ after the reaction is finished. The solid material is deposited in the atmosphere for a certain period of time, and material changes are then examined by various microscopic techniques such as optical microscopy (OM), electron microprobe analysis (EMPA), scanning electron microscopy (SEM and TEM) and X-ray diffraction (XRD). Nevertheless, extensive efforts were made to study material changes of high temperature alloys under oxidizing and reducing atmospheres by environmental scanning electron microscopy or in situ TEM techniques However, the possibilities of microscopic in situ techniques are very limited for the use of highly corrosive and toxic gases such as SO2. Since Sulfur induced corrosion at temperatures relevant for coal and biomass fired power plants, which is causing breakaway oxidation and sulfide precipitation at grain boundaries, is still of scientific interest, the current work focuses on the effect of SO2 in an initial stage of corrosion of ferritic alloys. For the analysis of early stages of combined oxidation and sulphidation processes of Fe-Cr model alloys the usage of a light furnace to conduct a rapid reactive annealing experiment is feasible. Previous studies presented distinct results of the influence of chromium on early high temperature corrosion by SO2 by this technique and subsequent classical metallographic analyses. However, it is still not possible to trace the corrosion mechanism in real time by conducting single aging experiments. The current work introduces two different approaches to study the initial stages of high temperature oxidation processes by applying above state of the art X-ray diffraction and spectroscopy methods. One part focuses on the real time observation of the formation of corrosion products such as oxides and sulfides by energy dispersive X-ray diffraction (EDXRD). The potential of this technique to study crystallization and growth processes of thin films in a reactive environment in real time was previously shown for different compound semiconductors. This approach was now applied to follow oxidation and sulphidation processes of ferritic model alloys in SO2 and SO2/H2O environments. The diffraction signals of the X-rays were detected during the corrosion process and the peak area and positions were analyzed as a function of time. This procedure enables monitoring external oxide growth and material loss in real time in an early stage of corrosion. The other part of the current work presents the possibilities of X-ray absorption near edge structure spectroscopy (XANES) to characterize oxide scales and their growth mechanisms. Precise phase identification and quantification of corrosion products in a multi-phase oxide/sulfide scale is a pre-requisite to understand diffusion paths of metal ions and gas components. It is a challenging task to distinguish structurally similar reaction products such as Fe3O4 and FeCr2O4 especially in thin films with texture effects by diffraction. To illustrate for example Cr-out diffusion of an alloy throughout an inner and external oxide scale the differentiation of Fe3O4 and FeCr2O4 is indispensable. XANES uses the photoionization effect at the metal absorption edge in an aging product and accesses by this structural and chemical information. The current work uses XANES at the Fe-K and Cr-K absorption edge to identify various aging products grown as thin layers on alloys after short time aging experiments. A reaction chamber for combining high temperature oxidation experiments with surface sensitive X-ray absorption near edge structure spectroscopy will be introduced and first results of XANES on scales at high temperatures will be presented. T2 - ISHOC 2018 CY - Matsue, Japan DA - 22.10.2018 KW - Corrosion KW - Sulfidation KW - In situ KW - Diffraction KW - XANES PY - 2018 AN - OPUS4-47278 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stephan-Scherb, Christiane A1 - Nützmann, Kathrin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Menneken, Martina A1 - Falk, Florian T1 - High temperature oxidation/sulfidation meets X-ray absorption near edge structure spectroscopy (XANES) N2 - Ferritic-martensitic alloys with 12-16 % Cr in weight are subject to devices for various energy systems, such as coal power plants and waste incineration plants. These materials are exposed to a highly corrosive environment which lead to a degradation of the material. Especially the simultaneous oxidation and sulfidation is thereby of special interest. Proper spatially resolved measurements that determine not only chemical compositions but phases are rare. However, precise phase identification and quantification of corrosion products within the multi-phase corrosion scales is a key aspect to understand diffusion paths of metal ions and gas ions/molecules. This study investigated Fe-Cr model alloys with Cr contents from 0 to 13 % in weight in 0.5 % SO2 and 99.5 % Ar atmosphere to aim in a fundamental and systematic analysis. Samples were aged at 650 °C for time scales from 12 h to 250 h. The results presented here correspond to depth dependent phase identification of oxide and sulphide phases in the corrosion scales by using X-ray absorption near edge spectroscopy (XANES). Per sample a series of ca. 20 spots (1-5 µm spot size) from scale-gas to scale-metal interface were measured. XANES spectroscopy was performed at the Fe-K edge (7.11 keV) on polished cross sections. The collected spectra were fitted to a combination of reference materials to quantify the present phases at different positions within the scale.The phase distribution differs with Cr content and the Cr diffusion through pure Fe-oxide and mixed Fe-Cr-oxide phases is discussed. T2 - EFC Workshop "High Temperature Corrosion" CY - Frankfurt am Main, Germany DA - 26.09.2018 KW - High temperature corrosion KW - XANES PY - 2018 AN - OPUS4-47277 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szczerba, Wojciech A1 - Costo, R. A1 - Veintemillas-Verdaguer, S. A1 - del Puerto Morales, M. A1 - Thünemann, Andreas T1 - SAXS analysis of single- and multi-core iron oxide magnetic nanoparticles JF - Journal of Applied Crystallography N2 - This article reports on the characterization of four superparamagnetic iron oxide nanoparticles stabilized with dimercaptosuccinic acid, which are suitable candidates for reference materials for magnetic properties. Particles p1 and p2 are single-core particles, while p3 and p4 are multi-core particles. Small-angle X-ray scattering analysis reveals a lognormal type of size distribution for the iron oxide cores of the particles. Their mean radii are 6.9 nm (p1), 10.6 nm (p2), 5.5 nm (p3) and 4.1 nm (p4), with narrow relative distribution widths of 0.08, 0.13, 0.08 and 0.12. The cores are arranged as a clustered network in the form of dense mass fractals with a fractal dimension of 2.9 in the multi-core particles p3 and p4, but the cores are well separated from each other by a protecting organic shell. The radii of gyration of the mass fractals are 48 and 44 nm, and each network contains 117 and 186 primary particles, respectively. The radius distributions of the primary particle were confirmed with transmission electron microscopy. All particles contain purely maghemite, as shown by X-ray absorption fine structure spectroscopy KW - Superparamagnetic nanoparticles KW - Iron oxide KW - Reference materials KW - SAXS KW - Small-angle x-ray scattering KW - XANES KW - X-ray absorption near-edge structure KW - X-ray absorption fine structure PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-395948 DO - https://doi.org/10.1107/S1600576717002370 SN - 1600-5767 VL - 50 IS - Part 2 SP - 481 EP - 488 PB - (IUCr) International Union of Crystallography AN - OPUS4-39594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kunkel, Benny A1 - Seeburg, Dominik A1 - Kabelitz, Anke A1 - Witte, Steffen A1 - Gutmann, Torsten A1 - Breitzke, Hergen A1 - Buntkowsky, Gerd A1 - Guilherme Buzanich, Ana A1 - Wohlrab, Sebastian T1 - Highly productive V/Zn-SiO2 catalysts for the selective oxidation of methane JF - Catalysis Today N2 - The production of formaldehyde on industrial scale requires huge amounts of energy due to the involvement of reforming processes in combination with the demand in the megaton scale. Hence, a direct route for the transformation of (bio)methane to formaldehyde would decrease costs and puts less pressure on the environment. Herein, we report on the use of zinc modified silicas as possible support materials for vanadium catalysts and the resulting consequences for the performance in the selective oxidation of methane to formaldehyde. After optimization of the Zn content and reaction conditions, a remarkably high space-time yield of 12.4 kgCH2O⋅kgcat − 1 ⋅h− 1 was achieved. As a result of the extensive characterization by means of UV–vis, Raman, XANES and NMR spectroscopy it was found that vanadium is in the vicinity of highly dispersed zinc atoms which promote the formation of active vanadium species as supposed by theoretical calculations. This work presents a further step of catalyst development towards direct industrial methane conversion which may help to overcome current limitations in the future. KW - Catalysis KW - XANES KW - Selective oxidation PY - 2024 DO - https://doi.org/10.1016/j.cattod.2024.114643 SN - 0920-5861 VL - 432 SP - 1 EP - 13 PB - Elsevier B.V. AN - OPUS4-60137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -