TY - JOUR
A1 - Terborg, R.
A1 - Procop, Mathias
T1 - Theoretical calculation and experimental determination of x-ray production efficiencies for copper, zirconium, and tungsten
N2 - The X-ray intensities of the K-, L- and M-lines of copper, zirconium and tungsten have been measured with an energy-dispersive X-ray spectrometer of known efficiency as function of photon energy. X-ray production efficiencies were determined from the measured intensities for Kα- and L-series of Cu and Zr and for the L- and M-series of W. These data were compared to calculated X-ray production efficiencies based on the widely used matrix correction models of Pouchou and Pichoir (XPP) and Bastin (PROZA96).
Our results indicate that a replacement of the stopping power in the PROZA96 algorithm by expressions of Joy and Jablonski has only a minor influence on the calculated X-ray production efficiencies. In contrast, the modifications of the ionization cross-section show a stronger effect. We replaced the ionization cross-sections for K lines of the PROZA96 algorithm with different models.
The results for L- and M-Lines are different. For the L-lines of Cu the original XPP and PROZA96 models show the best agreement while using the Bote cross-sections result in an overestimation. For the Zr-L and W-L1, -L2, -L3 X-ray production efficiencies, the Bote cross-sections lead to a significant improvement compared to all other models. The original XPP model represents the best agreement for the M5 efficiencies but underestimates the M4 efficiencies.
There is no superior model or modification because the parameter sets in the models need to be aligned to each other. However, using the ionization cross-sections of Bote, which are based on quantum mechanical calculations, show promising results in many cases.
KW - X-ray production efficiency
KW - EPMA
KW - Copper
KW - Zirconium
KW - Tungsten
PY - 2023
DO - https://doi.org/10.1093/micmic/ozad067.110
SN - 1435-8115
VL - 29
IS - Supplement 1
SP - 245
EP - 246
PB - Oxford University Press
CY - Oxford
AN - OPUS4-58339
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weidner, Steffen
A1 - Meyer, A.
A1 - Kricheldorf, H. R.
T1 - Alcohol-initiated and Tin(II) 2-ethylhexanoate-catalyzed polymerization of L-lactide in bulk – About separate crystallization of cyclic and linear Poly (L-lactide)s
N2 - Alcohol-initiated ROPs of L-Lactide were performed at 140 ◦C in bulk with variation of the initiator/catalyst ratio and time. Lower ratios favor the formation of cycles which upon annealing display a change of the MALDI mass peak distribution towards a new maximum with a “saw-tooth pattern” of the mass peaks representing the cycles.
Such a pattern was not observed for the mass peak of the linear chains. The coexistence of these patterns indicate that linear and cyclic poly (L-lactide)s (PLA) crystallize in separate crystals, and that the crystallites of the cycles are made up by extended rings. High Tm and ΔHm values confirm that these extended-ring crystallites represent a thermodynamically optimized form of PLA. Experiments with preformed cyclic and linear PLAs support this interpretation.
KW - Polylactide
KW - MALDI-TOF MS
KW - Crystalinity
KW - Polymerization
PY - 2023
DO - https://doi.org/10.1016/j.polymer.2023.126355
VL - 285
IS - 126355
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-58355
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Fareed, Adnan
A1 - Rosalie, Julian M.
A1 - Kumar, Sourabh
A1 - Kar, S.
A1 - Hickel, Tilmann
A1 - Fähler, S.
A1 - Maaß, Robert
T1 - Constrained incipient phase transformation in Ni-Mn-Ga films: A small-scale design challenge
N2 - Ni-Mn-Ga shape-memory alloys are promising candidates for large strain actuation and magnetocaloric cooling devices. In view of potential small-scale applications, we probe here nanomechanically the stress-induced austenite–martensite transition in single crystalline austenitic thin films as a function of temperature. In 0.5 μm thin films, a marked incipient phase transformation to martensite is observed during nanoindentation, leaving behind pockets of residual martensite after unloading. These nanomechanical instabilities occur irrespective of deformation rate and temperature, are Weibull distributed, and reveal large spatial variations in transformation stress. In contrast, at a larger film thickness of 2 μm fully reversible transformations occur, and mechanical loading remains entirely smooth. Ab-initio simulations demonstrate how an in-plane constraint can considerably increase the martensitic transformation stress, explaining the thickness-dependent nanomechanical behavior. These findings for a shape-memory Heusler alloy give insights into how reduced dimensions and constraints can lead to unexpectedly large transformation stresses that need to be considered in small-scale actuation design.
KW - Shape-memory alloys
KW - Nanoindentation
KW - Incipient plasticity
KW - NiMaGa
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581422
DO - https://doi.org/10.1016/j.matdes.2023.112259
VL - 233
SP - 1
EP - 8
PB - Elsevier B.V.
AN - OPUS4-58142
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, Hans R.
A1 - Weidner, Steffen
T1 - Ring-ring equilibration (RRE) of cyclic poly(L-lactide)s by means of cyclic tin catalysts
N2 - With 2,2-dibutyl-2-stanna-1,3-dithiolane (DSTL) and 2-stanna-1,3-dioxa-4,5,6,7-dibenzoxepane (SnBiPh) as catalysts ring-expansion polymerizations (REP) were performed either in 2 M solution using three different solvents and two different temperatures or in bulk at 140 and 120 ◦C. A kinetically controlled rapid REP up to weight average molecular masses (Mẃs) above 300 000 was followed by a slower degradation of the molecular masses at 140 ◦C, but not at 120 ◦C Furthermore, a low molecular mass cyclic poly(L-lactide) (cPLA) with a Mn around 16 000 was prepared by polymerization in dilute solution and used as starting material for ring-ring equilibration at 140 ◦C in 2 M solutions. Again, a decrease of the molecular mass was detectable, suggesting that the equilibrium Mn is below 5 000. The degradation of the molecular masses via RRE was surprisingly more effective in solid cyclic PLA than in solution, and a specific transesterification mechanism involving loops on the surface of crystallites is proposed. This degradation favored the formation of extended-ring crystallites, which were detectable by a “saw-tooth pattern” in their MALDI mass spectra.
KW - Organic Chemistry
KW - Polymers and Plastics
KW - MALDI-TOF MS
KW - Materials Chemistry
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593819
DO - https://doi.org/10.1016/j.eurpolymj.2024.112765
SN - 0014-3057
VL - 206
SP - 1
EP - 8
PB - Elsevier B.V.
AN - OPUS4-59381
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Emamverdi, Farnaz
A1 - Huang, J.
A1 - Mosane Razavi, Negar
A1 - Bojdys, M. J.
A1 - Forster, A. B.
A1 - Budd, P. M.
A1 - Böhning, Martin
A1 - Schönhals, Andreas
T1 - Molecular Mobility and Gas Transport Properties of Mixed Matrix Membranes Based on PIM‑1 and a Phosphinine Containing Covalent Organic Framework
N2 - Polymers with intrinsic microporosity (PIMs) are gaining attention as gas separation membranes. Nevertheless, they face limitations due to pronounced physical aging. In this study a covalent organic framework containing λ5-phosphinine moieties, CPSF-EtO were incorporated as a nanofiller (concentration range 0-10 wt%) into a PIM-1 matrix forming dense films with a thickness of ca. 100 μm. The aim of the investigation was to investigate possible enhancements of gas transport properties and mitigating effects on physical aging. The incorporation of the nanofiller occurred on aggregate level with domains up to 100 nm as observed by T-SEM and confirmed by X-ray scattering. Moreover, the X-ray data show that the structure of the microporous network of the PIM-1 matrix is changed by the nanofiller.
As the molecular mobility is fundamental for gas transport as well as for physical aging, the study includes dielectric investigations of pure PIM-1 and PIM-1/CPSF-EtO mixed matrix membranes to establish a correlation between the molecular mobility and the gas transport properties. Using the time-lag method the gas permeability and the permselectivity were determined for N2, O2, CH4 and CO2 for samples with variation in filler content. A significant increase in the permeability of CH4 and CO2 (50 % increase compared to pure PIM-1) was observed for a concentration of 5 wt% of the nanofiller. Furthermore, the most pronounced change in the permselectivity was found for the gas pair CO2/N2 at a filler concentration of 7 wt%.
KW - Polymers of Intrinsic Microporosity
KW - Nanocomposites
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595031
DO - https://doi.org/10.1021/acs.macromol.3c02419
SN - 0024-9297
VL - 57
IS - 4
SP - 1829
EP - 1845
PB - ACS Publications
AN - OPUS4-59503
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - RPRT
A1 - Bartczack, Dorota
A1 - Taché, Olivier
A1 - Hodoroaba, Vasile-Dan
T1 - Report on the homogeneity assessment of bimodal gold materials (nPSize1 and nPSize2) and particle number concentration by frequency method
N2 - The main objective was to assess homogeneity of two bimodal gold materials, namely nPsize1 and nPSize2, containing approximately 1:1 and 10:1 particle number-based ratio of ~30nm and ~60nm particles. Particle number-based concentration within the two size fractions was determined with spICP-MS using the particle frequency method of calibration.
KW - Nanoparticles
KW - Homogeneity
KW - Particle number concentration
KW - Gold
KW - nPSize
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595451
DO - https://doi.org/10.5281/zenodo.10654245
SP - 1
EP - 5
PB - Zenodo
CY - Geneva
AN - OPUS4-59545
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Manoharan, Deepak
A1 - Ranjan, Subham
A1 - Emmerling, Franziska
A1 - Bhattacharya, Biswajit
A1 - Takamizawa, Satoshi
A1 - Ghosh, Soumyajit
T1 - Elasto-plastic behaviour with reversible thermosalient expansion in acrylonitrile-based organic crystals
N2 - Crystalline materials that exhibit reversible mechanical responses upon exposure to external stimuli have garnered significant attention owing to their potential applications in various fields. Herein, we report a crystal of (2Z,2′Z)-2,2′-(1,4-phenylene)bis(3-(4-bromophenyl)acrylonitrile) (DSBr), which displays simultaneous elasto-plastic behaviour and reversible thermosalient effects. While elasto-plastic behaviour is attributed to underlying packing features, reversible thermosalient expansion is attributed to uniaxial expansion mediated by heat. Exceptional length increase and contraction upon cooling is due to the restorative nature of weak interactions through a cooperative effect. The cooperative movement of molecules is reflected in the unidirectional expansion of the habit plane. Thermosalient reversible expansion–contraction in elasto-plastic crystals have not been discussed in the literature so far. Detailed analysis reported herein provides a comprehensive understanding of the underlying mechanism of flexibility and thermosalient responses. This crystal's unique blend of reversible thermal expansion with flexibility holds substantial promise for applications in flexible thermal actuators.
KW - Materials Chemistry
KW - General Chemistry
PY - 2024
DO - https://doi.org/10.1039/D3TC04272C
SN - 2050-7526
SP - 1
EP - 11
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-59527
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zhang, Kun
A1 - Carrod, Andrew J.
A1 - Del Giorgio, Elena
A1 - Hughes, Joseph
A1 - Rurack, Knut
A1 - Bennet, Francesca
A1 - Hodoroaba, Vasile-Dan
A1 - Harrad, Stuart
A1 - Pikramenou, Zoe
T1 - Luminescence Lifetime-Based Sensing Platform Based on Cyclometalated Iridium(III) Complexes for the Detection of Perfluorooctanoic Acid in Aqueous Samples
N2 - Luminescence lifetimes are an attractive analytical method for detection due to its high sensitivity and stability. Iridium probes exhibit luminescence with long excited-state lifetimes, which are sensitive to the local environment. Perfluorooctanoic acid (PFOA) is listed as a chemical of high concern regarding its toxicity and is classified as a “forever chemical”. In addition to strict limits on the presence of PFOA in drinking water, environmental contamination from industrial effluent or chemical spills requires rapid, simple, accurate, and cost-effective analysis in order to aid containment. Herein, we report the fabrication and function of a novel and facile luminescence sensor for PFOA based on iridium modified on gold surfaces. These surfaces were modified with lipophilic iridium complexes bearing alkyl chains, namely, IrC6 and IrC12, and Zonyl-FSA surfactant. Upon addition of PFOA, the modified surfaces IrC6-FSA@Au and IrC12-FSA @Au show the largest change in the red luminescence signal with changes in the luminescence lifetime that allow monitoring of PFOA concentrations in aqueous solutions. The platform was tested for the measurement of PFOA in aqueous samples spiked with known concentrations of PFOA and demonstrated the capacity to determine PFOA at concentrations >100 μg/L (240 nM).
KW - Perfluorooctanoic Acid (PFOA)
KW - Cyclometalated iridium (III) complexes
KW - Luminescent lifetime
KW - Optically active surfaces
KW - ToF-SIMS
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594535
UR - https://pubs.acs.org/doi/10.1021/acs.analchem.3c04289
DO - https://doi.org/10.1021/acs.analchem.3c04289
VL - 96
IS - 4
SP - 1565
EP - 1575
PB - American Chemical Society (ACS)
AN - OPUS4-59453
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Karafiludis, Stephanos
A1 - Stawski, Tomasz
A1 - Emmerling, Franziska
A1 - Retzmann, Anika
A1 - Scoppola, E.
A1 - Kochovski, Z.
A1 - ten Elshof, J.E.
A1 - Hodoroaba, Vasile-Dan
T1 - Deciphering the non-classical Crystallization of transition metal phosphates (TMP)
N2 - A crucial aspect of ensuring sustainable raw material utilization to meet global demand lies in the efficient recovery and reuse of critical elements and compounds. Phosphate, PO43-, and many transition metals e.g. Ni and Co are listed as critical raw materials (CRMs) due to their indispensable role in numerous industrial processes. However, these elements can also exert harmful environmental impacts, with phosphorus being a major contributor to anthropogenic eutrophication and transition metal ions acting as toxic pollutants, particularly in ground- and wastewaters. Typically, separate pathways have been considered to extract hazardous substances such as transition metals or phosphate, independently from each other. Here, we report the crystallization pathways of transition metal phosphate (TMP) compounds, M-struvite and M-phosphate octahydrate with M = Ni2+, Co2+, NixCo1-x2+, NH4MPO4∙6H2O, M3(PO4)2∙8H2O from aqueous solutions. The co-precipitation of these particular TMP compounds from industrial and agricultural wastewaters has high potential as a P- and 3d metal recovery route.
For efficient extraction and transformation of the TMPs, a comprehensive understanding of their nucleation and crystallization pathways from aqueous solutions is required. While the crystallization mechanisms of magnesium or calcium phosphate-bearing phases have been researched for many decades (e.g. struvite, apatite), investigations into TMP materials are relatively scarce and often focus on the adsorption of transition metals on the surface instead of their actual incorporation in minerals. In our study, we investigated in detail the precipitation process of several Co and Ni phosphates using ex- and in-situ spectroscopic-, spectrometric- and diffraction-/scattering-based techniques. We show that the crystallization behavior of TMPs, indeed deviates from a classical crystallization paradigm and follows a non-classical multi-step pathway. Our work extends the understanding of TMP crystallization by elucidating the formation of amorphous precursors preceding the final crystalline phase This time-dependent transition of the transition metal precursor phases can be observed by electron-imaging/tomography depicting a progressively changing amorphous solids until their ultimate reconfiguration to a crystal (Figure 1). Here, the two-metallic NixCo1-x-mixtures deviated anomalously in their reaction kinetics, crystallization outcome and participation of both metals from their pure endmembers. By measuring the crystallization with in-situ X-ray scattering and pH using a flow-through setup geometry, a complex prolonged interplay among nucleating entities e.g. and amorphous or crystalline solids could be observed in the metal phosphate mixtures reaching equilibrium after almost two and a half hours (Figure 2). Our results provide a holistic perspective on the crystallization behavior of transition metal phosphate phases, shedding light on their unique nucleation and growth kinetics involving structural and chemical transformations of the intermediate phases.
T2 - Granada Münster Discussion Meeting 2023
CY - Münster, Germany
DA - 29.11.2023
KW - Non-classical crystallization theory
KW - Transition metals
KW - Phosphates
PY - 2023
AN - OPUS4-59007
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Driscoll, Laura L.
A1 - Driscoll, Elizabeth H.
A1 - Dong, Bo
A1 - Sayed, Farheen N.
A1 - Wilson, Jacob N.
A1 - O’Keefe, Christopher A.
A1 - Gardner, Dominic J.
A1 - Grey, Clare P.
A1 - Allan, Phoebe K.
A1 - Michalchuk, Adam A. L.
A1 - Slater, Peter R.
T1 - Under pressure: offering fundamental insight into structural changes on ball milling battery materials
N2 - Synthesis of Li ion battery materials via ball milling has been a huge area of growth, leading to new high-capacity electrode materials, such as a number of promising disordered rocksalt (DRS) phases. In prior work, it was generally assumed that the synthesis was facilitated simply by local heating effects during the milling process. In this work, we show that ball milling Li2MoO4 leads to a phase transformation to the high pressure spinel polymorph and we report electrochemical data for this phase. This observation of the formation of a high pressure polymorph shows that local heating effects alone cannot explain the phase transformation observed (phenakite to spinel) and so indicates the importance of other effects. In particular, we propose that when the milling balls collide with the material, the resulting shockwaves exert a localised pressure effect, in addition to local heating. To provide further support for this, we additionally report ball milling results for a number of case studies (Li2MnO3, Li2SnO3, Nb2O5) which reinforces the conclusion that local heating alone cannot explain the phase transformations observed. The work presented thus provides greater fundamental understanding of milling as a synthetic pathway and suggests potential strategies to prepare such samples without milling (e.g., doping to create internal chemical pressure). In addition, we suggest that further research is needed into the effect of the use of milling as a route to smaller particles, since we believe that such milling may also be affecting the surface structure of the particles through the influence of the shockwaves generated.
KW - Pollution
KW - Nuclear Energy and Engineering
KW - Sustainability and the Environment
KW - Environmental Chemistry
KW - Renewable Energy
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-590086
DO - https://doi.org/10.1039/d3ee00249g
VL - 16
IS - 11
SP - 5196
EP - 5209
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-59008
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Casali, Lucia
A1 - Emmerling, Franziska
T1 - Use of the solvent-free mechanochemical method for a sustainable preparation of pharmaceuticals
N2 - With the growing interest in environmental issues on the part of governments and institutions, pharmaceutical industries are asked to reduce their environmental footprint. Given the major impact related to the use of solvents, the development of methodologies less solvent demanding is nowadays even more urgent. In light of that, mechanochemistry would be a suitable solvent-free technology since it promotes the activation of the chemical reactions between (generally) solid materials via inputs of mechanical energy. Since such reactions may occur outside the kinetic and thermodynamic rules of conventional solution chemistry, the main limit of mechanochemistry is the poor mechanistic understanding of the solid-state transformations involved, which is still hindering a widespread use of the method, as well a scale-up to the industrial level. However, the development of methods for real-time monitoring of the mechanochemical reactions enables obtaining (in)accessible information on reaction intermediates, new products, or reaction time, thus getting closer to a better understanding of the mechanistic behaviour. With the rules of this chemistry becoming increasingly clear, the new reaction pathways of mechanochemistry wouldn’t represent a limit anymore, but an asset, that may lead to lot of opportunities for the pharmaceutical industry.
T2 - Post Doc Day Berlin
CY - Berlin, Germany
DA - 02.11.2023
KW - Mechanochemistry
KW - Sustainability
KW - Pharmaceuticals
PY - 2023
AN - OPUS4-59010
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Emmerling, Franziska
T1 - Understanding mechanochemical reactions: Real-time insights and collaborative research
N2 - Mechanochemistry emerges as a potent, environmentally friendly, and straightforward approach for crafting novel multicomponent crystal systems. Various milling parameters, including milling frequency, time, filling degree of the milling jar, ball diameter, vessel size, degree of milling ball filling, and material of jars, are recognized influencers on the mechanisms and rates of product formation. Despite the growing interest in mechanochemistry, there exists a gap in understanding the mechanistic aspects of mechanochemical reactivity and selectivity. To address this, diverse analytical methods and their combinations, such as powder X-ray diffraction, X-ray absorption spectroscopy, NMR, Raman spectroscopy, and thermography, have been developed for real-time, in situ monitoring of mechanochemical transformations.
This discussion centers on our recent findings, specifically investigating the formation of (polymorphic) cocrystals and metal-organic frameworks. Through these studies, we aim to unravel the impact of milling parameters and reaction sequences on the formation mechanism and kinetics. Notably, in the mechanochemical chlorination reaction of hydantoin, normalizing kinetic profiles to the volume of the milling ball unequivocally demonstrates the conservation of milling reaction kinetics. In this ball-milling transformation, physical kinetics outweigh chemical factors in determining reaction rates. Attempting to interpret such kinetics solely through chemical terms poses a risk of misinterpretation. Our results highlight that time-resolved in situ investigations of milling reactions provide a novel avenue for fine-tuning and optimizing mechanochemical processes.
T2 - PhD Seminar
CY - Online meeting
DA - 12.10.2023
KW - Mechanochemistry
KW - In situ
PY - 2023
AN - OPUS4-59022
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Goswami, Juli Nanda
A1 - Haque, Najirul
A1 - Seikh, Asiful H.
A1 - Bhattacharya, Biswajit
A1 - Emmerling, Franziska
A1 - Bar, Nimai
A1 - Ifseisi, Ahmad A.
A1 - Biswas, Surajit
A1 - Dolai, Malay
T1 - Carboxylative cyclization of propargyl alcohols with carbon dioxide for the synthesis of α-alkylidene cyclic carbonates in presence of Co(III) schiff base complex catalyst
N2 - A cobalt(III) complex, [Co(L)3](DMF) (1) of Schiff base ligand HL, 2-((E)-(benzylimino)methyl)-4-bromophenol is prepared and single crystal X-ray structural analysis have also been performed. The structures of complex 1 showed hexa-coordinated mononuclear systems that adopt octahedral geometry. The complex has also exhibited the supramolecular networks through non-covalent interactions like H-bonding, C–Hπ stacking. Moreover, the complex 1 is very effective in the catalytic fixation of carbon dioxide in propergyl alcohols to produce α-alkylidene cyclic carbonates. The catalytic production of α-alkylidene cyclic carbonates have been carried out through carboxylative cyclization of propargyl alcohols using CO2 balloon of 1 atm pressure at 80 ◦C. Solvent free condition (green synthesis) made this catalytic protocol eco-friendly towards the environment. Utilizing various substrates of propargyl alcohols moderate to high percentage yield (62–95%) of respective α-alkylidene cyclic carbonates product have been isolated over this catalytic reaction. Besides, the theoretical calculations (DFT) was performed for the prediction of probable mechanism of the catalytic reaction
KW - Catalytic fixation of carbon dioxide
KW - Carboxylative cyclization of propargyl alcohols
KW - Cobalt (III) Schiff base complex
KW - X-ray crystal analysis
PY - 2024
DO - https://doi.org/10.1016/j.molstruc.2023.136868
SN - 0022-2860
VL - 1296
IS - Part 1
SP - 1
EP - 8
PB - Elsevier B.V.
AN - OPUS4-58947
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Gugin, Nikita
A1 - Schwab, Alexander
A1 - Villajos Collado, José Antonio
A1 - Emmerling, Franziska
T1 - Reactive extrusion of a model BSA@ZIF-8 biocomposite: a scalable, continuous and sustainable approach
N2 - Metal-organic framework-based biocomposites (MOF-biocomposites) are promising materials for biosensing, biocatalysis, and delivery of biopharmaceuticals. One of the most studied MOFs for bioapplications is ZIF-8 (zeolitic imidazolate framework 8) due to its high surface area, high thermal and chemical stability, and low cytotoxicity. The conventional synthesis of ZIF-8-biocomposites called biomimetic mineralization includes mixing selected biomolecules 2-methylimidazole, and soluble Zn2+ source in water. Despite the high efficiency of the method, it does not allow for large-scale production and is restricted to hydrophilic biomolecules. Aimed at developing a scalable and versatile approach, we adapted our recently-reported ZIF-8 reactive extrusion for biocomposite production.
We selected bovine serum albumin (BSA) as an inexpensive model biomacromolecule for the preparation of biocomposites. The synthesis of BSA@ZIF-8 was performed using a twin-screw extruder ZE 12 HMI (Three-Tec Gmbh) at a mild temperature of 40 °C. Automatic volumetric feeder ZD 12B (Three-Tec GmbH) was used to supply the reagent mixture consisting of 2-methylimidazole, zinc source, and BSA. To initiate the reaction, a catalytic amount of EtOH was added using a peristaltic pump BT-L (Lead Fluid, China). Powder X-Ray diffraction (PXRD), thermogravimetric analysis (TGA), FTIR, and N2 adsorption were used to characterize the extrudates.
Highly crystalline and pure BSA@ZIF-8 with different BSA loadings was isolated after washing the extrudate with EtOH and sodium dodecyl sulfate. The EtOH feeding rate was optimized by following the protein encapsulation efficiency at a BSA mass fraction of 10%. A continuous extruder operation under optimized conditions showed good reproducibility and capability of producing biocomposites on the kilograms scale. These results provide highly valuable information for cheap and large-scale production of ZIF-8-based biocomposites. Due to the lack of restrictions on molecule size and solubility, our proof-of-concept study may significantly expand the selection of biomolecules for immobilization in ZIF-8, making the method applicable to various functional applications
T2 - Tag der Chemie 2023
CY - Berlin, Germany
DA - 05.07.2023
KW - Biocomposite
KW - MOFs
KW - Reactive extrusion
KW - Zeolitic imidazolate framework
PY - 2023
AN - OPUS4-58949
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Gugin, Nikita
A1 - Villajos Collado, José Antonio
A1 - Emmerling, Franziska
T1 - Chemists have solutions and know how to get rid of them
N2 - Metal-organic framework-based biocomposites (MOF-biocomposites) are promising materials for biosensing, biocatalysis, and delivery of biopharmaceuticals. One of the most studied MOFs for bioapplications is ZIF-8 (zeolitic imidazolate framework 8) due to its high surface area, high thermal and chemical stability, and low cytotoxicity. The conventional synthesis of ZIF-8-biocomposites called biomimetic mineralization includes mixing selected biomolecules 2-methylimidazole, and soluble Zn2+ source in water.[3] Despite the high efficiency of the method, it does not allow for large-scale production and is restricted to hydrophilic biomolecules. Aimed at developing a scalable and versatile approach, we adapted our recently-reported ZIF-8 reactive extrusion for biocomposite production.
We selected bovine serum albumin (BSA) as an inexpensive model biomacromolecule for the preparation of biocomposites. The synthesis of BSA@ZIF-8 was performed using a twin-screw extruder ZE 12 HMI (Three-Tec Gmbh) at a mild temperature of 40 °C. Automatic volumetric feeder ZD 12B (Three-Tec GmbH) was used to supply the reagent mixture consisting of 2-methylimidazole, zinc source, and BSA. To initiate the reaction, a catalytic amount of EtOH was added using a peristaltic pump BT-L (Lead Fluid, China). Powder X-Ray diffraction (PXRD), thermogravimetric analysis (TGA), FTIR, and N2 adsorption were used to characterize the extrudates.
