TY - JOUR A1 - Karafiludis, Stephanos A1 - de Oliveira Guilherme Buzanich, Ana A1 - Kochovski, Z. A1 - Feldmann, Ines A1 - Emmerling, Franziska A1 - Stawski, Tomasz T1 - Ni- and Co-Struvites: Revealing Crystallization Mechanisms and Crystal Engineering toward Applicational Use of Transition Metal Phosphates N2 - Industrial and agricultural waste streams (waste water, sludges, tailings, etc.) which contain high concentrations of NH4+, PO43–, and transition metals are environmentally harmful and toxic pollutants. At the same time, phosphorous and transition metals constitute highly valuable resources. Typically, separate pathways have been considered to extract hazardous transition metals or phosphate independently from each other. Investigations on the simultaneous removal of multiple components have been carried out only to a limited extent. Here, we report the synthesis routes for Ni- and Co-struvites (NH4MPO4·6H2O, M = Ni2+ and Co2+), which allow for P, ammonia, and metal co-precipitation. By evaluating different reaction parameters, the phase and stability of transition metal struvites as well as their crystal morphologies and sizes could be optimized. Ni-struvite is stable in a wide reactant concentration range and at different metal/phosphorus (M/P) ratios, whereas Co-struvite only forms at low M/P ratios. Detailed investigations of the precipitation process using ex situ and in situ techniques provided insights into the crystallization mechanisms/crystal engineering of these materials. M-struvites crystallize via intermediate colloidal amorphous nanophases, which subsequently aggregate and condense to final crystals after extended reaction times. However, the exact reaction kinetics of the formation of a final crystalline product varies significantly depending on the involved metal cation in the precipitation process: several seconds (Mg) to minutes (Ni) to hours (Co). The achieved level of control over the morphology and size makes precipitation of transition metal struvites a promising method for direct metal recovery and binding them in the form of valuable phosphate raw materials. Under this paradigm, the crystals can be potentially up-cycled as precursor powders for electrochemical or (electro)catalytic applications, which require transition metal phosphates. KW - Crystallization KW - Struvite KW - Nickel KW - Cobalt KW - Phosphorous recovery KW - Up-cycling KW - Aqueous synthesis PY - 2022 U6 - https://doi.org/10.1021/acs.cgd.2c00284 VL - 22 IS - 7 SP - 4305 EP - 4315 PB - ACS Publications CY - Washington D.C. AN - OPUS4-55286 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Iro, M. A1 - Ingerle, D. A1 - Radtke, Martin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Kregsamer, P. A1 - Streli, C. T1 - Investigation of polycapillary half lenses for quantitative confocal micro-X-ray fluorescence analysis N2 - The use of polycapillary optics in confocal micro-X-ray fluorescence analysis (CMXRF) enables the destruction-free 3D investigation of the elemental composition of samples. The energy-dependent transmission properties, concerning intensity and spatial beam propagation of three polycapillary half lenses, which are vital for the quantitative interpretation of such CMXRF measurements, are investigated in a monochromatic confocal laboratory setup at the Atominstitut of TU Wien, and a synchrotron setup on the BAMline beamline at the BESSY II Synchrotron, Helmholtz-Zentrum-Berlin. The empirically established results, concerning the intensity of the transmitted beam, are compared with theoretical values calculated with the polycap software package and a newly presented analytical model for the transmission function. The resulting form of the newly modelled energy-dependent transmission function is shown to be in good agreement with Monte Carlo simulated results for the complete energy regime, as well as the empirically established results for the energy regime between 6 keV and 20 keV. An analysis of possible fabrication errors was conducted via pinhole scans showing only minor fabrication errors in two of the investigated polycapillary optics. The energy-dependent focal spot size of the primary polycapillary was investigated in the laboratory via the channel-wise evaluation of knife-edge scans. Experimental results are compared with data given by the manufacturer as well as geometric estimations for the minimal focal spot size. Again, the resulting measurement points show a trend in agreement with geometrically estimated results and manufacturer data. KW - BAMline KW - Synchrotron KW - Capillary KW - confocal PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-562430 SN - 1600-5775 VL - 29 SP - 1376 EP - 1384 PB - International Union of Crystallography CY - Chester AN - OPUS4-56243 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de O. Primo, J. A1 - Horsth, D.F. A1 - de S. Correa, J. A1 - Das, A. A1 - Bittencourt, C. A1 - Umek, P. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Yusenko, Kirill A1 - Zanetta, C. A1 - Anaissi, F.J. T1 - Synthesis and Characterization of Ag/ZnO Nanoparticles for Bacteria Disinfection in Water N2 - n this study, two green synthesis routes were used for the synthesis of Ag/ZnO nanoparticles, using cassava starch as a simple and low-cost effective fuel and Aloe vera as a reducing and stabilizing agent. The Ag/ZnO nanoparticles were characterized and used for bacterial dis- infection of lake water contaminated with Escherichia coli (E. coli). Characterization indicated the formation of a face-centered cubic structure of metallic silver nanoparticles with no insertion of Ag into the ZnO hexagonal wurtzite structure. Physicochemical and bacteriological analyses described in “Standard Methods for the Examination of Water and Wastewater” were used to evaluate the efficiency of the treatment. In comparison to pure ZnO, the synthesized Ag/ZnO nanoparticles showed high efficiencies against Escherichia coli (E. coli) and general coliforms present in the lake water. These pathogens were absent after treatment using Ag/ZnO nanoparticles. The results indicate that Ag/ZnO nanoparticles synthesized via green chemistry are a promising candidate for the treatment of wastewaters contaminated by bacteria, due to their facile preparation, low-cost synthesis,and disinfection efficiency. KW - Synchrotron KW - BAMline PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-562440 SN - 2079-4991 VL - 12 IS - 10 SP - 1 EP - 18 PB - MDPI CY - Basel AN - OPUS4-56244 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana A1 - Michalchuk, Adam A1 - Cakir, Cafer Tufan A1 - Haider, M. B. A1 - Yusenko, Kirill A1 - Radtke, Martin A1 - Reinholz, U. A1 - Emmerling, Franziska T1 - Time resolved in situ monitoring of mechanochemical transformations by X-ray spectroscopy (XAS) N2 - Mechanochemical reactions promise a new direction for environmentally benign preparation of materials, and has been dubbed by IUPAC as one of the 10 chemical innovations that will change our world. Despite this significant promise, very little is known about the mechanisms that drive mechanochemical transformations, posing significant barriers to realizing their full potential. To this end, there is growing need to follow mechanochemical reactions in situ and in real time. We here describe advances in the development and application of XAS methods to monitor material synthesis in real time under mechanochemical conditions. We demonstrate the generality of our approaches by describing mechanochemical syntheses of materials by both vibratory ball milling and by Resonant Acoustic Mixing (RAM), where a time resolution of 1 second is for a whole XAS spectrum was achieved. Moreover, we describe how spectroscopic methods can be coupled to diffraction-based approaches, thereby providing new dimensions in understanding mechanochemical synthesis. T2 - AfLS3 CY - Online meeting DA - 14.11.2021 KW - Dipsersive XAS KW - Mechanochemistry KW - Time-resolved KW - In situ PY - 2021 AN - OPUS4-56256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana A1 - Michalchuk, Adam A1 - Cakir, Cafer Tufan A1 - Yusenko, Kirill A1 - Radtke, Martin A1 - Reinholz, U. A1 - Emmerling, Franziska T1 - Time resolved in situ monitoring of mechanochemical transformations by X-ray spectroscopy (XAS) N2 - Mechanochemical reactions promise a new direction for environmentally benign preparation of materials, and has been dubbed by IUPAC as one of the 10 chemical innovations that will change our world. Despite this significant promise, very little is known about the mechanisms that drive mechanochemical transformations, posing significant barriers to realizing their full potential. To this end, there is growing need to follow mechanochemical reactions in situ and in real time. We here describe advances in the development and application of XAS methods to monitor material synthesis in real time under mechanochemical conditions. We demonstrate the generality of our approaches by describing mechanochemical syntheses of materials by both vibratory ball milling and by Resonant Acoustic Mixing (RAM), where a time resolution of 1 second is for a whole XAS spectrum was achieved. Moreover, we describe how spectroscopic methods can be coupled to diffraction-based approaches, thereby providing new dimensions in understanding mechanochemical synthesis. T2 - Denver X-ray Conference: DXC 2021 CY - Online meeting DA - 02.08.2021 KW - Dispersive XAS KW - Mechanochemistry KW - Time resolved KW - In situ PY - 2021 AN - OPUS4-56257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana T1 - Time resolved in situ monitoring of mechanochemical transformations by X-ray absorption spectroscopy (XAS) N2 - Mechanochemical reactions promise a new direction for environmentally benign preparation of materials, and has been dubbed by IUPAC as one of the 10 chemical innovations that will change our world. Despite this significant promise, very little is known about the mechanisms that drive mechanochemical transformations, posing significant barriers to realizing their full potential. To this end, there is growing need to follow mechanochemical reactions in situ and in real time. We here describe advances in the development and application of XAS methods to monitor material synthesis in real time under mechanochemical conditions. We demonstrate the generality of our approaches by describing mechanochemical syntheses of materials by both vibratory ball milling and by Resonant Acoustic Mixing (RAM), where a time resolution of 1 second is for a whole XAS spectrum was achieved. Moreover, we describe how spectroscopic methods can be coupled to diffraction-based approaches, thereby providing new dimensions in understanding mechanochemical synthesis. T2 - European Conference on X-ray Spectrometry 2022 CY - Bruges, Belgium DA - 27.06.2022 KW - XAS KW - Mechanochemictry KW - Time resolved KW - In situ PY - 2022 AN - OPUS4-56258 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana T1 - Time resolved in situ monitoring of mechanochemical transformations by X-ray absorption spectroscopy (XAS) N2 - Mechanochemical reactions promise a new direction for environmentally benign preparation of materials, and has been dubbed by IUPAC as one of the 10 chemical innovations that will change our world. Despite this significant promise, very little is known about the mechanisms that drive mechanochemical transformations, posing significant barriers to realizing their full potential. To this end, there is growing need to follow mechanochemical reactions in situ and in real time. We here describe advances in the development and application of XAS methods to monitor material synthesis in real time under mechanochemical conditions. We demonstrate the generality of our approaches by describing mechanochemical syntheses of materials by both vibratory ball milling and by Resonant Acoustic Mixing (RAM), where a time resolution of 1 second is for a whole XAS spectrum was achieved. Moreover, we describe how spectroscopic methods can be coupled to diffraction-based approaches, thereby providing new dimensions in understanding mechanochemical synthesis. T2 - Advances X ray Analytics Seminar at TU Berlin CY - Berlin, Germany DA - 14.06.2022 KW - XAS KW - Mechanochemistry KW - Time resolved KW - In situ PY - 2022 AN - OPUS4-56259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Flatken, M. A. A1 - Radicchi, E. A1 - Wendt, R. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Härk, E. A1 - Pascual, J. A1 - Mathies, F. A1 - Shargaieva, O. A1 - Prause, A. A1 - Dallmann, A. A1 - De Angelis, F. A1 - Hoell, A. A1 - Abate, A. T1 - Role of the Alkali Metal Cation in the Early Stages of Crystallization of Halide Perovskites N2 - ABX3 metal halide perovskites revolutionized the research and development of new optoelectronics, including solar cells and light-emitting diodes. Processing polycrystalline thin films from precursor solutions is one of the core advantages of these materials since it enables versatile and cost-effective manufacturing. The perovskite film morphology, that is, continuous substrate coverage and low surface roughness, is of paramount importance for highly efficient solar cells and optoelectronic devices in general. Controlling the chemistry of precursor solutions is one of the most effective strategies to manage the perovskite film morphology. Herein, we show the fundamental influence of the A-site cation composition on the perovskite precursor arrangement and the consequent film formation. Extended X-ray absorption fine structure spectroscopy and small-angle X-ray scattering give unprecedented insights into the complex structural chemistry of the perovskite precursors and, in particular, their repulsive interactions as a crucial parameter for colloidal stability. Combining these techniques with in situ grazing incidence wide-angle X-ray scattering during thin-film formation allows us to identify the mechanism for using alkali metals as a decisive criterion to control the colloidal stability of the perovskite precursor and thus the thin-film morphology. We illustrate the fundamental principle behind the systematic use of alkali metals regardless of whether they are incorporated in the lattice or not. Hence, this work provides tools to selectively control the morphology and crystal growth in present and future systems KW - MAPbI3 perovskites KW - Halide Perovskites KW - X-ray absorption spectroscopy PY - 2022 U6 - https://doi.org/10.1021/acs.chemmater.1c03563 SN - 0897-4756 VL - 34 IS - 3 SP - 1121 EP - 1131 PB - American Chemical Society AN - OPUS4-54713 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulow, Anicó A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Hampel, S. A1 - Fittschen, UEA A1 - Streli, C. A1 - Radtke, Martin T1 - Reconstruction for coded aperture full-field x-ray fluorescence imaging N2 - X-ray fluorescence imaging is a well-established tool in materials characterization. In this work, we present the adaption of coded aperture imaging to full-field X-ray fluorescence imaging at the synchrotron. Coded aperture imaging has its origins in astrophysics, and has several advantages: Coded apertures are relatively easy to fabricate, achromatic, allow a high photon throughput, and high angular acceptance. Coded aperture imaging is a two-step-process, consisting of the measurement process and a reconstruction step. Different programs have been written, for the raytracing/forward projection and the reconstruction. Experiments with coded aperture in combination with a Color X-ray Camera and an energy-dispersive area detector, have been conducted at the BAMline. Measured samples were successfully reconstructed, and gave a 9.1-fold increase in count rate compared to a polycapillary optic. KW - Synchrotron KW - BAMline KW - Coded Aperture PY - 2022 SN - 1097-0002 VL - 65 SP - 57 EP - 70 PB - Cambridge University Press CY - Cambridge AN - OPUS4-56350 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - C. Pardo Pérez, L. A1 - Arndt, A. A1 - Stojkovikj, S. A1 - Y. Ahmet, I. A1 - T. Arens,, J. A1 - Dattila, F. A1 - Wendt, R. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Davies, V. A1 - Höflich, K. A1 - Köhnen, E. A1 - Tockhorn, P. A1 - Golnak, R. A1 - Xiao, J. A1 - Schuck, G. A1 - Wollgarten, M. A1 - López, N. A1 - T. Mayer, M. T1 - Determining Structure-Activity Relationships in Oxide Derived CuSn Catalysts During CO2 Electroreduction Using X-Ray Spectroscopy N2 - The development of earth-abundant catalysts for selective electrochemical CO2 conversion is a central challenge. Cu-Sn bimetallic catalysts can yield selective CO2 reduction toward either CO or formate. This study presents oxide-derived Cu-Sn catalysts tunable for either product and seeks to understand the synergetic effects between Cu and Sn causing these selectivity trends. The materials undergo significant transformations under CO2 reduction conditions, and their dynamic bulk and surface structures are revealed by correlating observations from multiple methods—X-ray absorption spectroscopy for in situ study, and quasi in situ X-ray photoelectron spectroscopy for surface sensitivity. For both types of catalysts, Cu transforms to metallic Cu0 under reaction conditions. However, the Sn speciation and content differ significantly between the catalyst types: the CO-selective catalysts exhibit a surface Sn content of 13 at. % predominantly present as oxidized Sn, while the formate-selective catalysts display an Sn content of ≈70 at. % consisting of both metallic Sn0 and Sn oxide species. Density functional theory simulations suggest that Snδ+ sites weaken CO adsorption, thereby enhancing CO selectivity, while Sn0 sites hinder H adsorption and promote formate production. This study reveals the complex dependence of catalyst structure, composition, and speciation with electrochemical bias in bimetallic Cu catalysts. KW - Electrochemical CO2 conversion KW - Cu catalysts KW - X-ray absorption spectroscopy PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-547116 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 - Martins, Ines A1 - Al-Sabbagh, Dominik A1 - Bentrup, U. A1 - Marquardt, Julien A1 - Schmid, Thomas A1 - Scoppola, E. A1 - Kraus, Werner A1 - Stawski, Tomasz A1 - de Oliveira Guilherme Buzanich, Ana A1 - Yusenko, Kirill A1 - Weidner, Steffen A1 - Emmerling, Franziska T1 - Formation Mechanism of a Nano-Ring of Bismuth Cations and Mono-Lacunary Keggin-Type Phosphomolybdate N2 - A new hetero-bimetallic polyoxometalate (POM) nano-ring was synthesized in a one-pot procedure. The structure consists of tetrameric units containing four bismuth-substituted monolacunary Keggin anions including distorted [BiO8] cubes. The nano-ring is formed via self-assembly from metal precursors in aqueous acidic medium. The compound (NH4)16[(BiPMo11O39)4] ⋅ 22 H2O; (P4Bi4Mo44) was characterized by single-crystal X-ray diffraction, extended X-ray absorption fine structure spectroscopy (EXAFS), Raman spectroscopy, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF), and thermogravimetry/differential scanning calorimetry mass spectrometry (TG-DSC-MS). The formation of the nano-ring in solution was studied by time-resolved in situ small- and wide-angle X-ray scattering (SAXS/WAXS) and in situ EXAFS measurements at the Mo−K and the Bi−L3 edge indicating a two-step process consisting of condensation of Mo-anions and formation of Bi−Mo-units followed by a rapid self-assembly to yield the final tetrameric ring structure. KW - Bismuth KW - In situ EXAFS KW - In situ SAXS/WAXS KW - Lacunary Keggin ion KW - Polyoxometalates KW - Self-assembly PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-546823 SN - 0947-6539 VL - 28 IS - 27 SP - 1 EP - 7 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yusenko, Kirill A1 - Kabelitz, Anke A1 - Schokel, Alexander A1 - Wagner, Ralf A1 - Prinz, Carsten A1 - Kemnitz, E A1 - Emmerling, Franziska A1 - Krahl, Thoralf A1 - de Oliveira Guilherme Buzanich, Ana T1 - Local Structure of Europium-Doped Luminescent Strontium Fluoride Nanoparticles: Comparative X-ray Absorption Spectroscopy and Diffraction Study N2 - Rare-earth based luminescent materials are key functional components for the rational design of light-conversion smart devices. Stable Eu3+-doped strontium fluoride (SrF2) nanoparticles were prepared at room temperature in ethylene glycol. Their luminescence depends on the Eu content and changes after heat treatment. The crystallinity of heat-treated material increases in comparison with as-synthesized samples. Particles were investigated in solution using X-ray diffraction, small-angle X-ray scattering, and X-ray spectroscopy. After heat treatment, the size of the disordered nanoparticles increases together with a change of their local structure. Interstitial fluoride ions can be localized near Eu3+ ions. Therefore, non-radiative relaxation from other mechanisms is decreased. Knowledge about the cation distribution is key information for understanding the luminescence properties of any material. KW - SrF2 KW - EXAFS KW - Eu PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-540094 VL - 7 IS - 11 SP - 1221 EP - 1229 PB - Wiley Online Library AN - OPUS4-54009 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-543606 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 - CONF A1 - Yusenko, Kirill A1 - Emmerling, Franziska A1 - de Oliveira Guilherme Buzanich, Ana T1 - X-Ray absorption spectroscopy to study multicomponent materials N2 - Detailed study of multicomponent systems in solid-state as well as in solution using X-ray diffraction and X-ray spectroscopy is one of the most common topics in modern materials chemistry. 5-6 component high-entropy alloys such as fcc- and bcc-structured AlxCoCrFeNi and fluorescent nanoparticles based on fluorite-structured SrF2 doped by rare-earth metals in organic solutions have high complexity and their local structure cannot be resolved using only diffraction. X-ray absorption spectroscopy should be applied to understand peculiarities in their local structure and make a link between structure on short and long ranges and their macroscopic properties. Here, based on two representativee examples, we discuss how a combination of several X-ray absorption edges might give new insights into complex materials. T2 - Virtual meeting of the African Light Source CY - Online meeting DA - 15.11.2021 KW - EXAFS KW - Synchrotron studies PY - 2021 AN - OPUS4-54014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yusenko, Kirill A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin T1 - Studies of high-entropy alloys using x-ray absorption fine structure at the bamline N2 - BAM line is multipurpose high-energy beamline. To extend studies of multicomponent alloys using EXAFS we perform own research and user experiments requiring multiedge spectroscopy, high-temperature and chemically aggressive sample environments. Our study of multicomponent alloys and high-entropy alloys open new perspectives in understanding their reactivity, corrosion, phase transformations and local ordering. T2 - SPP2006: large scale facilities CY - Online meeting DA - 02.11.2021 KW - Synchrotron studies KW - High-entropy alloys KW - EXAFS PY - 2021 AN - OPUS4-54016 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 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 U6 - 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 - JOUR A1 - Lutz, C. A1 - Hampel, S. A1 - Beuermann, S. A1 - Turek, T. A1 - Kunz, U. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Fittschen, U. E. A. T1 - Investigation on Vanadium Species Distribution in Nafion™ 117 after Cyclization in a Vanadium Redox Flow Battery N2 - The vanadium redox flow battery (VRFB) is currently a potential candidate for stationary energy storage. A major challenge is the unintended vanadium transport through the separator, which results in a fade of capacity. To overcome this issue, it is necessary to understand the transport processes in the membrane on a more fundamental level. In this work, the vanadium species distribution in Nafion™ 117 after cyclization was investigated. Two membranes, one from a charged VRFB and another from a discharged VRFB, were analyzed using ultraviolet–visible spectroscopy (UV/VIS) and X-ray absorption near edge structure spectroscopy (XANES). Little difference between the two membranes was recognizable according to the UV/VIS results. In comparison, the XANES results showed that the membrane from the charged VRFB contains more V3+ than VO2+, whereas for the discharged case, more VO2+ is present in the membrane. KW - Synchrotron KW - BAMline KW - XANES KW - Vanadium redox flow battery PY - 2021 VL - 64 SP - 1 EP - 8 AN - OPUS4-54144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana T1 - Recent developments of X-ray absorption spectroscopy as analytical tool for biological and biomedical applications N2 - X-ray absorption spectroscopy (XAS), in its various modalities, has gained exponential attention and applicability in the field of biological and biomedical systems. Particularly in this field, challenges like low concentration of analyte or proneness to radiation damage have certainly settle the basis for further analytical developments, when using X-ray based methods. Low concentration calls for higher sensitivity—by increasing the detection limits (DL); while susceptibility for radiation damage requires shorter measurement times and/or cryogenic sample environment possibilities. This manuscript reviews the latest analytical possibilities that make XAS more and more adequate to investigate biological or biomedical systems in the last 5 years. KW - Biological & biomedical applications KW - TXRF-XAS KW - HERFD-XAS KW - RXES KW - Quick-XAS KW - Dispersive-XAS PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-531206 SN - 0049-8246 VL - 51 IS - 3 SP - 1 EP - 10 PB - John Wiley & Sons Ltd AN - OPUS4-53120 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 - Chen, K. A1 - Radu, F. A1 - Weschke, E. A1 - Reinholz, Uwe A1 - de Oliveira Guilherme Buzanich, Ana A1 - Yusenko, Kirill T1 - Al-driven peculiarities of local coordination and magnetic properties in single-phase Alx-CrFeCoNi high-entropy alloys N2 - Modern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision. The revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry. A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account. X-ray magnetic circular dichroism technique employed at L2,3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-Surface region of in situ cleaned fcc-structured Al0.3-CrFeCoNi compared to their bulk values. Extended to nanostructured versions of multicomponent alloys, such studies would bring new insights related to effects of high entropy mixing on low dimensions. KW - X-ray magnetic circular dichroism (XMCD) KW - High-entropy alloys KW - Reverse Monte Carlo KW - Magnetism KW - Element-specific spectroscopy KW - Extended X-ray absorption fine structure (EXAFS) PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-530668 SN - 1998-0124 VL - 15 IS - 6 SP - 4845 EP - 4858 PB - Springer AN - OPUS4-53066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lutz, C. A1 - Breuckmann, M. A1 - Hampel, S. A1 - Kreyenschmidt, M. A1 - Ke, X. A1 - Beuermann, S. A1 - Schafner, K. A1 - Turek, T. A1 - Kunz, U. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Fittschen, U. E. A. T1 - Characterization of Dimeric Vanadium Uptake and Species in Nafion™ and Novel Membranes from Vanadium Redox Flow Batteries Electrolytes N2 - A core component of energy storage systems like vanadium redox flow batteries (VRFB) is the polymer electrolyte membrane (PEM). In this work, the frequently used perfluorosulfonic-acid (PFSA) membrane Nafion™ 117 and a novel poly (vinylidene difluoride) (PVDF)-based Membrane are investigated. A well-known problem in VRFBs is the vanadium permeation through the membrane. The consequence of this so-called vanadium crossover is a severe loss of capacity. For a better understanding of vanadium transport in membranes, the uptake of vanadium ions from electrolytes containing Vdimer(IV–V) and for comparison also V(II), V(III), V(IV), and V(V) by both membranes was studied. UV/VIS spectroscopy, X-ray absorption near edge structure spectroscopy (XANES), total reflection X-ray fluorescence spectroscopy (TXRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and micro X-ray fluorescence spectroscopy (microXRF) were used to determine the vanadium concentrations and the species inside the membrane. The results strongly support that Vdimer(IV–V), a dimer formed from V(IV) and V(V), enters the nanoscopic water-body of Nafion™ 117 as such. This is interesting, because as of now, only the individual ions V(IV) and V(V) were considered to be transported through the membrane. Additionally, it was found that the Vdimer(IV–V) dimer partly dissociates to the individual ions in the novel PVDF-based membrane. The Vdimer(IV–V) dimer concentration in Nafion™ was determined and compared to those of the other species. After three days of equilibration time, the concentration of the dimer is the lowest compared to the monomeric vanadium species. The concentration of vanadium in terms of the relative uptake λ = n(V)/n(SO3 ) are as follows: V(II) [λ = 0.155] > V(III) [λ = 0.137] > V(IV) [λ = 0.124] > V(V) [λ = 0.053] > Vdimer(IV–V) [λ = 0.039]. The results show that the Vdimer(IV–V) dimer Needs to be considered in addition to the other monomeric species to properly describe the transport of vanadium through Nafion™ in VRFBs. KW - MicroXRF KW - VRFB KW - PVDF-based membrane KW - UV/VIS KW - XANES KW - TXRF KW - ICP-OES PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-530676 VL - 11 IS - 8 SP - 576 PB - MDPI AN - OPUS4-53067 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Smekhova, A. A1 - Kuzmin, A. A1 - Siemensmeyer, K. A1 - Abrudan, R. A1 - Reinholz, Uwe A1 - de Oliveira Guilherme Buzanich, Ana A1 - Schneider, M. A1 - Laplanche, G. A1 - Yusenko, Kirill T1 - Inner relaxations in equiatomic single-phase high-entropy Cantoralloy N2 - The superior properties of high-entropy multi-functional materials are strongly connected with their atomic heterogeneity through many different local atomic interactions. The detailed element-specific studies on a local scale can provide insight into the primary arrangements of atoms in multicomponent systems and benefit to unravel the role of individual components in certain macroscopic properties of complex compounds. Herein, multi-edge X-ray absorption spectroscopy combined with reverse Monte Carlo simulations was used to explore a homogeneity of the local crystallographic ordering and specific structure relaxations of each constituent in the equiatomic single-phase facecentered cubic CrMnFeCoNi high-entropy alloy at room temperature. Within the considered fitting approach, all five elements of the alloy were found to be distributed at the nodes of the fcc lattice without any signatures of the additional phases at the atomic scale and exhibit very close statistically averaged interatomic distances (2.54 – 2.55 Å) with their nearest-neighbors. Enlarged structural displacements were found solely for Cr atoms. The macroscopic magnetic properties probed by conventional magnetometry demonstrate no opening of the hysteresis loops at 5 K and illustrate a complex character of the long-range magnetic order after field-assisted cooling in ± 5 T. The observed magnetic behavior is assigned to effects related to structural relaxations of Cr. Besides, the advantages and limitations of the reverse Monte Carlo approach to studies of multicomponent systems like high-entropy alloys are highlighted. 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 absorption near edge structure (XANES) PY - 2022 U6 - https://doi.org/10.1016/j.jallcom.2022.165999 SN - 0925-8388 VL - 920 SP - 1 EP - 31 PB - Elsevier AN - OPUS4-55457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dubey, A. A1 - Hon Keat, C. A1 - Shvartsman, V. A1 - Yusenko, Kirill A1 - Escobar, M. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Hagemann, U. A1 - Kovalenko, S. A1 - Stächler, J. A1 - Lupascu, D. T1 - Mono-, Di-, and Tri-valent Cation Doped BiFe0.95Mn0.05O3 Nanoparticles: Ferroelectric Photocatalysts N2 - The ferroelectricity of multivalent co-doped Bismuth ferrite (BiFeO3; BFO) nanoparticles (NPs) is revealed and utilized for light photocatalysis exploiting their narrow electronic band gap. The photocatalytic activity of ferroelectric photocatalysts BiFe0.95Mn0.05O3 (BFM) NPs and mono-, di-, or tri-valent cations (Ag+, Ca2+, Dy3+; MDT) co-incorporated BFM NPs are studied under ultrasonication and in acidic conditions. We find that such doping enhances the photocatalytic activity of the ferroelectric NPs approximately three times. The correlation of the photocatalytic activity with structural, optical, and electrical properties of the doped NPs is established. The increase of spontaneous polarization by the mono- and tri-valent doping is one of the major factors in enhancing the photocatalytic performance along with other factors such as stronger light absorption in the visible range, low recombination rate of charge carriers and larger surface area of NPs. A-site doping of BFO NPs by divalent elements suppresses the polarization, whereas trivalent (Dy3+) and monovalent (Ag+) cations provide an increase of polarization. The depolarization field in these single domain NPs acts as a driving force to mitigate recombination of the photoinduced charge carriers. KW - Piezoresponse KW - Bismuth Ferrite KW - Nanoparticles KW - Photocatalysis KW - Ferroelectric KW - Polarization PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-557230 SN - 1616-301X SP - 1 EP - 16 PB - Wiley AN - OPUS4-55723 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bruna, F. G. A1 - Prokop, M. A1 - Bystron, T. A1 - Loukrakpam, R. A1 - Melke, J. A1 - Lobo, C. M. S. A1 - Fink, M. A1 - Zhu, M. A1 - Voloshina, E. A1 - Kutter, M. A1 - Hoffmann, H. A1 - Yusenko, Kirill A1 - de Oliveira Guilherme Buzanich, Ana A1 - Röder, B. A1 - Bouzek, K. A1 - Paulus, B. A1 - Roth, C. T1 - Following adsorbed intermediates on a platinum gas diffusion electrode in H3PO3‑containing electrolytes using in situ X‑ray absorption spectroscopy N2 - One of the challenges of high-temperature polymer electrolyte membrane fuel cells is the poisoning of the Pt catalyst with H3PO4. H3PO4 is imbibed into the routinely used polybenzimidazole-based membranes, which facilitate proton conductivity in the temperature range of 120−200 °C. However, when leached out of the membrane by water produced during operation, H3PO4 adsorbs on the Pt catalyst surface, blocking the active sites and hindering the oxygen reduction reaction (ORR). The reduction of H3PO4 to H3PO3, which occurs at the anode due to a combination of a low potential and the presence of gaseous H2, has been investigated as an additional important contributing factor to the observed poisoning effect. H3PO3 has an affinity toward adsorption on Pt surfaces even greater than that of H2PO4 −. In this work, we investigated the poisoning effect of both H3PO3 and H3PO4 using a half-cell setup with a gas diffusion electrode under ambient conditions. By means of in situ X-ray absorption spectroscopy, it was possible to follow the signature of different species adsorbed on the Pt nanoparticle catalyst (H, O, H2PO4 −, and H3PO3) at different potentials under ORR conditions in various electrolytes (HClO4, H3PO4, and H3PO3). It was found that H3PO3 adsorbs in a pyramidal configuration P(OH)3 through a Pt−P bond. The competition between H3PO4 and H3PO3 adsorption was studied, which should allow for a better understanding of the catalyst poisoning mechanism and thus assist in the development of strategies to mitigate this phenomenon in the future by minimizing H3PO3 generation by, for example, improved catalyst design or adapted operation conditions or changes in the electrolyte composition. KW - H3PO4 life cycle KW - XAS KW - In situ coupling KW - High-temperature fuel cells KW - Δμ XANES KW - H3PO3 PY - 2022 U6 - https://doi.org/10.1021/acscatal.2c02630 SN - 2155-5435 VL - 12 IS - 18 SP - 11472 EP - 11484 PB - ACS CY - Washington, DC AN - OPUS4-55815 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Menga, D. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Wagner, F. A1 - Fellinger, Tim-Patrick T1 - Evaluation of the Specific Activity of MNCs and the Intrinsic Activity of Tetrapyrrolic FeN4 Sites for the Oxygen Reduction Reaction N2 - M−N−C electrocatalysts are considered pivotal to replace expensive precious group metal-based materials in electrocatalytic conversions. However, their development is hampered by the limited availability of methods for the evaluation of the intrinsic activity of different active sites, like pyrrolic FeN4 sites within Fe−N−Cs. Currently, new synthetic procedures based on active-site imprinting followed by an ion exchange reaction, e.g. Zn-to-Fe, are producing single-site M−N−Cs with outstanding activity. Based on the same replacement principle, we employed a conservative iron extraction to partially remove the Fe ions from the N4 cavities in Fe−N−Cs. Having catalysts with the same morphological properties and Fe ligation that differ solely in Fe content allows for the facile determination of the decrease in density of active sites and their turn-over frequency. In this way, insight into the specific activity of M−N−Cs is obtained and for single-site catalysts the intrinsic activity of the site is accessible. This new approach surpasses limitations of methods that rely on probe molecules and, together with those techniques, offers a novel tool to unfold the complexity of Fe−N−C catalyst and M−N−Cs in general. KW - Fe-N-C catalysts KW - M-N-C catalysts KW - Fuel Cells PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-567406 SN - 1433-7851 VL - 61 IS - 50 SP - 1 EP - 6 PB - Wiley-VHC AN - OPUS4-56740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Emmerling, Franziska T1 - Time- & spatial-resolved X-ray absorption fine structure (XAFS) spectroscopy in a single-shot – new analytical possibilities for in situ material characterization N2 - A new concept that comprises both time- and lateral-resolved X-ray absorption fine-structure information simultaneously in a single shot is presented. This uncomplicated set-up was tested at the BAMline at BESSY-II (Berlin, Germany). The primary broadband beam was generated by a double multilayer monochromator. The transmitted beam through the sample is diffracted by a convexly bent Si (111) crystal, producing a divergent beam. This, in turn, is collected by either an energy-sensitive area detector, the so-called color X-ray camera, or by an area-sensitive detector based on a CCD camera, in θ-2θ geometry. The first tests were performed with thin metal foils and some iron oxide mixtures. A time resolution of lower than 1 s together with a spatial resolution in one dimension of at least 50 µm is achieved. KW - Time resolution KW - Single-shot XAFS PY - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-370892 SN - 1600-5775 IS - 23 SP - 769 EP - 776 PB - International Union of Crystallography CY - Chester, UK AN - OPUS4-37089 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Emmerling, Franziska ED - de Oliveira Guilherme Buzanich, Ana ED - Strange, R. W. T1 - Time- and spatial-resolved XAFS spectroscopy in a single shot: new analytical possibilities for in situ material characterization N2 - A new concept that comprises both time- and lateral-resolved X-ray absorption fine-structure information simultaneously in a single shot is presented. This uncomplicated set-up was tested at the BAMline at BESSY-II (Berlin, Germany). The primary broadband beam was generated by a double multilayer monochromator. The transmitted beam through the sample is diffracted by a convexly bent Si (111) crystal, producing a divergent beam. This, in turn, is collected by either an energy-sensitive area detector, the so-called color X-ray camera, or by an area-sensitive detector based on a CCD camera, in θ–2θ geometry. The first tests were performed with thin metal foils and some iron oxide mixtures. A time resolution of lower than 1 s together with a spatial resolution in one dimension of at least 50 mm is achieved. KW - Single-shot XAFS KW - Time resolution PY - 2016 UR - http://scripts.iucr.org/cgi-bin/paper?S1600577516003969 U6 - https://doi.org/10.1107/S1600577516003969 SN - 1600-5775 VL - 23 SP - 769 EP - 776 PB - International Union of Crystallography CY - Liverpool, UK AN - OPUS4-35903 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bach, S. A1 - Visnow, E. A1 - Panthöfer, M. A1 - Gorelik, T. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Gulo, A. A1 - Kolb, U. A1 - Emmerling, Franziska A1 - Lind, C. A1 - Tremel, W. T1 - Hydrate networks under mechanical stress – A case study for Co3(PO4)2·8H2O N2 - The nature of the bound water in solids with hydrogen-bonded networks depends not only on temperature and pressure but also on the nature of the constituents. The collapse and reorientation of these network structures determines the stability of hydrated solids and transitions to other crystalline or amorphous phases. Here, we study the mechanochemically induced loss of bound water in Co₃(PO₄)₂·8H₂O and compare this process to the behavior under hydrostatic pressure. The associated phase transition and its kinetics were monitored by X-ray powder diffraction with Synchrotron radiation and quantitative IR spectroscopy. High shearing forces are responsible for the degradation of the hydrogen-bonded network and the concomitant crystalline–amorphous transformation. UV/Vis spectroscopy, extended X-ray absorption spectroscopy (EXAFS), and X-ray absorption near-edge spectroscopy (XANES) provided information about the short-range order in the amorphous solid, and thermal analysis revealed its composition and showed that the moderate charge densities of the Co²⁺ and PO₄³⁻ ions, which make the hydration enthalpy comparable to the binding energy of the counteranions, and the Formation of hydrogen-bonded networks favor multistage crystallization processes associated with the release and uptake of coordinated water. The changes of the Co²⁺ coordination induce a color change from pink to blue; therefore, Co₃(PO₄)₂·8H₂O can be used as an overheat temperature indicator. KW - Mechanochemistry KW - Amorphous materials KW - Hydrates KW - Cobalt KW - Phosphates PY - 2016 U6 - https://doi.org/10.1002/ejic.201501481 SN - 1434-1948 SN - 1099-0682 VL - 2016 IS - 13-14 SP - 2072 EP - 2081 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim, Germany AN - OPUS4-36434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wilke, Manuel A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Rademann, Klaus A1 - Emmerling, Franziska T1 - The structure and in situ synthesis investigation of isomorphic mononuclear molecular metal phenylphosphonates N2 - We describe a fast and effective synthesis for molecular metal phosphonates. Isomorphic compounds [M(II)(HO₃PPh)₂(H₂O₃PPh)₂(H₂O)₂] (M = Mn (1), Co (2), Ni (3); Ph = C₆H₅) were obtained by grinding. The complexes are mononuclear compounds containing neutral and monodeprotonated phenylphosphonic acid and water as ligands. The crystal structures were determined using powder X-ray diffraction (PXRD) data and validated by extended X-ray absorption fine structure (EXAFS) data. Combined synchrotron XRD measurements and Raman spectroscopy were conducted for investigating the reactions in situ. Based on these data, the intermediates were characterized and the formation mechanism was derived. KW - Mechanochemistry KW - Metal phosphonate KW - In situ KW - XRD PY - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-363944 SN - 1477-9226 SN - 1477-9234 SN - 1364-5447 VL - 45 IS - 23 SP - 9460 EP - 9467 AN - OPUS4-36394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bach, S. A1 - Panthöfer, M. A1 - Bienert, Ralf A1 - de Oliveira Guilherme Buzanich, Ana A1 - Emmerling, Franziska A1 - Tremel, W. T1 - Role of water during crystallization of amorphous cobalt phosphate nanoparticles N2 - The transformation of amorphous precursors into crystalline solids and the associated mechanisms are still poorly understood. We illuminate the formation and reactivity of an amorphous cobalt phosphate hydrate precursor and the role of water for its crystallization process. Amorphous cobalt phosphate hydrate nanoparticles (ACP) with diameters of ∼20 nm were prepared in the absence of additives from aqueous solutions at low concentrations and with short reaction times. To avoid the kinetically controlled transformation of metastable ACP into crystalline Co₃(PO₄)₂ × 8H₂O (CPO) its separation must be fast. The crystallinity of ACP could be controlled through the temperature during precipitation. A second amorphous phase (HT-ACP) containing less water and anhydrous Co₃(PO₄)₂ was formed at higher temperature by the release of coordinating water. ACP contains approximately five molecules of structural water per formula unit as determined by thermal analysis (TGA) and quantitative IR spectroscopy. The Co²+ coordination in ACP is tetrahedral, as shown by XANES/EXAFS spectroscopy, but octahedral in crystalline CPO. ACP is stable in the absence of water even at 500 °C. In the wet state, the transformation of ACP to CPO is triggered by the diffusion and incorporation of water into the structure. Quantitative in situ IR analysis allowed monitoring the crystallization kinetics of ACP in the presence of water. KW - Fluorapatite-gelatin nanocomposites KW - Calcium-carbonate KW - Zinc phosphate KW - Crystal-growth KW - Nucleation KW - Polymorphism PY - 2016 U6 - https://doi.org/10.1021/acs.cgd.6b00208 SN - 1528-7483 SN - 1528-7505 VL - 16 IS - 8 SP - 4232 EP - 4239 PB - ACS Publications AN - OPUS4-37616 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wilke, Manuel A1 - Kabelitz, Anke A1 - Gorelik, T. E. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Kolb, U. A1 - Rademann, K. A1 - Emmerling, Franziska T1 - The crystallisation of copper(II) phenylphosphonates N2 - The crystal structures and syntheses of four different copper(II) phenylphosphonates, the monophenylphosphonates α-, β-, and γ-Cu(O3PC6H5)·H2O (α-CuPhPmH (1) β-CuPhPmH (2) and γ-CuPhPmH (3)), and the diphosphonate Cu(HO3PC6H5)2·H2O (CuPhP2mH (4)), are presented. The compounds were synthesized from solution at room temperature, at elevated temperature, under hydrothermal conditions, and mechanochemical conditions. The structures of α-CuPhPmH (1) and CuPhP2mH (4) were solved from powder X-ray diffraction data. The structure of β-CuPhPmH (2) was solved by single crystal X-ray analysis. The structures were validated by extended X-ray absorption fine structure (EXAFS) and DTA analyses. Disorder of the crystal structure was elucidated by electron diffraction. The relationship between the compounds and their reaction pathways were investigated by in situ synchrotron measurements. KW - Mechanochemistry KW - Metal phosphonate KW - In situ PY - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-384217 SN - 1477-9226 SN - 1477-9234 VL - 45 IS - 43 SP - 17453 EP - 17463 PB - The Royal Society of Chemistry AN - OPUS4-38421 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 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 U6 - 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 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Emmerling, Franziska ED - de Oliveira Guilherme Buzanich, Ana T1 - Time- and spatial-resolved X-ray absorption fine structure (XAFS) spectroscopy in a single-shot: new analytical possibilities for in situ material characterization N2 - A new concept that comprises both time- and lateral-resolved X-ray absorption fine-structure information simultaneously in a single shot is presented. This uncomplicated set-up was tested at the BAMline at BESSY-II (Berlin, Germany). The primary broadband beam was generated by a double multilayer monochromator. The transmitted beam through the sample is diffracted by a convexly bent Si (111) crystal, producing a divergent beam. This, in turn, is collected by either an energy-sensitive area detector, the so-called color X-ray camera, or by an area-sensitive detector based on a CCD camera, in θ-2θ geometry. The first tests were performed with thin metal foils and some iron oxide mixtures. A time resolution of lower than 1 s together with a spatial resolution in one dimension of at least 50 µm is achieved. KW - Single-shot XAFS KW - Time resolution KW - Spatial resolution KW - Divergent XAFS PY - 2016 U6 - https://doi.org/10.1107/S1600577516003969 SN - 1600-5775 VL - 23 SP - 769 EP - 776 PB - International Union of Crystallography AN - OPUS4-38370 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich T1 - ´Single-shot´XANES with a Color X-ray Camera (CXC) at the BAMline (BESSY-II) T2 - XAFS 16 CY - Karlsruhe, Germany DA - 2015-08-24 PY - 2015 AN - OPUS4-34042 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fittschen, U. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Böttger, S. A1 - Rosenberg, D. A1 - Menzel, M. A1 - Jensen, W. A1 - Busker, M. A1 - Gotlib, Z. A1 - Radtke, Martin A1 - Riesemeier, Heinrich A1 - Wobrauschek, P. A1 - Streli, C. ED - de Oliveira Guilherme Buzanich, Ana T1 - A setup for synchrotron-radiation-induced total reflection X-ray fluorescence and X-ray absorption near-edge structure recently commissioned at BESSY II BAMline N2 - An automatic sample changer chamber for total reflection X-ray fluorescence (TXRF) and X-ray absorption near-edge structure (XANES) analysis in TXRF geometry was successfully set up at the BAMline at BESSY II. TXRF and TXRF-XANES are valuable tools for elemental determination and speciation, especially where sample amounts are limited (<1 mg) and concentrations are low (ng ml⁻¹ to μg ml⁻¹). TXRF requires a well defined geometry regarding the reflecting surface of a sample carrier and the synchrotron beam. The newly installed chamber allows for reliable sample positioning, remote sample changing and evacuation of the fluorescence beam path. The chamber was successfully used showing accurate determination of elemental amounts in the certified reference material NISTwater 1640. Low limits of detection of less than 100 fg absolute (10 pg ml⁻¹) for Ni were found. TXRF-XANES on different Re species was applied. An unknown species of Re was found to be Re in the +7 oxidation state. KW - TXRF KW - TXRF-XANES KW - Sample changer KW - BAMline KW - Re-XANES PY - 2016 U6 - https://doi.org/10.1107/S1600577516001995 SN - 1600-5775 VL - 23 IS - 3 SP - 820 EP - 824 PB - International Union of Crystallography AN - OPUS4-38656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hachmöller, O. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Aichler, M. A1 - Radtke, Martin A1 - Dietrich, D. A1 - Schwamborn, K. A1 - Lutz, L. A1 - Werner, M. A1 - Sperling, M. A1 - Walch, A. A1 - Karst, U. T1 - Elemental bioimaging and speciation analysis for the investigation of Wilsons disease using μXRF and XANES N2 - A liver biopsy specimen from a Wilson’s disease (WD) patient was analyzed by means of micro-X-ray fluorescence (mXRF) spectroscopy to determine the elemental distribution. First, bench-top mXRF was utilized for a coarse scan of the sample under laboratory conditions. The resulting distribution maps of copper and iron enabled the determination of a region of interest (ROI) for further analysis. In order to obtain more detailed elemental information, this ROI was analyzed by synchrotron radiation (SR)-based mXRF with a beam size of 4 mm offering a resolution at the cellular level. Distribution maps of additional elements to copper and iron like zinc and manganese were obtained due to a higher sensitivity of SR-mXRF. In addition to this, X-ray absorption near edge structure spectroscopy (XANES) was performed to identify the oxidation states of copper in WD. This speciation analysis indicated a mixture of copper(I) and copper(II) within the WD liver tissue. KW - progressive hepatolenticular degeneration KW - mXRF Micro-X-ray fluorescence spectroscopy KW - XANES X-ray absorption near edge structure spectroscopy PY - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-360811 SN - 1756-5901 SN - 1756-591X PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-36081 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-512707 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 - Wahl, S. A1 - El-Refaei, S. M. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Amsalem, P. A1 - Lee, K.-S. A1 - Koch, N. A1 - Doublet, M.-L. A1 - Pinna, N. T1 - Zn0.35Co0.65O – A Stable and highly active oxygen evolution catalyst formed by zinc leaching and tetrahedral coordinated cobalt in wurtzite structure N2 - To arrive to sustainable hydrogen-based energy solutions, the understanding of water-splitting catalysts plays the most crucial role. Herein, state-of-the-art hypotheses are combined on electrocatalytic active metal sites toward the oxygen evolution reaction (OER) to develop a highly efficient catalyst based on Earth-abundant cobalt and zinc oxides. The precursor catalyst Zn0.35Co0.65O is synthesized via a fast microwaveassisted approach at low temperatures. Subsequently, it transforms in situ from the wurtzite structure to the layered γ-Co(O)OH, while most of its zinc leaches out. This material shows outstanding catalytic Performance and stability toward the OER in 1 m KOH (overpotential at 10 mA cm−2 ηinitial = 306 mV, η98 h = 318 mV). By comparing the electrochemical results and ex situ analyses to today’s literature, clear structureactivity correlations are able to be identified. The findings suggest that coordinately unsaturated cobalt octahedra on the surface are indeed the active centers for the OER. KW - Oxygen Evolution Catalyst KW - XAFS KW - Oxygen evolution reaction (OER) KW - Cobalt and zinc oxides PY - 2019 U6 - https://doi.org/10.1002/aenm.201900328 SN - 1614-6832 SN - 1614-6840 VL - 9 IS - 20 SP - 1900328,1 EP - 10 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-48200 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lumpe, H. A1 - Menke, A. 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. J. 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 - Lanthanides KW - Structural Analysis KW - Separation PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-510821 SN - 0947-6539 VL - 26 SP - 1 EP - 8 PB - WILEY-VCH Verlag GmbH & co. KGaA AN - OPUS4-51082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radtke, Martin A1 - Buzanich, Günter A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Scharf, O. A1 - Scholz, Philipp A1 - Guerra, M.F. T1 - Double Dispersive X-Ray Fluorescence (D2XRF) based on an Energy Dispersive pnCCD detector for the detection of platinum in gold N2 - With the aim of improving limits of detection (LOD) of trace elements in a matrix with adjacent fluorescence energies, a simple double dispersive X-ray fluorescence detection system (D2XRF) was constructed to operate at the beamlines BAMline and the mySpot @ BESSY II. This system is based on the combination of a crystal analyzer with an energy resolving single photon counting pnCCD. Without further collimators, the efficient suppression of the background by the pnCCD and the good energy resolution of the crystal results in improved LOD. In first order reflections, an energy resolution of 13 eV for Cu Kα was reached, and an energy range of 1 keV was covered in one shot. This new system was applied to the detection of platinum (Pt) in gold leaves with a LOD of 0.9 mg/kg, which is the lowest attained by totally non-destructive methods nowadays. The presence of Pt in gilded objects from Abydos and Byzantine mosaics provides vital information, as it indicates the alluvial origin of the gold for these examples. KW - Platinum Wavelength dispersive D2XRF KW - Gold Synchrotron XRF PY - 2016 U6 - https://doi.org/10.1016/j.microc.2015.10.039 VL - 125 SP - 56 EP - 61 PB - Elsevier Science CY - Amsterdam AN - OPUS4-35777 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 - Schoeckel, A. A1 - Roth, C. T1 - A combined in-situ XAS-DRIFTS study unraveling adsorbate induced changes on the Pt nanoparticle structure 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, Dl X-ray Absorption Near Edge Structure analysis (Dl 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 PtAPt 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 PtACO to PtAO. Reoxidation was clearly assigned to strong metal support interaction from the SiO2 support. KW - X-ray absorption spectroscopy KW - DRIFTS KW - XANES KW - CO adsorption KW - Platinum KW - Strong metal support interaction KW - Silica support KW - Adsorbates KW - Infrared spectroscopy PY - 2016 U6 - https://doi.org/10.1016/j.jcat.2016.03.034 IS - 339 SP - 57 EP - 67 PB - Elsevier Inc. CY - Philadelphia, Pennsylvania, USA AN - OPUS4-35815 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kabelitz, Anke A1 - de Oliveira Guilherme Buzanich, Ana A1 - Joester, Maike A1 - Reinholz, Uwe A1 - Radtke, Martin A1 - Bienert, Ralf A1 - Schulz, K. A1 - Schmack, R. A1 - Kraehnert, R. A1 - Emmerling, Franziska T1 - Time-resolved in situ studies on the formation mechanism of iron oxide nanoparticles using combined fast-XANES and SAXS N2 - The reaction of iron chlorides with an alkaline reagent is one of the most prominent methods for the synthesis of iron oxide nanoparticles. We studied the particle formation mechanism using triethanolamine as reactant and stabilizing agent. In situ fast-X-ray absorption near edge spectroscopy and small-angle X-ray scattering provide information on the oxidation state and the structural information at the same time. In situ data were complemented by ex situ transmission electron microscopy, wide-angle X-ray scattering and Raman analysis of the formed nanoparticles. The formation of maghemite nanoparticles (γ-Fe2O3) from ferric and ferrous chloride was investigated. Prior to the formation of these nanoparticles, the formation and conversion of intermediate phases (akaganeite, iron(II, III) hydroxides) was observed which undergoes a morphological and structural collapse. The thus formed small magnetite nanoparticles (Fe3O4) grow further and convert to maghemite with increasing reaction time. KW - oxidation state KW - structural information KW - maghemite PY - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-351376 SN - 1466-8033 VL - 17 IS - 44 SP - 8463 EP - 8470 CY - London, UK AN - OPUS4-35137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wahl, S. A1 - El-Refaei, S. M. A1 - Amsalem, P. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Koch, N. A1 - Pinna, N. T1 - Operando diffuse reflectance UV-vis spectroelectrochemistry for investigating oxygen evolution electrocatalysts N2 - The characterization of the active structure of water-splitting catalysts is crucial to evolve to a sustainable energy future based on hydrogen. Such information can only be obtained by operando methods. We present a diffuse reflectance UV-vis (DRUV) spectroelectrochemical study that allows tracking the changes of solid oxygen evolution catalysts under working conditions. The versatility of our approach is demonstrated on two cobalt-containing catalysts, Zn0.35Co0.65O and CoAl2O4. The changes the catalysts undergo during the oxygen evolution reaction can be tracked by probing the electronic structure using UV-vis spectroscopy. These findings are compared to ex situ analyses, which support the assignments of the structures stabilized under different potentials. Thus, structure–activity correlations can be proposed, and deeper insights into the catalytically active structures can be obtained. KW - EXAFS PY - 2020 U6 - https://doi.org/10.1039/c9cy02329a VL - 10 IS - 2 SP - 517 EP - 528 PB - Royal Society of Chemistry AN - OPUS4-50468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulow, Anicó A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Streli, C. A1 - Radtke, Martin T1 - On the way to full-field X-ray fluorescence spectroscopy imaging with coded apertures N2 - Imaging with X-rays is a challenging field, due to the optical properties of X-rays. The fabrication of appropriate optics is usually expensive and requires an elaborate manufacturing process. One simpler and less expensive possibility of imaging high energy radiation is coded aperture imaging, a technique well established in astrophysics and also used in nuclear medicine or radiation detection, e.g., for nuclear decommissioning. Our aim is to adapt coded aperture imaging for X-ray fluorescence spectroscopy in the nearfield. In this work we show theoretical considerations and preliminary simulations of Image formation through a coded aperture and three different reconstruction methods to prepare the experiments. We used a new mask based on an inverted modified uniformly redundant array (MURA) that could be used for the construction of a decoding mask for all investigated geometrical arrangements. The most commonly used reconstruction method, convoluting the detected image with a Decoding mask, does not always deliver satisfactory results. This is more noticeable for small distances between the object, mask and detector. Hence, we developed two new reconstruction methods, one based on iterative algebraic optimization and another one based on a genetic algorithm. Both show good performance even in those cases where the convolution method fails. This provides a basis for further investigations of the ideal parameters for near field coded aperture imaging and refinements of the algorithms. We performed first measurements with a coded aperture at the BAMline at BESSY II and could successfully reconstruct a test object from the obtained recorded images. KW - X-ray fluorescence spectroscopy KW - Coded aperture KW - Imaging KW - Iterative reconstruction PY - 2020 U6 - https://doi.org/10.1039/c9ja00232d VL - 35 IS - 2 SP - 347 EP - 356 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-50459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heilmann, Maria A1 - Kulla, Hannes A1 - Prinz, Carsten A1 - Bienert, Ralf A1 - Reinholz, Uwe A1 - de Oliveira Guilherme Buzanich, Ana A1 - Emmerling, Franziska T1 - Advances in Nickel Nanoparticle Synthesis via Oleylamine Route N2 - Nickel nanoparticles are an active research area due to their multiple applications as catalysts in different processes. A variety of preparation techniques have been reported for the synthesis of these nanoparticles, including solvothermal, microwave-assisted, and emulsion techniques. The well-studied solvothermal oleylamine synthesis route comes with the drawback of needing standard air-free techniques and often space-consuming glassware. Here, we present a facile and straightforward synthesis method for size-controlled highly monodisperse nickel nanoparticles avoiding the use of, e.g., Schlenk techniques and space-consuming labware. The nanoparticles produced by this novel synthetic route were investigated using small-angle X-ray scattering, transmission electron microscopy, X-ray diffraction, and X-ray spectroscopy. The nanoparticles were in a size range of 4–16 nm, show high sphericity, no oxidation, and no agglomeration after synthesis. KW - Nanoparticle synthesis KW - Nickel nanoparticles KW - SAXS KW - TEM KW - XAS PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-507531 VL - 10 IS - 4 SP - 713 PB - MDPI AN - OPUS4-50753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gao, S. A1 - Hou, J. A1 - Deng, Z. A1 - Wang, T. A1 - Beyer, Sebastian A1 - de Oliveira Guilherme Buzanich, Ana A1 - Richardson, J. J. A1 - Rawal, A. A1 - Seidel, R. A1 - Zulkifli, M. Y. A1 - Li, W. A1 - Bennett, T. D. A1 - Cheetham, A. K. A1 - Liang, K. T1 - Improving the Acidic Stability of Zeolitic Imidazolate Frameworks by Biofunctional Molecules N2 - Zeolitic imidazolate frameworks (ZIFs) have been widely investigated for their use in separation, gas adsorption, catalysis, and biotechnology. Their practical applications, however, can be hampered by their structural instability in humid acidic conditions. Here, guided by density functional theory calculations, we demonstrate that the acidic stability of two polymorphic ZIFs (i.e., ZIF-8 and ZIF-L) can be enhanced by the incorporation of functional groups on polypeptides or DNA. A range of complementary synchrotron investigations into the local chemical structure and bonding environment suggest that the enhanced acidic stability arises from the newly established coordinative interactions between the Zn centers and the inserted carboxylate (for polypeptides) or phosphate (for DNA) groups, both of which have lower pKas than the imidazolate ligand. With functional biomolecular homologs (i.e., enzymes), we demonstrate a symbiotic stability reinforcement effect, i.e., the encapsulated biomolecules stabilize the ZIF matrix while the ZIF exoskeleton protects the enzyme from denaturation. KW - Zeolitic Imidazolate Frameworks KW - Biofunctional Molecules KW - X-ray Absorption Spectroscopy PY - 2019 U6 - https://doi.org/10.1016/j.chempr.2019.03.025 VL - 5 IS - 6 SP - 1597 EP - 1608 PB - Elsevier Inc. AN - OPUS4-48702 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-517420 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 - 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 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 U6 - 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 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 U6 - 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 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 U6 - 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 - Kulow, Anicó A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Hampel, S. A1 - Fittschen, U.E.A. A1 - Streli, C. A1 - Radtke, Martin T1 - Comparison of three reconstruction methods based on deconvolution, iterative algorithm and neural network for X-ray fluorescence imaging with coded apertures N2 - X-ray imaging methods are used in many fields of research, as they allow a non-destructive Investigation of the elemental content of various samples. As for every imaging method, for X-ray imaging the optics are of crucial importance. However, these optics can be very expensive and laborious to build, as the requirements on surface roughness and precision are extremely high. Angles of reflection and refraction are often in the range of a few mrad, making a compact design hard to achieve. In this work we present a possibility to simplify X-ray imaging. We have adapted the coded aperture method, a high energy radiation imaging method that has its origins in astrophysics, to full field X-ray fluorescence imaging. In coded aperture imaging, an object is projected through a known mask, the coded aperture, onto an area sensitive detector. The resulting image consists of overlapping projections of the object and a reconstruction step is necessary to obtain the information from the recorded image. We recorded fluorescence images of different samples with an energy-dispersive 2D detector (pnCCD) and investigated different reconstruction methods. With a small coded aperture with 12 holes we could significantly increase the count rate compared to measurements with a straight polycapillary optic. We show that the reconstruction of two different samples is possible with a deconvolution approach, an iterative algorithm and a neural network. These results demonstrate that X-ray fluorescence imaging with coded apertures has the potential to deliver good results without scanning and with an improved count rate, so that measurement times can be shortened compared to established methods. KW - X-ray fluorescence imaging KW - Coded apertures KW - Imaging KW - Elemental mapping KW - Image reconstruction PY - 2020 U6 - https://doi.org/10.1039/d0ja00146e VL - 35 IS - 7 SP - 1423 EP - 1434 PB - Royal Society of Chemistry CY - United Kingdom AN - OPUS4-51518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grengg, C. A1 - Gluth, Gregor A1 - Mittermayr, F. A1 - Ukrainczyk, N. A1 - Bertmer, M. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Leis, A. A1 - Dietzel, M. T1 - Deterioration mechanism of alkali-activated materials in sulfuric acid and the influence of Cu: A micro-to-nano structural, elemental and stable isotopic multi-proxy study N2 - In this study, a multi-proxy approach combining 29Si, 27Al and 1H MAS-NMR, FEG-EPMA, XANES at the Cu K-edge and XRD analytics with hydrochemical tools such as ICP-OES analyses, oxygen-isotope signatures, and thermodynamic modelling was applied to K-silicate-activated metakaolin specimens - with and without CuSO4·5H2O addition - exposed to sulfuric acid at pH = 2 for 35 days. The results revealed a multistage deterioration mechanism governed by (i) acid diffusion, (ii) leaching of K-A-S-H, (iii) microstructural damage related to precipitation of expansive (K,Ca,Al)-sulfate-hydrate phases (iv) complete dissolution of the K-A-S-H framework, (v) and formation of silica gel in the outermost corroded regions. Copper ions were mainly located in layered spertiniite-chrysocolla-like phases in the as-cured materials. The results demonstrate an overall negative effect of Cu addition on chemical material durability, implying that the reported higher durability of Cu-doped AAM in biocorrosion environments can be best explained by bacteriostatic effects. KW - Alkali-activated materials KW - Acid resistance KW - Microbially induced corrosion KW - MIC PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-520567 SN - 0008-8846 VL - 142 SP - 1 EP - 15 PB - Elsevier CY - Oxford AN - OPUS4-52056 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szczerba, Wojciech A1 - Schneider, M. A1 - Żukrowski, J. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Riesemeier, Heinrich A1 - Sikora, M. A1 - Mandel, K. T1 - Spectroscopic Study of the Role of Metal Ions in the Adsorption Process of Phosphate in Nanoscaled Adsorbers Based on Metal (Zn/ Fe/Zr) Oxyhydroxides N2 - Currently great effort is made to find materials and technologies for the recycling of phosphate from wastewater. Herein, we present an in-depth study of the Phosphate adsorption mechanism of a promising adsorber material, a Zn−Fe−Zr oxyhydroxide-based nanostructured precipitate. The behavior of the multicomponent nanomaterial, consisting of both crystalline and amorphous parts, is investigated via X-ray absorption fine structure spectroscopy and Mössbauer spectroscopy, revealing the importance of the nanostructured composition for the phosphate adsorption. We found evidence that adsorption takes place especially in the vicinity of iron sites in the amorphous part of the material. KW - Zn-Fe-Zr nanoparticles KW - Adsorption of phosphate KW - XAFS KW - Catalysis PY - 2017 U6 - https://doi.org/10.1021/acs.jpcc.7b04773 SN - 1932-7447 VL - 121 IS - 45 SP - 25033 EP - 25042 PB - ACS Publications AN - OPUS4-43348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rauwolf, M. A1 - Turyanskaya, A. A1 - Roschger, A. A1 - Prost, J. A1 - Simon, R. A1 - Scharf, O. A1 - Radtke, Martin A1 - Schoonjans, Tom A1 - de Oliveira Guilherme Buzanich, Ana A1 - Klaushofer, K. A1 - Wobrauschek, P. A1 - Hofstaetter, J. G. A1 - Roschger, P. A1 - Streli, C. T1 - Synchrotron radiation micro X-ray fluorescence spectroscopy of thin structures in bone samples: comparison of confocal and color X-ray camera setups N2 - In the quest for finding the ideal synchrotron-radiation-induced imaging method for the investigation of trace element distributions in human bone samples, experiments were performed using both a scanning confocal synchrotron radiation micro X-ray fluorescence (SR-mXRF) (FLUO beamline at ANKA) setup and a full-field color X-ray camera (BAMline at BESSY-II) setup. As zinc is a trace element of special interest in bone, the setups were optimized for its detection. The setups were compared with respect to count rate, required measurement time and spatial resolution. It was demonstrated that the ideal method depends on the element of interest. Although for Ca (a major constituent of the bone with a low energy of 3.69 keV for its K alpha XRF line) the color X-ray camera provided a higher resolution in the plane, for Zn (a trace element in bone) only the confocal SR-µXRF setup was able to sufficiently image the distribution. KW - Synchrotron KW - BAMline KW - BESSY KW - XRF KW - X-ray Color Camera PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-391944 SN - 1600-5775 VL - 24 SP - 307 EP - 311 PB - International Union of Crystallography AN - OPUS4-39194 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Akhmetova, Irina A1 - Schuzjajew, K. A1 - Wilke, M. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Rademann, K. A1 - Roth, C. A1 - Emmerling, Franziska T1 - Synthesis, characterization and in situ monitoring of the mechanochemical reaction process of two manganese(II)-phosphonates with N-containing ligands N2 - Two divalent manganese aminophosphonates, manganese mono (nitrilotrimethylphosphonate) (MnNP3) and manganese bis N-(carboxymethyl)iminodi(methylphosphonate)) (Mn(NP2AH)2), have been prepared by mechanochemical synthesis and characterized by powder X-ray diffraction (PXRD). The structure of the novel compound Mn(NP2AH)2 was determined from PXRD data. MnNP3 as well as Mn(NP2AH)2 exhibits a chain-like structure. In both cases, the manganese atom is coordinated by six oxygen atoms in a distorted octahedron. The local coordination around Mn was further characterized by extended X-ray absorption fine structure. The synthesis process was followed in situ by synchrotron X-ray diffraction revealing a three-step reaction mechanism. The asprepared manganese(II) phosphonates were calcined on air. All samples were successfully tested for their suitability as catalyst material in the oxygen evolution reaction. KW - Mechanochemistry KW - In situ KW - XRD PY - 2018 U6 - https://doi.org/10.1007/s10853-018-2608-6 SN - 0022-2461 SN - 1573-4803 VL - 53 IS - 19 SP - 13390 EP - 13399 PB - Springer Science + Business Media B.V. AN - OPUS4-45673 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manso, M. A1 - Pessanha, S. A1 - Guerra, M. A1 - Reinholz, Uwe A1 - Afonso, C. A1 - Radtke, Martin A1 - Lourenco, H. A1 - Carvalho, M. L. A1 - de Oliveira Guilherme Buzanich, Ana T1 - Assessment of Toxic Metals and Hazardous Substances in Tattoo Inks Using Sy-XRF, AAS, and Raman Spectroscopy N2 - Synchrotron radiation X-ray fluorescence spectroscopy, in conjunction with atomic absorption and Raman spectroscopy, was used to analyze a set of top brand tattoo inks to investigate the presence of toxic elements and hazardous substances. The Cr, Cu, and Pb contents were found to be above the maximum allowed levels established by the Council of Europe through the resolution ResAP(2008)1 on requirements and criteria for the safety of tattoos and permanent makeup. Raman analysis has revealed the presence of a set of prohibited substances mentioned in ResAP(2008)1, among which are the pigments Blue 15, Green 7, and Violet 23. Other pigments that were identified in white, black, red, and yellow inks are the Pigment White 6, Carbon Black, Pigment Red 8, and a diazo yellow, respectively. The present results show the importance of regulating tattoo ink composition. KW - Synchrotron KW - Tattoo inks KW - XRF KW - Toxic metals KW - Hazardous substances PY - 2019 U6 - https://doi.org/10.1007/s12011-018-1406-y VL - 187 IS - 2 SP - 596 EP - 601 PB - Springer AN - OPUS4-47369 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana T1 - Hard X-ray spectroscopy and imaging at the BAMline and MySpot beamlines at BESSY II (Berlin, Germany) N2 - Overview of the X-ray based analytical methods conducted at the BAMline and µSpot Beamline for structure analysis. T2 - Pccr2 + AfLS conference CY - Accra, Ghana DA - 29.01.2019 KW - X-ray spectroscopy KW - Synchrotron KW - Beamline KW - Material characterization PY - 2019 AN - OPUS4-47319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulow, Anicó A1 - Witte, S. A1 - Beyer, S. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, H. A1 - Streli, C. T1 - A new experimental setup for time- and laterally-resolved X-ray absorption fine structure spectroscopy in a 'single shot' N2 - In this work, a new setup for dispersive XAFS measurements is presented. This reproducible and scanningfree setup yields both time- and laterally-resolved XAFS experiments in a ‘single-shot’. It allows a straightforward adjustment for probing different elements covering many relevant applications in materials science. An incoming energetic broadband beam is diffracted by a Si (111) crystal after passing through the sample and collected by an area sensitive detector. Depending on the energy range of the incoming beam, XANES and/or EXAFS spectra can be recorded with a time resolution down to 1 s. The feasibility of this setup was demonstrated at the BAMline at BESSY II (Berlin, Germany) with reference Fe and Cu foils and the results are hereby presented and discussed. Additionally, an application where time resolution on the second scale is required is briefly evaluated. The presented example concerns studying early stages of zinc(II)2-methylimidazolate (ZIF-8) crystallization. This is particularly important for biomedical applications. KW - X-ray spectroscopy KW - X-ray absorption fine structure KW - Time-resolved KW - Laterally-resolved KW - Experimental setup PY - 2019 U6 - https://doi.org/10.1039/c8ja00313k SN - 0267-9477 SN - 1364-5544 VL - 34 IS - 1 SP - 239 EP - 246 PB - Royal Society of Chemistry CY - London AN - OPUS4-47207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana T1 - Career talk & lab tour - Working at BESSY II, a large scale research facility in Adlershof N2 - What exactly does a postdoc do at a research institute? What scientific questions does he or she want to address? What is their daily work routine? During our regular Lab Tours, female postdocs provide insight into their jobs. They also tell us about their career path: How did they get there? And what do they envision for their professional future? This time, Dr. Ana Guilherme Buzanich, a scientist from the Structure Analysis division at the Bundesanstalt für Materialforschung und -prüfung (BAM), will give an overview of her Research areas. She works at the electron storage ring BESSY-II where she conducts experiments at two hard X-ray beamlines (BAMline and µSpot). The tour includes a guided visit of the research facility. T2 - Lab Tour & Career Talk, WiNS CY - Berlin, Germany DA - 11.02.2019 KW - Women in STEM KW - X-ray Spectroscopy KW - Synchrotron KW - Beamline KW - Material characterization PY - 2019 AN - OPUS4-47418 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Rui A1 - Russo, Patrícia A. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Jeon, Taeyeol A1 - Pinna, Nicola T1 - Hybrid organic–inorganic transition-metal phosphonates as precursors for water oxidation electrocatalysts N2 - Efficient water oxidation catalysts are required for the development of water splitting technologies. Herein, the synthesis of layered hybrid NiFephenylphosphonate compounds from metal acetylacetonate precursors and phenylphosphonic acid in benzyl alcohol, and their Oxygen evolution reaction performance in alkaline medium, are reported. The hybrid particles are formed by inorganic layers of NiO6 and FeO6 distorted octahedra separated by bilayers of the organic group, and template the Formation in situ of NiFe hydroxide nanosheets of sizes between 5 and 25 nm and thicknesses between 3 and 10 nm. X-ray absorption spectroscopy measurements suggest that the hybrid also acts as a template for the local structure of the metal sites in the active catalyst, which remain distorted after the transformation. Optimum electrocatalytic activity is achieved with the hybrid compound with a Fe content of 16%. The combination of the synergistic effect between Ni and Fe with the structural properties of the hybrid results in an efficient catalyst that generates a current density of 10 mA cm−2 at an overpotential of 240 mV, and also in a stable catalyst that operates continuously at low overpotentials for 160 h. KW - Water oxydation catalysis KW - EXAFS PY - 2017 U6 - https://doi.org/10.1002/adfm.201703158 SN - 1616-301X SN - 1616-3028 VL - 27 IS - 40 SP - Article 1703158, 1 EP - 11 PB - WILEY-VCH Verlag CY - Weinheim AN - OPUS4-42783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wintzheimer, S. A1 - Szczerba, Wojciech A1 - de Oliveira Guilherme Buzanich, Ana A1 - Kashiwaya, S. A1 - Klein, A. A1 - Jaegermann, W. A1 - Toupance, T. A1 - Shmeliov, A. A1 - Nicolosi, V. A1 - Heuzé, K. A1 - Mandel, K. A1 - Dembski, S. T1 - Discovering the determining parameters for the photocatalytic activity of TiO2 colloids based on an anomalous dependence on the specific surface area N2 - The photocatalytic (PC) performance of titanium dioxide (TiO2) nanoparticles strongly depends on their specific surface, the presence of crystal defects, their crystal phase, and the exposed crystal facets. In order to understand which of these factors contributes most significantly to the PC activity of TiO2 colloids, all of them have to be individually analyzed. This study entails the synthesis of five anatase nanocrystal samples. By maintaining the same reactant ratios as well as hydrothermal sol–gel synthesis route and only varying the autoclaving time or temperature, different crystallite sizes are obtained under comparable experimental conditions. A decrease in PC performance with increase in specific surface area is found. Such an unexpected counterintuitive result establishes the basis for a better understanding of the crucial factors that ultimately determine the PC activity. These are investigated by studying nanocrystals bulk and surface structure and morphology using a selection of complementary analysis methods (X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), X-ray diffraction (XRD)…). It is found that a change in the nanocrystal morphology from an equilibrium state truncated tetragonal bipyramid to a more elongated rod-like structure accompanied by an increase in oxygen vacancies is responsible for an augmented PC activity of the TiO2 nanocrystals. KW - Ti-based colloids KW - Photocatalysis KW - Spectroscopy KW - XAFS PY - 2018 U6 - https://doi.org/10.1002/ppsc.201800216 SN - 0934-0866 SN - 1521-4117 VL - 35 IS - 9 SP - 1800216, 1 EP - 10 PB - Wiley Online Library AN - OPUS4-46068 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Al-Terkawi, Abdal-Azim A1 - Scholz, G. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinsch, Stefan A1 - Kemnitz, E. A1 - Emmerling, Franziska T1 - Ca- and Sr- tetrafluoroisophthalates: mechanochemical synthesis, characterization, and ab initio structure determination N2 - New fluorinated coordination polymers were prepared mechanochemically by milling the alkaline earth metal hydroxides MII(OH)2·xH2O (MII: Ca, Sr) with tetrafluoroisophthalic acid (H2mBDC-F4). The structures of [{Ca(mBDC-F4)(H2O)2}·H2O] and [{Sr(mBDC-F4)(H2O)2}·H2O] were determined based on ab initio calculations and their powder X-ray diffraction (PXRD) data. The compounds are isomorphous and crystallize in the orthorhombic space group P212121. The determined structures were validated by using extended X-ray absorption (EXAFS) data. The new materials were thoroughly characterized using elemental analysis, thermal analysis, magic angle spinning NMR, and attenuated total reflection-infrared spectroscopy. Further characterization methods such as BET, dynamic vapor sorption, and scanning electron microscopy imaging were also used. Our investigations indicate that mechanochemistry is an efficient method for preparing such materials. KW - Mechanochemistry KW - In situ KW - XRD KW - Coordination polymers PY - 2017 UR - http://pubs.rsc.org/-/content/articlehtml/2017/dt/c7dt00734e U6 - https://doi.org/10.1039/c7dt00734e VL - 46 IS - 18 SP - 6003 EP - 6012 AN - OPUS4-41516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana A1 - Kulow, Anicó A1 - Beyer, Sebastian A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich T1 - S2XAFS: Time-resolved X-ray absorption spectroscopy in a ‘single-shot’ – First in situ applications N2 - The newly developed EXAFS set-up comprises both time- and spatially-resolved EXAFS information simultaneously in a single-shot. This facile, stable and scanningless set-up was tested at the BAMline @ BESSY-II (Berlin, Germany). The pri-mary broadband beam is generated by a filter/X-ray-mirror combination (bandpass). The transmitted beam through the sample is diffracted by a convexly bent Si (111) crystal, producing a divergent beam. This, in turn, is collected by an area sensitive detector, in a theta - 2 theta geometry. The first in situ measurements were successfully carried out and hereby presented. The case-study deals with research on Zn-based Metal-Organic-Frameworks (MOFs) that have potential for medi-cal/pharmaceutical applications. This hot topic of MOF research targets encapsulation of therapeutically relevant bio-macromolecules (e.g. Enzymes) for drug delivery applications. Questions regarding the influence of proteins on the coor-dination of Zn during MOF crystal growth and within the final MOF can be answered with this new setup. We were able to track structural changes within a 1s time resolution. T2 - CSI XL Conference CY - Pisa, Italy DA - 12.06.2017 KW - Single-shot EXAFS KW - In situ characterization KW - Biomedical applications PY - 2017 AN - OPUS4-40683 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abad Andrade, Carlos Enrique A1 - Florek, S. A1 - Becker-Ross, H. A1 - Huang, M.-D. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Lippitz, Andreas A1 - Hodoroaba, Vasile-Dan A1 - Schmid, Thomas A1 - Heinrich, Hans-Joachim A1 - Recknagel, Sebastian A1 - Jakubowski, Norbert A1 - Panne, Ulrich T1 - Zirconium permanent modifiers for graphite furnaces used in absorption spectrometry: understanding their structure and mechanism of action N2 - The mechanism of action of zirconium permanent modifiers on graphite surfaces was investigated in order to understand its influence on the analytical signal in atomic and molecular absorption spectrometry (AAS/MAS). For this, the molecule formation of CaF was studied, which is used for the indirect analytical determination of fluorine in high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). The kinetics of this reaction was established by monitoring its molecular spectrum at different atomisation temperatures. An Arrhenius plot showed a pseudo-first order reaction with respect to fluorine (n = 1). An intermediate state was isolated, and its structure was elucidated by spectroscopic methods: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEMEDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES and EXAFS), and Raman microspectroscopy. We propose here a mechanism, where ZrO2 acts as a heterogeneous catalyst: after a pyrolytic step, an intermediate state of ZrO(OCaF) is activated, and at higher temperatures, CaF(g) is released from the zirconium-coated graphite surface. No evidence of the formation of zirconium carbide was found. Consequently, as the CaF formation is catalysed by a heterogeneous catalyst, surface modifications with ZrO2 nanoparticles and ZrO xerogels were investigated in order to increase the surface area. Their influence was evaluated in the molecule formation of CaF, CaCl, CaBr, and CaI. Graphite furnace modification with zirconium oxide nanoparticles proves to be the best choice for fluorine analysis with a signal enhancement of more than eleven times with respect a non-coated graphite furnace. However, the influence of zirconium modifications in the analytical signals of Cl, and I is lower than the F signals or even negative in case of the Br. Understanding zirconium modifiers as heterogeneous catalysts offers a new perspective to AAS and MAS, and reveals the potential of surface analytical methods for development of improved permanent modifiers and graphite furnace coatings. KW - Zirconium KW - HR-CS-MAS KW - Graphite furnace KW - Nanoparticles KW - Xerogel KW - Calcium monofluoride KW - Absorption spectrometry PY - 2018 UR - https://pubs.rsc.org/en/content/articlelanding/2018/ja/c8ja00190a U6 - https://doi.org/10.1039/C8JA00190A SN - 0267-9477 VL - 33 IS - 12 SP - 2034 EP - 2042 PB - Royal Society of Chemistry AN - OPUS4-46775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Oliveira Guilherme Buzanich, Ana A1 - Emmerling, Franziska T1 - Structure analytics with Hard X-rays at the BAMline and µSpot beamlines N2 - An overview of the research areas at the structure analysis division is given. Specifically the in situ characterization of dynamic processes with hard X-ray diffraction and absorption spectroscopy at the BAMline and µSpot beamlines (BESSY-II). T2 - BAM-IFW Workshop CY - Dresden, Germany DA - 28.03.2019 KW - Structure analysis KW - X-ray Spectroscopy KW - Synchrotron KW - Beamline KW - Material characterization PY - 2019 AN - OPUS4-47695 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 A. L. 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-567659 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 - Cakir, Cafer Tufan A1 - Piotrowiak, T. A1 - Reinholz, Uwe A1 - Ludwig, A. A1 - Emmerling, Franziska A1 - Streli, C. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin T1 - Exploring the Depths of Corrosion: A Novel GE-XANES Technique for Investigating Compositionally Complex Alloys N2 - In this study, we propose the use of nondestructive, depth-resolved, element-specific characterization using grazing exit X-ray absorption near-edge structure spectroscopy (GE-XANES) to investigate the corrosion process in compositionally complex alloys (CCAs). By combining grazing exit X-ray fluorescence spectroscopy (GE-XRF) geometry and a pnCCD detector, we provide a scanning-free, nondestructive, depth-resolved analysis in a sub-micrometer depth range, which is especially relevant for layered materials, such as corroded CCAs. Our setup allows for spatial and energy-resolved measurements and directly extracts the desired fluorescence line, free from scattering events and other overlapping lines. We demonstrate the potential of our approach on a compositionally complex CrCoNi alloy and a layered reference sample with known composition and specific layer thickness. Our findings indicate that this new GE-XANES approach has exciting opportunities for studying surface catalysis and corrosion processes in real-world materials. KW - Degradation mechanisms KW - Grazin exit XANES KW - Depth resolved XANES KW - Compositional complex alloys KW - Corrosion PY - 2023 U6 - https://doi.org/10.1021/acs.analchem.3c00404 VL - 95 SP - 4810 EP - 4818 PB - ACS Publications AN - OPUS4-57823 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Yusenko, Kirill A1 - Stawski, Tomasz A1 - Kulow, Anicó A1 - Cakir, Cafer Tufan A1 - Röder, Bettina A1 - Naese, Christoph A1 - Britzke, Ralf A1 - Sintschuk, Michael A1 - Emmerling, Franziska T1 - BAMline - A real-life sample materials research beamline N2 - With increasing demand and environmental concerns, researchers are exploring new materials that can perform as well or better than traditional materials while reducing environmental impact. The BAMline, a real-life sample materials research beamline, provides unique insights into materials’ electronic and chemical structure at different time and length scales. The beamline specializes in x-ray absorption spectroscopy, x-ray fluorescence spectroscopy, and tomography experiments. This enables real-time optimization of material properties and performance for various applications, such as energy transfer, energy storage, catalysis, and corrosion resistance. This paper gives an overview of the analytical methods and sample environments of the BAMline, which cover non-destructive testing experiments in materials science, chemistry, biology, medicine, and cultural heritage. We also present our own synthesis methods, processes, and equipment developed specifically for the BAMline, and we give examples of synthesized materials and their potential applications. Finally, this article discusses the future perspectives of the BAMline and its potential for further advances in sustainable materials research. KW - Extended X-ray absorption fine structure KW - Energy storage KW - Environmental impacts KW - Nondestructive testing techniques KW - X-ray fluorescence spectroscopy KW - Corrosion KW - Near edge X-ray absorption fine structure spectroscopy KW - X-ray absorption spectroscopy PY - 2023 U6 - https://doi.org/10.1063/5.0157194 VL - 158 IS - 24 SP - 1 EP - 22 PB - AIP Publishing AN - OPUS4-57824 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-578254 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 - Karafiludis, Stephanos A1 - de Oliveira Guilherme Buzanich, Ana A1 - Heinekamp, Christian A1 - Smales, Glen Jacob A1 - Hodoroaba, Vasile-Dan A1 - ten Elshof, J. E. A1 - Emmerling, Franziska A1 - Stawski, Tomasz T1 - Template-free synthesis of mesoporous, amorphous transition metal phosphate materials N2 - We present how mesoporosity can be engineered in transition metal phosphate (TMPs) materials in a template-free manner. The method involves a transformation of a precursor metal phosphate phase, called M-struvite (NH4MPO4·6H2O, M = Mg2+, Ni2+, Co2+, NixCo1-x2+). It relies on the thermal decomposition of crystalline M-struvite precursors to an amorphous and simultaneously mesoporous phase, which forms while degassing of NH3 and H2O. The temporal evolution of mesoporous frameworks and the response of the metal coordination environment were followed with in-situ and ex-situ scattering and diffraction, as well as X -ray spectroscopy. Despite sharing the same precursor struvite structure, different amorphous and mesoporous structures were obtained depending on the involved transition metal. We highlight the systematic differences in absolute surface area, pore shape, pore size, and phase transitions depending on a metal cation present in the analogous M-struvites. The amorphous structures of thermally decomposed Mg-, Ni- and NixCo1-x-struvites exhibit high surface areas and pore volumes (240 m²g-1 and 0.32 cm-3 g-1 for Mg and 90 m²g-1 and 0.13 cm-3 g-1 for Ni). We propose that the low-cost, environmentally friendly M-struvites could be obtained as recycling products from industrial and agricultural wastewaters. These waste products could be then upcycled into mesoporous TMPs through a simple thermal treatment for further applications, for instance, in (electro)catalysis. KW - Struvite KW - Pphosphates KW - Transition metal KW - In-situ SAXS/WAXS KW - Mesoporosity PY - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-569503 SN - 2040-3364 SP - 1 EP - 15 PB - Royal Society of Chemistry (RSC) AN - OPUS4-56950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karafiludis, Stephanos A1 - Ryll, T. W. A1 - Buzanich, Ana Guilherme 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-579151 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 - Somasundaram, S. K. A1 - Buzanich, Ana A1 - Emmerling, Franziska A1 - Krishnan, S. A1 - Senthilkumar, K. A1 - Joseyphus, R.J. T1 - New insights into pertinent Fe-complexes for the synthesis of iron via the instant polyol process N2 - Chemically synthesized iron is in demand for biomedical applications due to its large saturation magnetization compared to iron oxides. The polyol process, suitable for obtaining Co and Ni particles and their alloys, is laborious in synthesizing Fe. The reaction yields iron oxides, and the reaction pathway remains unexplored. This study shows that a vicinal polyol, such as 1,2-propanediol, is suitable for obtaining Fe rather than 1,3-propanediol owing to the formation of a reducible Fe intermediate complex. X-ray absorption spectroscopy analysis reveals the ferric octahedral geometry and tetrahedral geometry in the ferrous state of the reaction intermediates in 1,2-propanediol and 1,3-propanediol, respectively. The final product obtained using a vicinal polyol is Fe with a γ-Fe2O3 shell, while the terminal polyol is favourable for Fe3O4. The distinct Fe–Fe and Fe–O bond lengths suggest the presence of a carboxylate group and a terminal alkoxide ligand in the intermediate of 1,2-propanediol. A large Fe–Fe bond distance suggests diiron complexes with bidentate carboxylate bridges. Prominent high-spin and low-spin states indicate the possibility of transition, which favors the reduction of iron ions in the reaction using 1,2-propanediol. KW - XAS KW - Nanoparticle PY - 2023 U6 - https://doi.org/10.1039/D3CP01969A SN - 1463-9076 VL - 25 IS - 33 SP - 21970 EP - 21980 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58073 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karafiludis, Stephanos A1 - Bhattacharya, Biswajit A1 - de Oliveira Guilherme Buzanich, Ana A1 - Fink, Friedrich A1 - Feldmann, Ines A1 - ten Elshof, J. E. A1 - Emmerling, Franziska A1 - Stawski, Tomasz T1 - Thermally processed Ni-and Co-struvites as functional materials for proton conductivity N2 - We present how mesoporosity can be engineered in transition metal phosphate (TMPs) materials in a template-free manner. The method involves the transformation of a precursor metal phosphate phase, called M-struvite (NH4MPO4·6H2O, M = Mg2+, Ni2+, Co2+, NixCo1−x2+). It relies on the thermal decomposition of crystalline M-struvite precursors to an amorphous and simultaneously mesoporous phase, which forms during degassing of NH3 and H2O. The temporal evolution of mesoporous frameworks and the response of the metal coordination environment were followed by in situ and ex situ scattering and diffraction, as well as X-ray spectroscopy. Despite sharing the same precursor struvite structure, different amorphous and mesoporous structures were obtained depending on the involved transition metal. We highlight the systematic differences in absolute surface area, pore shape, pore size, and phase transitions depending on the metal cation present in the analogous M-struvites. The amorphous structures of thermally decomposed Mg-, Ni- and NixCo1−x-struvites exhibit high surface areas and pore volumes (240 m2 g−1 and 0.32 cm−3 g−1 for Mg and 90 m2 g−1 and 0.13 cm−3 g−1 for Ni). We propose that the low-cost, environmentally friendly M-struvites could be obtained as recycling products from industrial and agricultural wastewaters. These waste products could be then upcycled into mesoporous TMPs through a simple thermal treatment for further application, for instance in (electro)catalysis. KW - Struvite KW - Phosphates KW - Transition metals KW - Proton conductivity PY - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-575862 SN - 1477-9226 SP - 1 EP - 13 PB - Royal Society of Chemisty (RSC) CY - London/Cambridge AN - OPUS4-57586 LA - deu 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 - 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-584924 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 - Peters, Stefan A1 - Bartling, Stephan A1 - Parlinska-Wojtan, Magdalena A1 - Wotzka, Alexander A1 - Guilherme Buzanich, Ana A1 - Wohlrab, Sebastian A1 - Abdel-Mageed, Ali M. T1 - Stabilization of intermediate Mo oxidation states by Nb doping enhancing methane aromatization on Mo/HZSM-5 catalysts N2 - The dehydroaromatization of methane is a promising process to produce aromatics and ultra-pure hydrogen. Increased yields and stability of Mo/HZSM-5 against irreversible deactivation were achieved via a redox interaction by doping with otherwise inert Nb. KW - General Materials Science KW - Sustainability and the Environment KW - General Chemistry KW - Renewable Energy PY - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-597670 SN - 2050-7488 SP - 1 EP - 16 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59767 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dietzmann, Simon A1 - Mehmood, Asad A1 - Guilherme Buzanich, Ana A1 - Emmerling, Franziska A1 - Fellinger, Tim-Patrick A1 - Thomas, A. T1 - Characterization of Solid-State Complexes by XAS N2 - Atomically dispersed metal-nitrogen doped carbons (M-N-C) are promising catalysts for the activation of small molecules such as O2 and CO2. These single atom catalysts (SAC) operate at the interface between homogenous and heterogenous catalysts. Currently, many examples of M-N-C are known with good oxygen reduction reaction activity but lacking a controlled synthesis of the specific active sites of the precatalyst. Recently, our group facilitated the synthesis of pure pyrrolic M-N4 sites using Zn ions as imprinters.[1] These amorphous materials obtained by active site imprinting method are characterized at the BAMline (Bessy II) by X-ray absorption spectroscopy (XAS). In-situ/operando measurements will be crucial in future work for a better understanding of the dynamic changes of the active site. T2 - InSynX Workshop 2023 CY - Sao Paulo, Brazil DA - 06.03.2023 KW - Solid-State Complexes PY - 2023 AN - OPUS4-58933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinekamp, Christian A1 - Kneiske, Sönke A1 - 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-593433 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 - JOUR A1 - Edzards, Joshua A1 - Saßnick, Holger-Dietrich A1 - Buzanich, Ana Guilherme A1 - Valencia, Ana M. A1 - Emmerling, Franziska A1 - Beyer, Sebastian A1 - Cocchi, Caterina T1 - Effects of Ligand Substituents on the Character of Zn-Coordination in Zeolitic Imidazolate Frameworks N2 - Due to their favorable properties and high porosity, zeolitic imidazolate frameworks (ZIFs) have recently received much limelight for key technologies such as energy storage, optoelectronics, sensorics, and catalysis. Despite widespread interest in these materials, fundamental questions regarding the zinc coordination environment remain poorly understood. By focusing on zinc(II)2-methylimidazolate (ZIF-8) and its tetrahedrally coordinated analogues with Br-, Cl-, and H-substitution in the 2-ring position, we aim to clarify how variations in the local environment of Zn impact the charge distribution and the electronic properties of these materials. Our results from densityfunctional theory confirm the presence of a Zn coordinative bond with a large polarization that is quantitatively affected by different substituents on the organic ligand. Moreover, our findings suggest that the variations in the Zn coordination induced by the functionalization have a negligible effect on the electronic structure of the considered compounds. On the other hand, halogen terminations of the ligands lead to distinct electronic contributions in the vicinity of the frontier region which ultimately reduce the band gap size by a few hundred millielectron volts. Experimental results obtained from X-ray absorption spectroscopy (Zn K-edge) confirm the trends predicted by theory and, together with them, contribute to a better understanding of the structure−property relationships that are needed to tailor ZIFs for target applications. KW - Surfaces KW - Physical and Theoretical Chemistry KW - General Energy KW - Electronic KW - Coatings and Films KW - Optical and Magnetic Materials PY - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-589117 SN - 1932-7447 VL - 127 IS - 43 SP - 21456 EP - 21464 PB - American Chemical Society (ACS) AN - OPUS4-58911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinekamp, Christian A1 - 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-582249 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 - Weber, Kathrin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Stephan-Scherb, Christiane T1 - A µ‐XANES study of the combined oxidation/sulfidation of Fe–Cr model alloys N2 - The precise analysis of cation diffusion profiles through corrosion scales is an important aspect to evaluate corrosion phenomena under multicomponent chemical load, as during high‐temperature corrosion under deposits and salts. The present study shows a comprehensive analysis of cation diffusion profiles by electron microprobe analysis and microbeam X‐ray absorption near edge structure (µ‐XANES) spectroscopy in mixed oxide/sulfide scales grown on Fe–Cr model alloys after exposing them to 0.5% SO2. The results presented here correspond to depth‐dependent phase identification of oxides and sulfides in the corrosion scales by µ‐XANES and the description of oxidation‐state‐dependent diffusion profiles. Scales grown on low‐ and high‐alloyed materials show both a well‐pronounced diffusion profile with a high concentration of Fe3+ at the gas and a high concentration of Fe2+ at the alloy interface. The distribution of the cations within a close‐packed oxide lattice is strongly influencing the lattice diffusion phenomena due to their different oxidation states and therefore different crystal‐field preference energies. This issue is discussed based on the results obtained by µ‐XANES analysis. KW - X-ray absorption spectroscopy KW - Oxidation KW - Sulfidation PY - 2019 U6 - https://doi.org/10.1002/maco.201810644 VL - 70 IS - 8 SP - 1360 EP - 1370 PB - Wiley VCH-Verlag AN - OPUS4-47934 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -