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Extending the depth range in energy dispersive X ray stress analysis by simultaneous multi detector data acquisition in equatorial scattering geometry
Full text linkA scattering geometry for depth resolved energy dispersive X ray stress analysis on polycrystalline materials is introduced. Via simultaneous data acquisition during a sin2 amp; 968; measurement using two detectors arranged in the horizontal diffraction plane, it aims to extend the accessible information depth to the free surface as well as deeper material zones. While data acquisition with the first detector takes place in a symmetrical configuration with regard to the incident and exit angles, amp; 945;i and amp; 945;e, respectively, the second detector runs in an asymmetrical mode, defined by amp; 945;i amp; 8197; lt; amp; 8197; amp; 945;e. Therefore, the scattering vectors assigned to the two diffraction geometries run in different tilt planes during a amp; 967; scan of the sample performed in the Eulerian cradle. Treatment of the data recorded in the asymmetric diffraction mode requires modifications of the fundamental equation of X ray stress analysis, which are discussed using the example of measurements performed on a unidirectionally ground ferritic steel sampl
Preparing the next phase of the steady state microbunching proof of principle experiment at the Metrology Light Source
Full text linkSteady state microbunching SSMB is a proposed scheme to generate coherent radiation at short wavelengths from a microbunched electron beam in a storage ring. The feasibility of the idea is investigated in an ongoing proofof principle PoP experiment conducted at the Metrology Light Source MLS . Phase I of the SSMB PoP experiment has been using an experimental setup employing a singleshot modulation laser to show the general viability of the idea, and has explored the underlying complex storage ring dynamics. The next step in the SSMB PoP campaign is to progress from the single shot setup of phase I towards quasi steady state. To this end, a new laser system is installed at the MLS that can provide turn by turn modulation of the electron beam for 1000 revolutions or more. The main goal of this phase II of the SSMB PoP experiment will be to show bounded motion of electrons within individual laser induced microbunches. In this paper, we show the progress of preparation for PoP phase II, with emphasis on the setup and integration of the new laser system and diagnostics challenge
Elucidating the Structure and the Impact of Synthesis Methods on the Flexibility of the Metal Organic Framework MIL 88 A Fe During Water Capture
No full textFlexible metal organic frameworks MOFs have emerged as a new generation of porous materials and are considered for various applications such as sensing, water or gas capture, and water purification. MIL amp; 8722;88 A Fe is one of the earliest and most researched flexible MOFs, but to date, there is a lack in the structural aspects that govern its dynamic behaviour. Here, we report the first crystal structure of DMF solvated MIL amp; 8722;88 A and investigate the impact of real structure effects on the dynamic behaviour of MIL amp; 8722;88 A Fe , particularly upon water adsorption. Four differently synthesized materials are studied with powder X ray diffraction PXRD , THz Raman spectroscopy, and N2 sorption. The very high water vapor sorption capacity is probed by utilizing in situ humidity PXRD and calorimetric cycling studies. At least four different crystallographic phases are identified during the sorption measurements and a structural concept and models are developed that explain the changes in the XRD patterns. From this, it is derived that MIL amp; 8722;88 A Fe is an excellent material for a new concept of responsive water harvesting technologie
High Valent Intermediate Observed in a Cu Based OER Electrocatalyst by Operando X ray Absorption Spectroscopy
Full text linkUnderstanding the chemical transformations governing the oxygen evolution reaction OER in Cu based electrocatalysts is critical for advancing cost efficient alkaline water splitting technologies. In this study, we employ synchrotron based operando Cu L3 edge X ray absorption spectroscopy XAS and potentiodynamic techniques to probe the key intermediate species involved in alkaline OER. Our findings reveal that this metastable species exhibits an electronic structure resembling high valent Cu complexes, particularly those associated with the CuO2 ion. Potentiodynamic measurements indicate that the high valent intermediate emerges at potentials as low as 1.62 VRHE, coinciding with the oxidative process traditionally attributed to the Cu2 amp; 8596; Cu3 redox transition, suggesting that the formation of the high valent intermediate is directly linked to this redox process. This work provides valuable insights into the interplay between redox chemistry and catalytic performance in Cu based OER electrocatalysts and provides further insights into the nature of the chemical species governing the oxygen evolution reaction mechanis
Pyramidal Nd2ScN inside an icosahedral C80 cage
No full textEngineering the structure of the M3N cluster within a fullerene cage by the combination of versatile metal ions is one of the most powerful strategies to build metallofullerenes with fine tuned structures and properties. However, alongside their compositional versatility, mixed metal clusters pose a challenge for structural elucidation because of the overlapping positions of different metal atoms. Here, we expand the size of metal ions in M2ScN C80 to M Nd3 R3 0.983 , whose large ionic radius results in the pyramidalization of encapsulated Nd2ScN, which is the first example of a pyramidal M2ScN cluster inside C80. The combination of the pyramidalization, strong alteration of Nd N and Sc N bond lengths, and an overlap of two cluster orientations results in four nitrogen sites, which were unambiguously located by single crystal X ray diffraction SC XRD . We demonstrate that judicious modelling of non metal and overlapping metal positions is paramount for precise SC XRD determination of structural parameters in metallofullerenes, which will otherwise suffer from erroneous structural interpretations. These results deepen our understanding of the fascinating M3N C80 and pave the way for better control over the fine tuning of their structures and propertie
Impact of Secondary Phases on the Electrochemical Performance of Li6.4La3Zr1.4Ta0.6O12 Garnet Solid Electrolytes through Grain Boundary Engineering
No full textFast conducting Li7La3Zr2O12 LLZO type garnet solid state electrolytes face the considerable challenge of deleterious metallic dendrite formation during operation, with suggestions that this behavior may be linked to electronic conductivity effects. To examine in detail how electronic conductivity effects at the grain boundary can affect the electronic properties of cubic LLZO type garnets, we report a family of Ta doped LLZO garnets with a Mn containing secondary phase, which is spatially selective toward the grain boundaries. The inclusion of this targeted grain boundary phase, whose composition is revealed as La4LiMnO8, alters the ionic and local electronic conductivities of the final composite, resulting in improvements in the observed critical current densities. We find that the critical current density before short circuiting is highly dependent on this secondary phase, increasing with increasing content up to a maximum of 0.30 mA cm 2. X ray absorption spectroscopy and X ray diffraction computed tomography studies complement these findings, revealing that a darkening of the composite electrolyte post cycling is accompanied by Mn reduction and a reduction in the phase fraction of La4LiMnO8. Guided by electrochemical characterization and finite element analysis, we highlight the critical role of grain boundaries in bulk garnet degradation pathways and evidence how spatially targeted secondary phases, introduced during initial synthesis, can impact electrochemical performance in LLZO type garnet
BIPV vereint Ästhetik und Stromerzeugung
No full textBalkon Kraftwerke boomen. Aber auch mit Fassaden lässt sich Sonnenstrom ernten. Das Konzept der gebäudeintegrierten Photovoltaik BIPV ist vor allem im Winter interessan
Deformation mechanisms of nanoporous flexible transparent electrodes based on particle free silver inks
Full text linkIn this work, we explore the relationships between the morphology, deformation behavior, and functionality of transparent electrodes based on metal organic decomposition MOD silver inks on PET substrates. A self organized nanoporous microstructure with good interconnectivity of silver ligaments is shown to provide the necessary optical transparency and sufficient conductivity of the electrode. Tensile tests with in situ resistance measurements revealed moderate resistance increase with increasing applied strain, indicating the suitability of the coatings for flexible electronics applications. With the help of in situ scanning electron microscopy in combination with digital image correlation, it is demonstrated that cracks which are generated during a tensile test are short and isolated, which is beneficial for good electromechanical stability during monotonic and cyclic loading. In contrast to alternative methods for synthesis of nanoporous ultrathin films, the demonstrated transparent electrode is fabricated by a single printing curing process under very low consumption of particle free MOD ink, thus being suitable for cost effective mass productio
Understanding the Interplay Between Pore Structure and Ionic Liquid Interaction on the Gas Uptake of Microporous Carbons
Full text linkInterfaces formed between porous carbon materials and ionic liquids ILs play an essential role in catalysis as well as in electrochemical energy storage and energy conversion. Profound knowledge about the formed local structures on a molecular level is essential to create the desired physicochemical environments and to control the remaining porosity of the involved carbon materials. In the present study, the interplay between pore structure and ionic liquid IL loading in CO2 activated microporous carbons is investigated with a special focus on the gas adsorption properties of the remaining hybrid materials. Two activated carbon materials with distinct micropore sizes AC30 and AC120 are loaded with two hydrophobic ILs, namely 1 ethyl 3 methylimidazolium bis trifluormethylsulfonyl imid EMIM TFSI and tributyloctyl phosphonium tris pentafluoroethyl trifluorophosphate P4448 eFAP , at varying contents. The results reveal that IL configuration within the pores is crucial for gas uptake EMIM TFSI maintains open porosity in larger micropores AC120 but completely fills the smaller ones AC30 , whereas P4448 eFAP forms closed porosity by covering pore openings, enhancing gas uptake in residual pores e.g., for CO2 at 273 K . N2 sorption at 298 K highlights the pronounced confinement effect of EMIM TFSI in smaller pores, leading to significant gas uptake. X ray diffraction XRD , small angle X ray scattering SAXS , and differential scanning calorimetry DSC analyses confirm these configurations and show that high IL loading induces bulk like behavior. These findings demonstrate how ionic liquids can be used to steplessly modify pore structures and influence solid liquid gas interfaces, providing insights into tailoring properties such as gas uptakes, hydrophobicity, and other physicochemical characteristics by their interaction with porous carbon material
Selective Light Driven CO2 to CO Reduction by a [FeFe] Hydrogenase Mimic in Water
Full text linkWe report a biomimetic system for light driven CO2 conversion in lipid bilayers using a [FeFe] hydrogenase inspired molecular dyad PS CAT acting simultaneously as photosensitizer and catalyst. The molecular design of PS CAT consists of both light harvesting and catalytically active moieties in a single molecule. This structure allows for efficient charge transfer between these two moieties. The PS CAT consists of only an organic chromophore and an iron complex. Photocatalytic reduction of CO2 to CO CO2RR as well as H 2 production HER was traced over 56 h to determine CO2RR HER selectivity. The presence of water in the lipid bilayer system allows for CO2RR selectivity gt;99 over the competitive HER, outperforming previous molecular, and liposome based systems for light driven CO2 to CO conversion. The product selectivity in CO2RR e.g., CO, HCOO , and CH4 was determined via gas chromatography and NMR spectroscopy with C 13 labeled carbon sources. The Stern Volmer quenching studies on the initial light driven electron transfer revealed static quenching and indicated a preassembly of the PS CAT with the electron donor at the membrane water interfac