Highly crystalline and pure BSA@ZIF-8 with different BSA loadings was isolated after washing the extrudate with EtOH and sodium dodecyl sulfate. The EtOH feeding rate was optimized by following the protein encapsulation efficiency at a BSA mass fraction of 10%. A continuous extruder operation under optimized conditions showed good reproducibility and capability of producing biocomposites on the kilograms scale. These results provide highly valuable information for cheap and large-scale production of ZIF-8-based biocomposites. Due to the lack of restrictions on molecule size and solubility, our proof-of-concept study may significantly expand the selection of biomolecules for immobilization in ZIF-8, making the method applicable to various functional applications
T2 - SALSA Make and Measure conference
CY - Berlin, Germany
DA - 13.09.2023
KW - In situ Raman
KW - Large-scale processing
KW - Reactive extrusion
KW - Large-scale production
KW - Mechanochemistry
PY - 2023
AN - OPUS4-58953
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Emmerling, Franziska
T1 - Investigating the mechanism and kinetics of the mechanochemical synthesis of multi-component systems
N2 - Mechanochemistry is a promising and environmentally friendly approach for synthesizing (novel) multicomponent crystal systems. Various milling parameters, such as milling frequency, milling time, and ball diameter have been shown to influence the mechanisms and rates of product formation. Despite increasing interest in mechanochemistry, there is still limited understanding of the underlying reactivity and selectivity mechanisms.
Various analytical techniques have been developed to gain insight into the mechanochemical transformations, including powder X-ray diffraction, X-ray adsorption spectroscopy, NMR, Raman spectroscopy and thermography. Using these techniques, we have studied the formation of (polymorphic) cocrystals, organometallic compounds and salts, and elucidated the influence of milling parameters and reaction sequences on the formation mechanism and kinetics.
For example, our study of the mechanochemical chlorination reaction of hydantoin revealed that normalisation of the kinetic profiles to the volume of the grinding ball clearly showed that physical kinetics dominate the reaction rates in a ball-milling transformation. Attempts to interpret such kinetics in purely chemical terms risk misinterpretation of the results.
Our results suggest that time-resolved in situ investigation of milling reactions is a promising way to fine-tune and optimise mechanochemical processes.
T2 - ISIC 2023
CY - Glasgow, Scotland
DA - 05.09.2023
KW - Mechanochemistry
KW - Polymorphy
KW - In situ
PY - 2023
AN - OPUS4-59023
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Emmerling, Franziska
T1 - Understanding mechanochemical reactions: Real-time insights and collaborative research
N2 - Mechanochemistry emerges as a potent, environmentally friendly, and straightforward approach for crafting novel multicomponent crystal systems. Various milling parameters, including milling frequency, time, filling degree of the milling jar, ball diameter, vessel size, degree of milling ball filling, and material of jars, are recognized influencers on the mechanisms and rates of product formation. Despite the growing interest in mechanochemistry, there exists a gap in understanding the mechanistic aspects of mechanochemical reactivity and selectivity. To address this, diverse analytical methods and their combinations, such as powder X-ray diffraction, X-ray absorption spectroscopy, NMR, Raman spectroscopy, and thermography, have been developed for real-time, in situ monitoring of mechanochemical transformations.
This discussion centers on our recent findings, specifically investigating the formation of (polymorphic) cocrystals and metal-organic frameworks. Through these studies, we aim to unravel the impact of milling parameters and reaction sequences on the formation mechanism and kinetics. Notably, in the mechanochemical chlorination reaction of hydantoin, normalizing kinetic profiles to the volume of the milling ball unequivocally demonstrates the conservation of milling reaction kinetics. In this ball-milling transformation, physical kinetics outweigh chemical factors in determining reaction rates. Attempting to interpret such kinetics solely through chemical terms poses a risk of misinterpretation. Our results highlight that time-resolved in situ investigations of milling reactions provide a novel avenue for fine-tuning and optimizing mechanochemical processes.
T2 - Brimingham Green chemsistry
CY - Birmingham, England
DA - 08.09.2023
KW - Mechanochemistry
KW - Green Chemistry
PY - 2023
AN - OPUS4-59024
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Emmerling, Franziska
T1 - Combination of complementary methods For in situ studies
N2 - This talk explores the synergistic application of complementary synchrotron methods for in situ investigations, providing a comprehensive approach to enhance analytical capabilities in materials research and characterization.
T2 - INSYNX - DEUTSCH-BRASILIANISCHER WORKSHOP ON BREAKING BOUNDARIES OF IN SITU SYNCHROTRON X-RAY METHODS
CY - Sao Paulo, Brazil
DA - 06.03.2023
KW - In situ
KW - Synchrotron
PY - 2023
AN - OPUS4-59025
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Emmerling, Franziska
T1 - Understanding mechanochemical reactions: Real-time insights and collaborative research
N2 - Mechanochemistry has become a compelling method for producing (new) molecule s and mate-rials, but the inner workings of the milling jars remain a fascinating mystery. Advances in this field include tailor-made chemical systems and real-time revelations using techniques such as XRD and Raman spectroscopy.
This talk will discuss our recent progress in using X-ray diffraction and sophisticated spectros-copy to observe reactions in various material systems during ball milling and extrusion in real-time.
The complexity of mechanochemical reactions spans multiple scales and requires a holistic ap-proach. The categorisation of reactions by investigative methods precedes the exploration of real-time analysis that reveals macroscopic processes using synchrotron techniques.
During this exploration, one resounding realisation remains: We are on the threshold of under-standing. The complexity of mechanochemistry requires a collective effort, drawing on the ex-pertise of a diverse community. As we unravel the web of mechanochemical phenomena, we acknowledge the collaborative nature of this ongoing journey.
T2 - CMCC Mechanochemistry Discussions
CY - Online meeting
DA - 21.09.2023
KW - Mechanochemistry
KW - In situ
PY - 2023
AN - OPUS4-59026
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Emmerling, Franziska
T1 - Connecting the nodes: networks and networking
N2 - This talk explores the intricate connections between scientists, focusing on the networking dynamics within the realm of metal-organic frameworks (MOFs). The study delves into the collaborative networks formed among scientists, shedding light on the synergistic relationships that contribute to advancements in MOF research.
T2 - WINS School 2023 Frameworks and networks
CY - Blossin, Germany
DA - 02.06.2023
KW - Metal-organic frameworks
PY - 2023
AN - OPUS4-59028
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Witt, Julia
T1 - Exploring innovative Materials and in situ techniques
N2 - Presentation of some projects conducted in recent years related to corrosion studies and research on electrocatalysis. The talk was part of a seminar at the University of Toronto and took place within the framework of a scientific exchange stay.
T2 - Seminar at the University of Toronto
CY - Toronto, Canada
DA - 11.10.2023
KW - Multi-principal element alloys (MPEAs)
KW - Electrocatalysis
KW - Corrosion
KW - Materials acceleration platforms (MAPs)
PY - 2023
AN - OPUS4-59029
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Krüger, Jörg
T1 - Gefährdung durch Röntgenemission bei der UKP-Laser-Materialbearbeitung
N2 - Der Vortrag gibt einen Überblick zu ultrakurzen Laserpulsen, der Ultrakurzpulslaser-Materialbearbeitung und der dabei ggf. auftretenden unerwünschten Röntgenstrahlung. Es wird die Laserbearbeitung von technischen und biologischen Materialien diskutiert. Schutzmöglichkeiten gegenüber der Röntgenstrahlung werden erörtert.
T2 - Sonthofer Strahlenschutztage 2024
CY - Sonthofen, Germany
DA - 11.03.2024
KW - Ultrakurzpulslaser
KW - Laser-induzierte Röntgenstrahlung
KW - Materialbearbeitung
KW - Technische Materialien
KW - Biologische Anwendungen
PY - 2024
AN - OPUS4-59667
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Czerski, Jakub
A1 - Mitoraj-Krolikowska, Marzena
A1 - Godlewska, Elzbieta
A1 - Wetzel, Annica
A1 - Witt, Julia
A1 - Ozcan, Ozlem
A1 - Marzec, Mateusz
A1 - Goly, Marcin
T1 - Corrosion and passivation of AlCrFe2Ni2Mox high-entropy alloys in sulphuric acid
N2 - Corrosion behaviour of AlCrFe2Ni2Mox (x = 0.0, 0.1, 0.15, 0.3 and 0.6) high-entropy alloys was investigated in a 0.1 M H2SO4 solution. Passive films formed upon anodic polarisation, built of Al-based inner layer and (Cr, Fe, Mo)-based outer layer, had good protective properties. In particular, they prevented corrosion of the (Al, Ni)-rich BCC-B2 phase, which was observed under open-circuit conditions. Moderate amounts of Mo, up to x = 0.3, positively affected the passivation ability of AlCrFe2Ni2. Significant changes in microstructure and phase composition of the alloy at higher Mo concentrations (x = 0.6) resulted in deterioration of its corrosion resistance.
KW - EIS
KW - Alloy
KW - Sulphuric acid
KW - AFM
KW - Acid corrosion
KW - Passive films
PY - 2024
DO - https://doi.org/10.1016/j.corsci.2024.111855
SN - 0010-938X
VL - 229
SP - 1
EP - 17
PB - Elsevier Ltd.
AN - OPUS4-59703
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Brockmann, N.
A1 - Sicken, A.
A1 - Krüger, Jörg
T1 - Effects of laser cleaning on the condition of different silk model samples using varying wavelengths and pulse durations
N2 - The cleaning of aged silk fibers poses a common challenge in the conservation of textiles, since traditional cleaning techniques often yield unsatisfactory results or even harm objects. In this regard, cleaning objects with laser radiation is a promising addition to the range of available methods. Due to it being contactless, even brittle and touch-sensitive objects with disfiguring or harmful soiling could potentially be cleaned and therefore made accessible for research and presentation. Examples of treatment have sometimes shown spectacular results. Still there is some skepticism concerning the safety of this treatment for textile materials, which has been strengthened through previous 532 nm wavelength nanosecond laser cleaning studies on silk fibers. Taking these published results into account, the range of examined laser parameters has been extended in this study, from 532 nm nanosecond laser to 1064 nm nanosecond and even 800 nm femtosecond laser, reevaluating the effect of this treatment on the fibers. The physicochemical processes taking place on the silk fibers when cleaning with lasers are complex and still not fully understood. The aim of this project was therefore to bring more clarification about potential effects of those processes on the condition of silk samples treated with a set of different parameters for wavelength, pulse duration, energy density and number of pulses per spot. It also looks at the influence of the presence of soiling on the results. The analysis of potential effects was then carried out using statistical methods and advanced analytics. Scanning electron microscopy, Fourier-transform infrared spectroscopy and colorimetry technology provided the required insights to better assess the effects. Results show that laser cleaning of silk fibers, like most other conventional cleaning techniques, is not completely without risk, but knowing what the possible effects are helps making decisions on whether the benefits of the technique used justify these risks.
KW - Laser cleaning
KW - Cultural heritage
KW - Conservation
KW - Silk
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594601
DO - https://doi.org/10.1186/s40494-024-01152-1
SN - 2050-7445
VL - 12
IS - 1
SP - 1
EP - 15
PB - Springer
AN - OPUS4-59460
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stawski, Tomasz
A1 - Karafiludis, Stephanos
A1 - Pimentel, Carlos
A1 - Montes-Hernández, German
A1 - Kochovski, Zdravko
A1 - Bienert, Ralf
A1 - Weimann, Karin
A1 - Emmerling, Franziska
A1 - Scoppola, Ernesto
A1 - Van Driessche, Alexander E.S.
T1 - Solution-driven processing of calcium sulfate: The mechanism of the reversible transformation of gypsum to bassanite in brines
N2 - Here, we show that calcium sulfate dihydrate (gypsum) can be directly, rapidly and reversibly converted to calcium sulfate hemihydrate (bassanite) in high salinity solutions (brines). The optimum conditions for the efficient production of bassanite in a short time (<5 min) involve the use of brines with c(NaCl) > 4 M and maintaining a temperature, T > 80 °C. When the solution containing bassanite crystals is cooled down to around room temperature, eventually gypsum is formed. When the temperature is raised again to T > 80 °C, bassanite is rapidly re-precipitated. This contrasts with the better-known behaviour of the bassanite phase in low-salt environments. In low-salinity aqueous solutions, bassanite is considered to be metastable with respect to gypsum and anhydrite, and therefore gypsum-to-bassanite conversion does not occur in pure water. Interestingly, the high-salinity transformation of gypsum-to-bassanite has been reported by many authors and used in practice for several decades, although its very occurrence actually contradicts numerical thermodynamic predictions regarding solubility of calcium sulfate phases. By following the evolution of crystalline phases with in situ and time-resolved X-ray diffraction/scattering and Raman spectroscopy, we demonstrated that the phase stability in brines at elevated temperatures was inaccurately represented in the thermodynamic databases. Most notably for c(NaCl) > 4 M, and T > 80 °C gypsum becomes readily more soluble than bassanite, which induces the direct precipitation of the latter from gypsum. The fact that these transformations are controlled by the solution provides extensive opportunities for precise manipulation of crystal formation. Our experiments confirmed that bassanite remained the sole crystalline phase for many hours before reverting into gypsum. This property is extremely advantageous for practical processing and efficient crystal extraction in industrial scenarios.
KW - Industrial and Manufacturing Engineering
KW - Strategy and Management
KW - General Environmental Science
KW - Renewable Energy, Sustainability and the Environment
KW - Building and Construction
KW - Calcium sulfate
KW - Gypsum
KW - Bassanite
KW - Scattering
KW - Raman
KW - In situ
KW - Synchrotron
KW - BESSY
KW - MySpot
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594698
UR - https://www.sciencedirect.com/science/article/pii/S0959652624004591#appsec1
DO - https://doi.org/10.1016/j.jclepro.2024.141012
SN - 0959-6526
VL - 440
SP - 1
EP - 12
PB - Elsevier B.V.
AN - OPUS4-59469
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mrkwitschka, Paul
A1 - Rühle, Bastian
A1 - Kuchenbecker, Petra
A1 - Löhmann, Oliver
A1 - Lindemann, Franziska
A1 - Hodoroaba, Vasile-Dan
T1 - Embedding and cross-sectioning as a sample preparation procedure for accurate and representative size and shape measurement of nanopowders
N2 - Reliable measurement of the size of polydisperse, complex-shaped commercial nanopowders is a difficult but necessary task, e.g., for regulatory requirements and toxicity risk assessment. Suitable methods exist for the accurate characterization of the size of non-aggregated, stabilized, spherical and monodisperse nanoparticles. In contrast, industrial nanoscale powders usually require dedicated sample preparation procedures developed for the analysis method of choice. These nano-powders tend to agglomerate and/or aggregate, a behavior which in combination with an innate broad particle size distribution and irregular shape often significantly alters the achievable accuracy of the measured size parameters. The present study systematically tests two commercially available nanoscale powders using different sample preparation methods for correlative analysis by scanning electron microscopy, dynamic light scattering, Brunauer–Emmet–Teller method and differential mobility analysis. One focus was set on the sample preparation by embedding nanoparticles in carbon-based hot-mounting resin. Literature on this topic is scarce and the accuracy of the data extracted from cross sections of these particles is unclearly stated. In this paper systematic simulations on the deviation of the size parameters of well-defined series of nanoparticles with different shapes from the nominal value were carried out and the contributing factors are discussed.
KW - Nanopowder
KW - Electron microscopy
KW - Sample preparation
KW - Cross-sectioning
KW - Cerium oxide
KW - Zinc oxide
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593289
DO - https://doi.org/10.1038/s41598-023-51094-0
SN - 2045-2322
VL - 14
SP - 1
EP - 10
PB - Springer Nature
CY - London
AN - OPUS4-59328
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zuffa, Caterina
A1 - Cappuccino, Chiara
A1 - Casali, Lucia
A1 - Emmerling, Franziska
A1 - Maini, Lucia
T1 - Liquid reagents are not enough for liquid assisted grinding in the synthesis of (AgBr)(n-pica) n
N2 - This study investigates the mechanochemical reactions between AgBr 3-picolylamine and 4-picolylamine. The use of different stoichiometry ratios of the reagents allows [(AgBr)(n-pica)]n and [(AgBr)2(n-pica)]n to be obtained, and we report the new structures of [(AgBr)2(3-pica)]n and [(AgBr)2(4-pica)]n which are characterized by the presence of the following: (a) infinite inorganic chains, (b) silver atom coordinated only by bromide atoms and (c) argentophilic interactions. Furthermore, we studied the interconversion of [(AgBr)(n-pica)]n/[(AgBr)2(n-pica)]n by mechanochemical and thermal properties. The in situ experiments suggest that [(AgBr)(3-pica)]n is kinetically favoured while [(AgBr)2(3-pica)]n is converted into [(AgBr)(3-pica)]n only with a high excess of the ligand. Finally, the liquid nature of the ligands is not sufficient to assist the grinding process, and the complete reaction is observed with the addition of a small quantity of acetonitrile.
KW - Mechanochemistry
KW - Complex
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594755
DO - https://doi.org/10.1039/d3cp04791a
SN - 1463-9076
SP - 1
EP - 10
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-59475
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Krüger, Jörg
T1 - Röntgenstrahlungsexposition bei der Anwendung von Ultrakurzpulslasern in der Medizin
N2 - Die Laserbearbeitung von Materialien mit ultrakurzen Laserpulsen kann zu einer sekundären Emission gefährlicher Röntgenstrahlen führen. Dieser Effekt wurde bisher bei der Bearbeitung von technischen Materialien wie Metallen beobachtet. Die Röntgenemission bei der abtragenden Bearbeitung von biologischen Geweben ist noch weitgehend unerforscht. Der Vortrag präsentiert erste Untersuchungen und Ergebnisse des radiologischen Gefährdungspotentials bei der medizinischen Anwendung von Ultrakurzpulslasern am Menschen.
T2 - Bayerische Laserschutztage 2024
CY - Nuremberg, Germany
DA - 17.01.2024
KW - Ultrakurzpulslaser
KW - Laser-induzierte Röntgenstrahlung
KW - Medizinische Anwendung
KW - Auge
KW - Zahn
PY - 2024
AN - OPUS4-59399
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Sediqi, Salmin
A1 - Ozcan, Ozlem
A1 - Witt, Julia
T1 - Multi-principal element alloy nanoparticle (MPEA-NP) electrocatalysts prepared by pulsed laser ablation for electroreduction of CO2
N2 - Multi-principal element alloy (MPEA) nanoparticle electrocatalysts have the potential to provide a cost-effective and efficient alternative to noble metal electrocatalysts. The chemically complex nature and the high configurational entropy of MPEAs offer advantages in tailoring catalytic activity, product selectivity, and improved stability under harsh reaction conditions. Cu-containing bimetallic catalyst systems have already been demonstrated to lead to a significant increase in catalytic efficiency compared to monometallic systems. Thus, this project aims at the design of Cu-containing MPEAs and nanoparticle electrocatalysts for carbon dioxide reduction reaction.
In this project, base alloys were prepared by means of arc melting with subsequent homogenization treatments and processed by pulsed laser ablation in water and organic solvents into high-purity nanoparticles. The nanoparticles were characterized by means of transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). Electrochemical testing was performed both on bulk alloy samples and nanoparticle film coated glassy carbon electrodes by means of cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Nanoparticle coated electrodes have been investigated by means of atomic force microscopy (AFM) and scanning kelvin probe force microscopy (SKPFM) to assure a homogeneous distribution on the electrode surface. The presentation will summarize our initial results on the electrocatalytic activity of Cu-MPEA system for carbon dioxide reduction.
T2 - OPERANDO SPM 2023
CY - Berlin
DA - 15.11.2023
KW - Chemically Complex Materials
KW - CCMat
KW - Electrocatalysis
PY - 2023
AN - OPUS4-59402
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Sediqi, Salmin
A1 - Ozcan, Ozlem
A1 - Witt, Julia
T1 - Multi-principal element alloy nanoparticle (MPEA-NP) electrocatalysts prepared by pulsed laser ablation for electroreduction of CO2
N2 - The motivation and overall objective of the project are to develop electrocatalysts that are free of noble metals (e.g., Pt or Au) and are instead based on medium and high entropy alloys (MEA\HEA) of transition metals for the electrochemical reduction of CO2.
The MEA\HEA are multi principal element alloys (MPEAs) consisting of more than three elements with almost equal alloying proportions, forming solid solutions without intermetallic phases. In such a crystal structure, the individual elements are well mixed, and each atom has different nearest neighbours. In catalysis, especially in selectivity, it is precisely this atomic chaos that matters. Due to the large number of possible combinations of elements, these materials offer excellent conditions to tune their functional properties for specific applications.
Especially, catalyst systems in which Cu is combined with another metallic component show a significant increase in catalytic efficiency compared to monometallic systems. Since the catalytic activity, selectivity, and stability of electrocatalysts strongly depend on the size and surface, systematic studies on the influence of the organic stabilizers on heterogeneous catalysis are also of interest.
The focus of this project is to design Cu-based MEA\HEA electrocatalysts on the atomic level. For this purpose, base alloys will be prepared, processed into high-purity nanoparticles by pulsed laser ablation, and tested as electrocatalysts.
T2 - Tag der Chemie 2023
CY - Berlin, Germany
DA - 05.07.2023
KW - Chemically Complex Materials
KW - CCMat
KW - Electrocatalysis
PY - 2023
AN - OPUS4-59403
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Yesilcicek, Yasemin
A1 - Wetzel, Annica
A1 - Witt, Julia
A1 - Stephan-Scherb, C.
A1 - Ozcan, Ozlem
T1 - Investigation on gradient Fe-Ni-Cr-Mn alloy using diffusion multiples
N2 - The high-throughput synthesis and characterization of potential material combinations plays an important role in accelerating the development of new materials. Diffusion controlled synthesis of gradient alloys is widely used to create phase diagrams, and it is also one of the most effective combinatorial approaches for rapid realization of potential material combinations.
This study focuses on the synthesis and investigation of the quaternary multi-principle-element alloy (MPEA) FeNiCrMn by means of diffusion multiples, the correlation of their microstructural and chemical characterization data with their application relevant properties like local mechanical and corrosion properties. A diffusion system was set up by combining an equimolar ternary alloy (FeNiCr) with a single diffusing metallic component (Mn) with the highest interdiffusion coefficient. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to collect microstructural and compositional information which were correlated to local mechanical properties studied with nanoindentation. Local corrosion properties were investigated by means of Atomic Force Microscopy (AFM) and Scanning Electrochemical Microscopy (SECM). We have observed that a >50 μm deep homogeneous diffusion zone was formed the thickness of which scales with the duration of the thermal treatment. Beyond the Mn-concentration gradient in the FeNiCr matrix, a distinct Cr-rich secondary phase, characterized by high hardness and elastic modulus values appeared. We synthesized MPEAs with selected compositions from the diffusion zone as well as the Cr-rich phase as bulk alloys for electrochemical corrosion studies under different environmental conditions. The presentation will summarize the results of our correlative study on the mechanical properties and corrosion resistance of the quaternary multi-principle-element alloy (MPEA) FeNiCrMn family.
T2 - MRS Spring 2023
CY - San Francisco, California, USA
DA - 10.04.2023
KW - Chemically Complex Materials
KW - CCMat
KW - Diffusion multiples
PY - 2023
AN - OPUS4-59404
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Wetzel, Annica
A1 - Morell, D.
A1 - Ozcan, Ozlem
A1 - Witt, Julia
T1 - The Interplay of Anodic Passivation and Oxygen Evolution of Medium Entropy Alloys in Aqueous NaCl Electrolytes at Different pH
N2 - Due to their favorable mechanical and anti-corrosion properties, medium entropy alloys (MEA) are of high academic and industrial interest as novel materials for engineering and catalytic applications. Previous studies on general corrosion behavior indicate high current densities at high anodic potentials for MEAs. Further investigations of the underlying transpassive dissolution and local corrosion behavior remain scarce.
To understand the passivation behavior of MEAs CrCoNi and FeCrNi at high anodic potentials, the mechanisms of transpassive dissolution and the oxygen evolution reaction were investigated in this project. Scanning electrochemical microscopy (SECM) was applied in the interrogative mode for the detection of evolving metal species and oxygen. By means of ICP-MS analysis, dissolved metal species were quantified to provide a fundamental understanding on the transpassive dissolution. As the oxygen evolution reaction (OER) may contribute a large percentile to the observed current at high anodic potentials, SECM measurements were employed to analyze the onset of the OER. Potentiodynamic, potentiostatic and chronoamperometric techniques as well as different electrolytes were used to induce precisely controlled corrosion loads during the SECM experiments and for the ICP-MS analysis. Macroscopic corrosion properties of the alloys, electrical and chemical properties of the passive films were studied by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and X-Ray Photoelectron Spectroscopy (XPS), respectively.
Finally, the analysis of the corrosion morphology and the potential of the surface before, during and after passivity breakdown was carried out by means of in-situ atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM). The presentation will summarize our results on the interplay of anodic passivation and oxygen evolution of MEAs in aqueous NaCl electrolytes.
T2 - MRS Spring 2023
CY - San Francisco, California, USA
DA - 10.04.2023
KW - Chemically Complex Materials
KW - CCMat
KW - Corrosion
PY - 2023
AN - OPUS4-59405
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Wetzel, Annica
A1 - Yesilcicek, Yasemin
A1 - Witt, Julia
A1 - Ozcan, Ozlem
T1 - Old materials, new life: Using diffusion-controlled synthesis for discovery of novel alloy systems
N2 - Multi principal element alloy (MPEAs) concept allows us to rethink how we develop application-tailored, sustainable materials. The vast composition space leads to nearly indefinite material combinations and will facilitate finding Pareto optimal materials with lower CO2 footprint and avoidance of critical minerals as design criteria. To probe this large compositional space efficiently, the use high-throughput screening methods is inevitable. Diffusion-controlled synthesis of gradient materials is the optimal technique for screening complex compositional materials that would otherwise require comprehensive modelling or experimental efforts.
In this study, we have used a series of diffusion couples of pure metals and alloys with the aim to create a materials library with correlated data on composition and microstructure. With future recycling prospects in mind, and possible applications of Cu containing alloys in electrocatalytic carbon dioxide reduction and antimicrobial alloys we have generated diffusion couples of brass (Cu63Zn37) and bronze (Cu89Sn11) with either pure metals (Fe, Ni, etc.) or with binary or ternary alloys (FeNi, FeNiCr etc.). For different diffusion times and temperatures, we calculated diffusion constants for the material combinations. Following a detailed characterisation of the gradient materials, we have investigated general and local corrosion properties, electrocatalytic activity for oxygen evolution reaction (OER) and carbon dioxide reduction reaction (CRR) as well as mechanical properties (hardness, elastic modulus) on single-phase alloys synthesized in bulk by means of vacuum arc-melting based on the selected local compositions.
In most cases, due to the short diffusion times, the contact between the diffusion couples lead to two separate diffusion zones and thus, different alloy families on both sides. Especially with ternary alloys, interesting selective diffusion processes and unexpected repulsion effects were observed. The presentation will provide an overview of the gradient materials with a focus on the functional properties of single-phase alloy families derived from them.
T2 - MRS Spring 2023
CY - San Francisco, California, USA
DA - 10.04.2023
KW - Chemically Complex Materials
KW - CCMat
KW - Corrosion
KW - Electrocatalysis
PY - 2023
AN - OPUS4-59406
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Yesilcicek, Yasemin
A1 - Wetzel, Annica
A1 - Witt, Julia
A1 - Dimper, Matthias
A1 - Ozcan, Ozlem
T1 - Corrosion and mechanical properties of multi principal element alloys designed by using diffusion couples
N2 - The efficient exploration of novel alloy chemistries is crucial for advancing the development of new materials. Diffusion-controlled synthesis of gradient alloys is an intelligent approach for creating phase diagrams and to effectively identify potential material combinations with tailored properties.
This project focusses on the design of quaternary multi-principle-element alloys (MPEAs) using diffusion couples. Our diffusion system contains an equimolar ternary alloy (FeNiCr) and additional single diffusing elements e.g. Mn and Mo. We determined the optimal temperature ranges for the diffusion thermal treatment by means of ThermoCalc simulations with the aim to form single-phase MPEAs. Microstructure and chemical characterization of the diffusion couples were performed by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). For most alloy couples, the diffusion zone contained a single-phase alloy matrix with diffusion-induced compositional gradient as well as precipitation phases. This heterogeneity makes the diffusion couples interesting materials to investigate local mechanical and corrosion properties. Thus, local corrosion properties were examined using Atomic Force Microscopy (AFM) and Scanning Electrochemical Microscopy (SECM). Nanoindentation was used for the analysis of local mechanical properties.
Based on the results of the local corrosion analysis, we have selected single-phase alloy chemistries along the diffusion zone and reproducibly synthesized these alloys in bulk for detailed corrosion studies by means of potentiodynamic polarization and SECM.
The presentation will briefly summarize our methodology and motivation for using diffusion couples as an efficient tool for exploring phase diagrams of MPEAs in the search for new alloy chemistries and the results of our correlative study on the mechanical and corrosion properties of these materials.
T2 - 244th ECS Meeting
CY - Gothenburg, Sweden
DA - 08.10.2023
KW - Chemically Complex Materials
KW - CCMat
KW - Corrosion
PY - 2023
AN - OPUS4-59407
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Yesilcicek, Yasemin
A1 - Wetzel, Annica
A1 - Witt, Julia
A1 - Dimper, Matthias
A1 - Ozcan, Ozlem
T1 - Correlation of corrosion and mechanical properties of Fe-Ni-Cr-Mn alloy synthesized by diffusion multiples
N2 - The efficient exploration of novel alloy compositions is crucial for advancing the development of new materials. One widely utilized approach for creating phase diagrams is the use of diffusion-controlled synthesis for gradient alloys. This method is also an effective means for rapidly identifying potential material combinations.
The present study focusses on the exploration of quaternary multi-principle-element alloys (MPEAs) using diffusion multiples. We established a diffusion system by combining an equimolar ternary alloy (FeNiCr) with single diffusing elements Mn and Mo. Using ThermoCalc simulations, we determined suitable temperature ranges where we can expect the formation of single-phase alloys. Depending on the diffusion constants of the selected metals, diffusion times were adjusted to obtain diffusion zones with a depth of greater than 50 μm. Microstructural and compositional information was gathered via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) and correlated to local mechanical properties evaluated by means of nanoindentation. Local corrosion properties were examined using Atomic Force Microscopy (AFM) and Scanning Electrochemical Microscopy (SECM).
Our results indicate that the ThermoCalc simulations have a good predictive power for crystallographic phases. However, especially with the Mn-FeNiCr system, formation of Cr-rich secondary phases were observed, which led to Cr-depletion and thus to localized corrosion processes in the matrix at the vicinity of the secondary phases. Based on the results of the local electrochemical tests, we have selected single-phase compositions along the diffusion zone and synthesized these alloys in bulk for corrosion studies by means of potentiodynamic polarization and SECM.
The presentation will summarize our methodology using diffusion couples as an
efficient tool for exploring compositional spaces of MPEAs in the search for novel single-phase alloys and the results of our correlative study on the mechanical and corrosion properties of these materials.
T2 - EUROCORR2023
CY - Brussels, Belgium
DA - 27.08.2023
KW - Chemically Complex Materials
KW - CCMat
KW - Corrosion
PY - 2023
AN - OPUS4-59408
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Ozcan, Ozlem
T1 - Material acceleration platforms (MAPs) - Global activities and developments at BAM
N2 - Die Material Acceleration Platform der BAM (MAPz@BAM) bündelt unsere Automatisierungs-Expertise auf dem Gebiet der Materialwissenschaft und -prüfung. Wir entwickeln modulare Experimentmodule, automatische Prüf- und Auswerteverfahren und setzen künstliche Intelligenz für eine effiziente und autonome Versuchsplanung, - vorhersage und Datenanalyse ein.
T2 - WPFM Expert Group on Structural Materials (EGSM)
CY - Online meeting
DA - 23.05.2023
KW - Material Acceleration Platforms (MAPs)
KW - MAPz@BAM
KW - Self-driving-labs
PY - 2023
AN - OPUS4-59409
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Ozcan, Ozlem
T1 - MAPz@BAM Material Acceleration Plattform Zentrum @ BAM
N2 - Die Material Acceleration Platform der BAM (MAPz@BAM) bündelt unsere Automatisierungs-Expertise auf dem Gebiet der Materialwissenschaft und -prüfung. Wir entwickeln modulare Experimentmodule, automatische Prüf- und Auswerteverfahren und setzen künstliche Intelligenz für eine effiziente und autonome Versuchsplanung, - vorhersage und Datenanalyse ein.
T2 - Kick off Meeting / EnerMAC ZIM Network
CY - Berlin, Germany
DA - 07.12.2023
KW - Material Acceleration Platforms (MAPs)
KW - Self-driving-labs (SDLs)
KW - MAPz@BAM
PY - 2023
AN - OPUS4-59411
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Ozcan, Ozlem
T1 - MAPz@BAM Material Acceleration Plattform Zentrum @ BAM
N2 - Die Material Acceleration Platform der BAM (MAPz@BAM) bündelt unsere Automatisierungs-Expertise auf dem Gebiet der Materialwissenschaft und -prüfung. Wir entwickeln modulare Experimentmodule, automatische Prüf- und Auswerteverfahren und setzen künstliche Intelligenz für eine effiziente und autonome Versuchsplanung, - vorhersage und Datenanalyse ein.
T2 - TechConnect Adlershof: Grand Solutions
CY - Berlin, Germany
DA - 06.11.2023
KW - Material Acceleration Platforms (MAPs)
KW - Self-driving-labs (SDLs)
KW - MAPz@BAM
PY - 2023
AN - OPUS4-59412
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Stawski, Tomasz
A1 - Karafiludis, Stephanos
A1 - Pimentel, C.
A1 - Montes Hernandez, G
A1 - Kochovski, Z
A1 - Bienert, Ralf
A1 - Weimann, Karin
A1 - Emmerling, Franziska
A1 - Scoppola, E
A1 - Van Driessche, A
T1 - Solution-driven processing of calcium sulfate: the mechanism of the reversible transformation of gypsum to bassanite in brines
N2 - Calcium sulfate hemihydrate (CaSO4ᐧ0.5H2O), also known as bassanite, has been used as a precursor to produce gypsum (dihydrate, CaSO4ᐧ2H2O) for various construction and decorative purposes since prehistoric times. The main route to obtain hemihydrate is a thermal treatment of gypsum at temperatures typically between 150 °C and 200 °C to remove some of the structural water.
In this contribution, we introduce (Fig. 1) a more efficient and sustainable method (T < 100 °C) that enables the direct, rapid, and reversibly conversion of gypsum to bassanite using reusable high salinity aqueous solutions (brines with c[NaCl] > 4 M). The optimum conditions for the efficientproduction of bassanite in a short time (< 5 min) involve the use of brines with c(NaCl) > 4 M and maintaining a temperature, T > 80 °C. When the solution containing bassanite crystals is cooled down to around room temperature, eventually gypsum is formed. When the temperature is raised again to T > 80 °C, bassanite is rapidly re-precipitated. This contrasts with the typical behaviour of the bassanite phase in low salt environments.
Traditionally, hemihydrate is obtained through a solid state thermal treatment because bassanite is considered to be metastable with respect to gypsum and anhydrite in aqueous solutions, and therefore gypsum-to-bassanite conversion should not occur in water. Its very occurrence actually contradicts numerical thermodynamic predictions regarding solubility of calcium sulfate phases. By following the evolution of crystalline phases with in situ and time-resolved X-ray diffraction/scattering and Raman spectroscopy, we demonstrated that the phase stability in brines at elevated temperatures is inaccurately represented in the thermodynamic databases. Most notably for c(NaCl) > 4 M, and T > 80 °C gypsum becomes readily more soluble than bassanite, which induces the direct precipitation of the latter from gypsum. The fact that these transformations are controlled by the solution provides extensive opportunities for precise manipulation of crystal formation. Our experiments confirmed that bassanite remained the sole crystalline structure for many hours before reverting into gypsum. This property is extremely advantageous for practical processing and efficient crystal extraction in industrial scenarios.
T2 - Granada Münster Discussion Meeting GMDM 10
CY - Münster, Germany
DA - 29.11.2023
KW - Gypsum
KW - Bassanite
KW - Calcium sulfate
KW - Recycling
KW - Scattering
PY - 2024
AN - OPUS4-59162
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Emmerling, Franziska
T1 - Why shaken, not stirred, makes the difference: insights into mechanochemical reactions from in situ investigations
N2 - Mechanochemistry is an effective, environmentally benign, and facile method for the synthesis of new multicomponent crystal systems. Different milling parameters are known to affect the mechanisms and rates of product formation: milling frequency, milling time, filling degree of the milling jar, ball diameter and vessel size, degree of milling ball filling, and material of jars. The increasing interest in mechanochemistry is contrasted by a limited mechanistic understanding of the mechanochemical reactivity and selectivity.
Different analytical methods and their combinations have been developed for the time resolved in situ monitoring of mechanochemical transformations, including powder X-ray diffraction, X-ray adsorption spectroscopy, NMR, Raman spectroscopy, and thermography.
Here we will discuss our recent results investigating the formation of (poly-morphic) cocrystals[1,3], metal-organic compounds, and salts, thereby elucidating the influence of milling parameters and reaction sequences on the formation mechanism and kinetics. For the mechanochemical chlorination reaction of hydantoin normalizing the kinetic profiles to the volume of the milling ball showed clearly that milling reaction kinetics are conserved. Here physical kinetics dominate reaction rates in a ball-milling transformation. Attempting to interpret such kinetics in purely chemical terms risk misinterpreting the results.
Our results indicate that time-resolved in situ investigation of milling reactions offer a new approach to tune and optimize mechanochemical processes.
T2 - GdCh Vortrag Universität Potsdam
CY - Potsdam, Germany
DA - 05.06.2023
KW - Mechanochemistry
KW - In Situ
PY - 2023
AN - OPUS4-58982
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hodoroaba, Vasile-Dan
T1 - Liaison of ISO/TC 202 Microbeam Analysis with VAMAS/TWA 37 Quantitative Microstructural Analysis
N2 - The progress in activities on Microbeam Analysis under VAMAS/TWA 37 is reviewed. Particularly the liaison with the new projects within the ISO technical committee TC 202 is presented and discussed with respect to the identification and launching corresponding VAMAS projects. The ongoing project "FIB sample processing for TEM" is presented in detail.
T2 - 30th Meeting of ISO/TC 202 Microbeam Analysis
CY - Berlin, Germany
DA - 22.11.2023
KW - VAMAS
KW - ISO/TC 202
KW - Microbeam Analysis
KW - Standardisation
KW - Electron microscopy
KW - FIB
PY - 2023
AN - OPUS4-58984
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - GEN
A1 - Hodoroaba, Vasile-Dan
ED - Hodoroaba, Vasile-Dan
T1 - Liaison Report from ISO/TC 202 'Microbeam Analysis' to ISO/TC 229 'Nanotechnologies'
N2 - Liaison activities within ISO/TC 202 'Microbeam Analysis' which are relevant to ISO/TC 229 'Nanotechnologies' are reported acoording to the structure defined by ISO/TC229 Nanotechnologies Liaisons Coordination Group (NLCG): new standards/documents, coordination issues, and further detailed specific information, e.g. publications, events, comments.
KW - ISO/TC 229 Nanotechnologies
KW - ISO/TC 202 Microbeam Analysis
KW - Standardisation
PY - 2023
SP - 1
EP - 3
CY - ISO, Geneva, CH
AN - OPUS4-58986
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
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593433
DO - https://doi.org/10.1039/D3CY01439H
SN - 2044-4761
SP - 1
EP - 8
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-59343
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - 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
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-589117
DO - https://doi.org/10.1021/acs.jpcc.3c06054
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 - CONF
A1 - Hodoroaba, Vasile-Dan
T1 - SEM/EDS as THE Versatile and Powerful Tool for Micro and Nano Analysis
N2 - The basic principles of generation of electrons and X-rays and the operation of SEM/EDS instruments are presented. Examples, recent successes and challenges in the analysis of nano-structures are given. Multi-method analytical approaches with the focus on imaging the nanoscale are highlighted. Details on the sample preparation and persepective on the automated analysis (sample preparation, measurement, data analyis and storage) are given. Metrological aspects, standardisation, and reference materials are also emphasized by examples.
T2 - Training Course Metrological Determination of Micro and Nano Contaminants in Food
CY - Berne, Switzerland
DA - 05.09.2023
KW - SEM
KW - EDS
KW - Microanalysis
KW - Nanoanalysis
KW - Imaging
PY - 2023
UR - https://www.sem.admin.ch/metas/en/home/dl/kurs_uebersicht/micro_nano_contaminants_in_food.html
AN - OPUS4-58188
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Emmerling, Franziska
A1 - Chewle, S.
A1 - Weber, M.
T1 - Revealing Kinetics of Paracetamol Crystallization Using Time Resolved Raman Spectroscopy, Orthogonal Time-Lapse Photography, and Non-Negative Matrix Factorization (OSANO)
N2 - Crystallization is a complex phenomenon with farreaching implications for the production and formulation of active pharmaceutical ingredients. Understanding this process is critical for achieving control over key physicochemical properties that can affect, for example, the bioavailability and stability of a drug. In this study, we were able to reveal intricate and diverse dynamics of the formation of metastable intermediates of paracetamol crystallization varying with the choice of solvent. We demonstrate the efficacy of our novel approach utilizing an objective function-based non-negative matrix factorization technique for the analysis of time-resolved Raman
spectroscopy data, in conjunction with time-lapse photography.
Furthermore, we emphasize the crucial importance of integrating Raman spectroscopy with supplementary experimental instrumentation for the mathematical analysis of the obtained spectra.
KW - Polymorphism
KW - Crystallization
KW - Measurement
KW - Algorithm
PY - 2023
DO - https://doi.org/10.1021/acs.cgd.3c00617
SN - 1528-7483
VL - 23
SP - 6737
EP - 6746
PB - ACS Publications
AN - OPUS4-58193
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Feiler, Torvid
A1 - Yasuda, N.
A1 - Michalchuk, Adam
A1 - Emmerling, Franziska
A1 - Bhattacharya, Biswajit
T1 - Mechanistic Investigation of an Elastically Flexible Organic Crystal
N2 - Mechanical flexibility in molecular crystals is a fascinating behavior with potential for developing advanced technologies. However, the phenomenon of mechanical bending is poorly understood. We explore for the first time the atomistic origin of elastic bending in a single component organic crystal using a combination of μ-focus synchrotron X-ray diffraction and ab initio simulation.
KW - Flexible crystals
KW - DFT calculation
KW - Bending mechanism
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581949
DO - https://doi.org/10.1021/acs.cgd.3c00473
SN - 1528-7483
VL - 23
IS - 9
SP - 6244
EP - 6249
PB - ACS Publications
AN - OPUS4-58194
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
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582249
DO - https://doi.org/10.1039/D3CC03164K
SN - 1359-7345
VL - 59
IS - 75
SP - 11224
EP - 11227
PB - RSC
CY - Cambridge
AN - OPUS4-58224
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Manzoni, Anna Maria
A1 - Haas, S.
A1 - Kropf, H.
A1 - Duarte, J.
A1 - Cakir, Cafer Tufan
A1 - Dubois, F.
A1 - Többens, D.
A1 - Glatzel, U.
T1 - Temperature evolution of lattice misfit in Hf and Mo variations of the Al 10 Co 25 Cr 8 Fe 15 Ni 36 Ti 6 compositionally complex alloy
N2 - Misfits of γ- γ’ based Al10Co25Cr8Fe15Ni36Ti6 and its Mo- and Hf-variations are studied up to a temperature of 980 °C and compared with Ni- and Co-based superalloys. The trace elements decrease (Hf) or increase (Mo) the edge radii of the γ’ cuboids without changing their sizes. Atom probe measurements revealed that the Hf alloy prefers the γ’ phase while Mo prefers the γ matrix, leading to a lattice parameters enhancement of both phases, as could be revealed by synchrotron X-ray diffraction. The misfit is influenced in opposite ways: Hf increases the positive misfit, while Mo reduces it at all investigated temperatures.
KW - Metal and alloys
KW - Transmission electron microscopy
KW - X-ray diffraction
KW - Atom probe tomography
KW - High entropy alloy
PY - 2020
DO - https://doi.org/10.1016/j.scriptamat.2020.07.013
VL - 188
SP - 74
EP - 79
PB - Elsevier Ltd.
AN - OPUS4-51025
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Röhsler, Andreas
A1 - Sobol, Oded
A1 - Unger, Wolfgang
A1 - Böllinghaus, Thomas
T1 - Comprehensive study of deuterium-induced effects in in austenitic stainless steel AISI 304L
N2 - The damaging impact of hydrogen on the austenitic stainless steel AISI 304 L was analysed.
To this aim, samples were charged electrochemically with the hydrogen isotope deuterium (2H, D) and examined with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and electron backscatter diffraction (EBSD). The fusion of the obtained chemical and structural information revealed local enrichment of deuterium in austenite, transformation into martensite, crack formation and severe roughening of the specimen surface. The results indicated that martensite was not only formed during charging but also during Desorption and ToF-SIMS examinations. Furthermore, cross-sections of deuterium-charged samples revealed that in preferred deformation bands a g/ε/a 0 evolution is taking place.
By means of microscopic analyses and carrier gas hot extraction (CGHE), it was found that the use of NaAsO2 as recombination poison decreased the uptake of hydrogen significantly and resulted in severe precipitation on the specimen surfaces. This is in contrast to the popular presumption that NaAsO2 enhances the uptake of hydrogen (and
deuterium) during electrochemical charging by hampering its recombination from Atoms to molecules.
KW - AISI 304L
KW - Hydrogen
KW - ToF-SIMS
KW - Deuterium
KW - Martensite
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-477540
DO - https://doi.org/10.1016/j.ijhydene.2019.03.058
SN - 0360-3199
SN - 1879-3487
VL - 44
IS - 23
SP - 12228
EP - 12238
PB - Elsevier Ltd.
AN - OPUS4-47754
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -