TY - JOUR
A1 - Yusenko, Kirill
A1 - Petrushina, M.
A1 - Dedova, E.
A1 - Portnaygin, A.
A1 - Papynov, E.
A1 - Filatov, E.
A1 - Gubanov, A.
T1 - Pressure induced change in the ZrWMoO8
N2 - In this paper we report high-pressure synchrotron x-ray powder diffraction data for the cubic ZrWMoO8. For the first time, extensive structural study of ZrWMoO8 solid solution as a function of pressure was performed. This study shows that disordered cubic-ZrWMoO8 (space group Pa) transforms to ordered cubic-ZrWMoO8 (space group P) at low pressure. A further high-pressure influence leads followed by amorphization of the sample at 2.2 GPa. All transformations are irreversible. Our work will have high impact in the design of new composite materials with well-defined thermal expansion, especially for applications under extreme conditions and high mechanic stress.
KW - Phase transition
KW - High-pressure
KW - Complex oxides
PY - 2020
DO - https://doi.org/10.1016/j.matpr.2019.12.141
VL - 25
IS - 3
SP - 428
EP - 430
PB - Elsevier Ltd.
AN - OPUS4-50822
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kanwal, S.
A1 - Ali, Naveed Zafar
A1 - Hussain, R.
A1 - Shah, F.U.
A1 - Akhter, Z.
T1 - Poly-thiourea formaldehyde based anticorrosion marine coatings on Type 304 stainless steel
N2 - In the present study, hexamethylene diisocyanate (HMDI) encapsulated poly-thiourea formaldehyde (PTF) (10 wt%) coating was developed in an epoxy-polyamine matrix and their anticorrosion studies on Type SS304 stainless steel substrate have been conducted using electrochemistry techniques. The compact and hydrophobic shell wall of PTF proved to be a potent shell wall material for HMDI encapsulation. The effect of temperature and pH values was found to be decisive factor in the synthesis of microcapsules. The PTF microcapsules were synthesized in acidic condition with a pH value of 3. Over 90% of the core fraction is retained in water after 21 days immersion. However, core content decreased with increasing temperature. The capsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Electrochemical Impedance spectroscopy (EIS). Scanning electron microscopic analysis depicts the uniform morphology of coating with a particle size in the range of 1.08 µm–22.06 µm.
The vibrational band at 2271 cm−1 attributed to NCO signal further endorses the successful encapsulation of HMDI into the PTF capsules. Electrochemical testing on steel specifies the appreciable anticorrosion performance of the synthesized poly thiourea formaldehyde (PTF) coating against artificial sea water.
KW - In-situ polymerization
KW - Encapsulation
KW - Thiourea-formaldehyde
KW - Marine corrosion
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-507932
DO - https://doi.org/10.1016/j.jmrt.2019.12.045
VL - 9
IS - 2
SP - 2146
EP - 2153
PB - Elsevier B.V.
AN - OPUS4-50793
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Marquardt, Julien
T1 - Investigating the morphology of nanostructured mixed metal oxides (Ir/TiOx) and its impact on the electrocatalytic OER-activity
N2 - The electrocatalytic conversion of water into molecular hydrogen and oxygen under the utilization of excess renewable energies, such as wind power, photovoltaics and hydroelectric power is one possible pathway to establish a sustainable hydrogen economy. The obtained hydrogen is either stored and used in a fuel cell or consumed on-site in industrial applications.
Water electrolysis systems (WES) are based on two half cell reactions, such as oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) which both proceed simultaneously. The OER suffers from slow reaction kinetics and thus limits the overall performance.
The most promising compounds in acidic electrolysis are IrO2 and RuO2. Due to their rare abundance and extremely high price a wide use of acidic WES was prevented. Lowering the catalysts noble metal content by mixing iridium with titanium reduces the production costs.
Thin films are produced by dip coating a solution of metal oxide precursors alongside with a polymer template dissolved in ethanol. The obtained samples are subsequently calcined to the remove the template and adjust crystallinity. Finally, an additional iridium deposition step was performed on the outer surface plane area.
Understanding the influence of structural and morphological aspects on the OER-activity is beneficial to further optimize WES. The current presentation will thus give detailed insights to structural aspects obtained by Raman spectroscopy, small- and wide-angle X-ray scattering which are then combined with electrochemical parameters to deduce structure-activity relationships.
T2 - Joint Polish-German Crystallographic Meeting 2020
CY - Wrocław, Poland
DA - 24.02.2020
KW - nanostructured
KW - electrocatalysis
PY - 2020
AN - OPUS4-50664
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Baláž, M.
A1 - Tešinský, M.
A1 - Marquardt, Julien
A1 - Škrobian, M.
A1 - Daneu, N.
A1 - Rajňák, M.
A1 - Baláž, P.
T1 - Synthesis of copper nanoparticles from refractory sulfides using a semi-industrial mechanochemical approach
N2 - The large-scale mechanochemical reduction of binary sulfides chalcocite (Cu2S) and covellite (CuS) by elemental iron was investigated in this work. The reduction of Cu2S was almost complete after 360 min of milling, whereas in the case of CuS, a significant amount of non-reacted elemental iron could still be identified after 480 min. Upon application of more effective laboratory-scale planetary ball milling, it was possible to reach almost complete reduction of CuS. Longer milling leads to the formation of ternary sulfides and oxidation product, namely cuprospinel CuFe2O4. The rate constant calculated from the magnetometry measurements using a diffusion model for Cu2S and CuS reduction by iron in a large-scale mill is 0.056 min−0.5 and 0.037 min−0.5, respectively, whereas for the CuS reduction in a laboratory-scale mill, it is 0.1477 min−1. The nanocrystalline character of the samples was confirmed by TEM and XRD, as the produced Cu exhibited sizes up to 16 nm in all cases. The process can be easily scaled up and thus copper can be obtained much easier from refractory minerals than in traditional metallurgical approaches.
KW - Mechanochemistry
KW - Copper sulfides
KW - Copper nanoparticles
KW - Magnetometry
KW - Oxidation
PY - 2020
DO - https://doi.org/10.1016/j.apt.2019.11.032
VL - 31
IS - 2
SP - 782
EP - 791
PB - Elsevier B.V.
AN - OPUS4-50665
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Yusenko, Kirill
A1 - Spektor, K.
A1 - Khandarkhaeva, S.
A1 - Fedotenko, T.
A1 - Pakhomova, A.
A1 - Kupenko, I.
A1 - Rohrbach, A.
A1 - Klemme, S.
A1 - Crichton, W. A.
A1 - Dyachkova, T. V.
A1 - Tyutyunnik, A. P.
A1 - Zainulin, Y. G.
A1 - Gramilov, S. A.
A1 - Dubrovinsky, L. S.
T1 - Decomposition of single-source precursors under high-temperature highpressure to access osmium–platinum refractory alloys
N2 - Thermal decomposition of (NH4)2[OsxPt1-xCl6] as single-source precursors for Os-Pt binary alloys has been investigated under ambient and high pressure up to 40 GPa. Thermal decomposition of mixed-metal (NH4)2[OsxPt1-xCl6] precursor in hydrogen atmosphere (reductive environment) under ambient pressure results in formation of β-trans[Pt(NH3)2Cl2] and α-trans-[Pt(NH3)2Cl2] crystalline intermediates as well as single and twophase Os—Pt binary alloys. For the first time, direct thermal decomposition of coordination compound under pressure has been investigated. A formation of pure metallic alloys from single-source precursors under pressure has been shown. Miscibility between fcc- and hcpstructured alloys has been probed up to 50 GPa by in situ high-pressure X-ray diffraction. Miscibility gap between fcc- and hcp-structured alloys does not change its positions with pressure up to at least 50 GPa.
KW - High-pressure high-temperature
KW - Osmium
KW - Platinum
KW - Phase diagrams
KW - Alloys
KW - Single-source precursors
PY - 2020
DO - https://doi.org/10.1016/j.jallcom.2019.152121
VL - 813
SP - 152121
PB - Elsevier
AN - OPUS4-50019
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Medeiros, V.L.
A1 - Goulart de Araujo, L.
A1 - Ratero, D.R.
A1 - Paula, A.S.
A1 - Ferreira Molina, E.
A1 - Jaeger, Christian
A1 - Takehiro Marumo, J.
T1 - Synthesis and physicochemical characterization of a novel adsorbent based on yttrium silicate: A potential material for removal of lead and cadmium from aqueous media
N2 - A new metallosilicate based on yttrium was synthesized and characterized by XRD, FT-IR, 29Si MAS-NMR, and 89Y MAS-NMR. The mixed framework of the material was confirmed by the detection of distinct chemical shift groups using 29Si MAS-NMR (at -82 to -87 ppm, -91 to -94 ppm, -96 to -102 ppm, and -105 to -108 ppm), as well as four distinct chemical shifts in the 89Y MAS-NMR spectrum (at -89, -142, -160, and -220 ppm). Adsorption and kinetic analyses indicated the potential of the new material for the removal of lead and cadmium from aqueous media. The adsorption results for lead indicated that dynamic equilibrium was reached after five hours, with total lead removal of around 94 %, while for cadmium it was reached in the first hour, with total Cadmium removal of around 74 %. The adsorptions of lead and cadmium were modeled using pseudo-first order (PFO) and pseudo-second order (PSO) kinetic models. Although both models provided high R2 values (0.9903 and 0.9980, respectively), the PSO model presented a much lower χ2 red value (4.41×10−4), compared to the PFO model (2.12×10−3), which indicated that the rate-limiting step was probably due to the chemisorption of lead from the solution onto the yttrium-based metallosilicate.
KW - Yttrium silicates
KW - 29Si
KW - 89Y MAS-NMR
KW - Adsorption
KW - Chemisorption
KW - Cadmium and lead remediation
PY - 2020
DO - https://doi.org/10.1016/j.jece.2020.103922
VL - 8
SP - 103922
PB - Elsevier Ltd.
AN - OPUS4-51292
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schiffmann, J.
A1 - Emmerling, Franziska
A1 - Martins, Ines
A1 - Van Wüllen, L.
T1 - In-situ reaction monitoring of a mechanochemical ball mill reaction with solid state NMR
N2 - We present an approach towards the in situ solid state NMR monitoring of mechanochemical reactions in a ball mill. A miniaturized vibration ball mill is integrated into the measuring coil of a home-built solid state NMR probe, allowing for static solid state NMR measurements during the mechanochemical reaction within the vessel. The setup allows to quantitatively follow the product evolution of a prototypical mechanochemical reaction, the formation of zinc phenylphosphonate from zinc acetate and phenylphosphonic acid. MAS NMR investigations on the final reaction mixture confirmed a reaction yield of 89% in a typical example. Thus, NMR spectroscopy may in the future provide complementary information about reaction mechanisms of mechanochemical reactions and team up with other analytical methods which have been employed to follow reactions in situ, such as Raman spectroscopy or X-ray diffraction.
KW - Mechanochemistry
KW - Solid state NMR
KW - NMR probe Development
PY - 2020
DO - https://doi.org/10.1016/j.ssnmr.2020.101687
VL - 109
SP - 101687
PB - Elsevier Inc.
AN - OPUS4-51283
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Usmani, Shirin M.
A1 - Plarre, Rüdiger
A1 - Hübert, Thomas
A1 - Kemnitz, E.
ED - Richter, K.
ED - Van de Kulien, J.-W.
T1 - Termite resistance of pine wood treated with nano metal fluorides
N2 - Fluorides are well-known as wood preservatives. One of the limitations of fluoride-based wood preservatives is their high leachability. Alternative to current fluoride salts such as NaF used in wood protection are low water-soluble fluorides. However, impregnation of low water-soluble fluorides into wood poses a challenge. To address this challenge, low water-soluble fluorides like calcium fluoride (CaF2) and magnesium fluoride (MgF2) were synthesized as nanoparticles via the fluorolytic sol−gel synthesis and then impregnated into wood specimens. In this study, the toxicity of nano metal fluorides was assessed by termite mortality, mass loss and visual analysis of treated specimens after eight weeks of exposure to termites, Coptotermes formosanus. Nano metal fluorides with sol concentrations of 0.5 M and higher were found to be effective against termites resulting in 100% termite mortality and significantly inhibited termite feeding. Among the formulations tested, the least damage was found for specimens treated with combinations of CaF2 and MgF2 with an average mass loss less than 1% and visual rating of “1”. These results demonstrate the efficacy of low water-soluble nano metal fluorides to protect wood from termite attack.
KW - Holzschutzmittel
KW - Nanoparticles
KW - Fluorides
KW - Termites
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514325
DO - https://doi.org/10.1007/s00107-020-01522-z
VL - 78
SP - 493
EP - 499
PB - Springer
CY - Berlin
AN - OPUS4-51432
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - THES
A1 - Kulow, Anicó
T1 - Spatial Resolved Dispersive X-Ray Absorption Spectroscopy and Coded Aperture X-Ray Fluorescence Imaging
N2 - One aim of this work was the development of a new setup for time- and laterally resolved XAFS measurements, based on the pronciple of dispersive XAFS. This setup is scanning free, stable, inexpensive, and straightforward to adjust for probing different elements. The second part of this work describes the impelemntation of a method for full-field X-ray fluorescence imaging with coded apertures. Expensive and complicated X-ray otpics, that are usually used for full-field imaging, are replaced with a coded aperture that consists of many pinholes drilled in an X-ray opaque material. Coded apertures are inexpensive to fabricate, energy independent and easy to use. The working principle is the same as with a pinhole camera, but the multiple holes allow a higher photon flux compared to a single pinhole or even a polycalippary optic, thus alowwing the reduction of measurement time.
KW - X-ray fluorescence imaging
KW - Coded Apertures
KW - X-ray absorption spectroscopy
KW - Synchrotron
PY - 2021
SP - 1
EP - 175
CY - Berlin
AN - OPUS4-52054
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Stawski, Tomasz
T1 - The structure of amorphous calcium sulfate and its role in the nucleation pathway and final mesostructure of CaSO 4 phases
N2 - In recent years, we have come to appreciate the astounding intricacy of the formation process of minerals from ions in aqueous solutions. In this context, a number of studies have already revealed that nucleation in the CaSO4-H2O system is non-classical, where the formation of the different crystalline phases involves several steps including a common amorphous precursor. In this contribution a holistic view of the formation mechanism of gypsum and bassanite from solution will be presented.
In short, our in situ and time-resolved scattering data demonstrate that calcium sulfate precipitation starts with the formation and aggregation of well-defined sub-3 nm primary species. These species constitute building “bricks'' of an amorphous precursor phase. We characterised the “bricks” by combining information obtained at different length-scales accessible at the mesoscale (from small-angle scattering) and at the atomic-length-scale (wide-angle scattering and high-energy diffraction). From these scattering data we derived pair distribution functions of the clusters and restricted their external shapes and dimensions. This allowed us to propose a structure of the primary species and to explore their dynamic properties with unbiased MD simulations using polarizable force fields. The formation of the amorphous phase involves the aggregation of these small primary species into larger disordered aggregates exhibiting “brick-in-the-wall” structure. The actual crystallisation occurs by the restructuring and coalescence of the “bricks” into a given calcium sulfate phase depending on the thermodynamic conditions of the solution. Importantly, these rearrangement processes by no means continue until a (nearly-)perfect homogeneous single crystal is obtained. Instead they come to a stop or at least significantly slow down. Such a process thus yields a final imperfect mesocrystal, composed of smaller domains rather than a continuous crystal structure, within which the domains are separated by an amorphous calcium sulfate phase.
T2 - Goldschmidt Virtual 2021
CY - Online meeting
DA - 04.07.2021
KW - Amorphous calcium sulfate
KW - Scattering
KW - SAXS/WAXS
PY - 2021
UR - https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Paper/3847
AN - OPUS4-53621
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Katsikini, M.
A1 - Filintoglou, K.
A1 - Pinakidou, F.
A1 - Pilatsikas, N.
A1 - Arvanitidis, J.
A1 - Christofilos, D.
A1 - Paloura, E.C.
A1 - Ves, S.
A1 - Reinholz, Uwe
A1 - Papadomanolaki, E.
A1 - Lliopoulos, E.
T1 - Scaling of phonon frequencies and electron binding energies with interatomic distances in InxGa1−xN
N2 - In-K-edge x-ray absorption fine structure (EXAFS), x-ray photoelectron, and Raman spectroscopy results are combined for a comprehensive study of InxGa1−xN layers with energy gaps extending over nearly the whole visible spectrum. The In–N and In–(In,Ga) distances determind by EXAFS are used for the derivation of the In–N bond ionicity as well as for the phonon frequency dependence of the LO and B21 modes, assessed by Raman, and the N 1s, In 3d5/2, Ga 3s, and Ga 2p1/2 electron binding energies on those distances. Phonon confinement due to perturbation of the periodic potential caused by the alloying is also quantified.
KW - Band gap
KW - Phonons
KW - Epitaxy
KW - Electronic structure
KW - X-ray photoelectron
KW - Nitrides
PY - 2021
DO - https://doi.org/10.1063/5.0069359
VL - 130
IS - 20
SP - 205706 - 1
EP - 205706 - 9
PB - AIP Publishing
AN - OPUS4-53956
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Joubert, J.M.
A1 - Crivello, J.C.
A1 - Yusenko, Kirill
T1 - Modification of Lu's (2005) high pressure model for improved high pressure/high temperature extrapolations. Part II: Modeling of osmium-platinum system at high pressure/high temperature
N2 - In Part I of this paper, we have described a modification brought to the model of Lu (X.-G. Lu et al., Comput. Coupling Phase Diagr. Thermochem. 29 (2005) 49–55) in order to avoid extrapolation problems at high pressure and temperature. We now extend this approach to the study of a binary system: Os–Pt. For this, a complete description (equation of state) of Os at high pressure/high temperature is provided including the liquid phase. The thermodynamic assessment of the system Os–Pt has been carried out at ambient pressure by the Calphad method. All this study has been supported by first principles, special quasi-random structure (including under high pressure) and phonon calculations. Finally, using the high pressure description of metastable structures (hcp Pt and fcc Os), we have been able to obtain by extrapolation a complete description of Os–Pt system up to 500 GPa. Recent experimental data for Os–Pt system obtained up to 50 GPa at various temperatures up to 2300 °C may us allow to validate our modeling approach.
KW - Phase diagrams
KW - High-pressure
PY - 2021
DO - https://doi.org/10.1016/j.calphad.2021.102311
VL - 74
SP - 102311
PB - Elsevier
AN - OPUS4-54005
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Fedorova, E.A.
A1 - Asanov, Igor
A1 - Yusenko, Kirill
A1 - Asanova, T.I.
A1 - La Fontaine, Camille
A1 - Roudenko, olga
A1 - Gerasimov, E.Y.
A1 - Vasilchenko, D
A1 - Korenev, S.V.
T1 - Time-resolved study of thermal decomposition process of (NH4)(2) PtCl6 : Intermediates and Pt nucleation
N2 - Evolution in crystal, electronic and local atomic structures of Pt in ammonium hexachloroplatinate in the course of thermal decomposition in inert and reducing atmospheres have been studied by Powder X-Ray Diffraction (PXRD) and Quick X-ray Absorption Fine Structure (QXAFS) at Pt L3-edge for deeper understanding the thermally-induced solid state reaction and the formation of metallic nanoparticles. A three-step thermal decomposition mechanism of (NH4)2[PtCl6] in the inert atmosphere with the intermediate products Pt(NH3)2Cl2 and PtCl2 has been found instead one-[G.Meyer, A.Möller, J. Less. Common. Met. 170 (1991) 327–331] and two-step one [Q.Kong, F.Baudelet, J.Han, S.Chagnot, L.Barthe, J.Headspith, R. Goldsbrough, F.E.Picca, O.Spalla, Sci. Rep. 2 (2012) 1018–1025] considered early. In the reducing atmosphere, the thermal decomposition is a two-step process with the formation of the intermediate PtCl2. The best approach to determining the number of thermal decomposition steps turned out to be the express-analysis of QXAFS spectra offered in the papers, based on the simultaneous presentation of the most important parameters extracted from X-ray Absorption Near Edge Structure (XANES) and Fourier transformed Extended XAFS (EXAFS). This express-analysis was tested by comparison with results of various approaches such as conventional EXAFS fitting, linear combination fit (LCF), Multivariate Curve Resolution Alternating Least Squares method (MCR ALS).
KW - Platinum
KW - Quick-EXAFS
PY - 2021
DO - https://doi.org/10.1016/j.vacuum.2021.110590
VL - 194
SP - 110590
PB - Elsevier
AN - OPUS4-54008
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Asanova, T.I.
A1 - Asanov, Igor
A1 - Yusenko, Kirill
A1 - Le Fontane, Camille
A1 - Gerasimov, E.Y.
A1 - Zadesenetz, A.V.
A1 - Korenev, S.V.
T1 - Time-resolved study of Pd-Os and Pt-Os nanoalloys formation through thermal decomposition of Pd(NH3)(4) OsCl6 and Pt(NH3)(4) OsCl6 complex salts
N2 - The formation mechanisms of Pd-Os and Pt-Os alloys in the course of thermal decomposition of iso-formular and isostructural complex salts [Pd(NH3)4][OsCl6] and [Pt(NH3)4][OsCl6] in an inert atmosphere have been studied by in-situ QXAFS, XPS and PXRD. The mechanisms of thermal decomposition of the precursors are found to differ from each other, but the detected intermediate products show no significant effect on the local atomic structure around Os, Pt/Pd in their final products. A crystalline beta-trans-[Pd(NH3)2Cl2] intermediate of the first step of thermal decomposition of [Pd(NH3)4][OsCl6] makes the anion [OsCl6]2− transform differently than that of [Pt(NH3)4][OsCl6]. It transforms into a short-lived [Os(NH3)xCl6-x] (2≤x≤4), and then to a distorted octahedron [OsCl6]2−, similar to the high-temperature modification of OsCl4. In case of [Pt(NH3)4][OsCl6], the intermediate [Os(NH3)2Cl4] modifies into four chlorine coordinated Os,{OsCl4}0/1−. Consecutive reduction of Pd(II)/Pt(II) and Os(IV) to the metals defines the homophilic atomic order with the fcc-Pd covered by a random Pd-Os alloy layer and Os on the surface, that is supported by High-Resolution Transmission Electron Mictroscopy (HRTEM) and Scanning TEM (STEM) energy dispersive X-ray (EDX) data, and the diffusion direction going from the surface (hcp-Os) to bulk (fcc-Pd/Pt). As a result, the heterogeneous alloys are formed with a very similar electronic and local atomic structure of Os and Pd/Pt. Upon alloying, the Os 5d5/2,3/2 and Pt 5d5/2,3/2 levels are depleted in the Pt-Os alloys compared to dispersed hcp-Os, fcc-Pt, and Pt foil. This is an unusual behaviour for Os and Pt, calling into question the versatility of d-band theory in bimetallic Os-alloys. The spin-orbit effect at the Os site has been found for both the Pd-Os and Pt-Os alloys, but it is about 4 times less compared to the complex salts. The obtained values for the complex compounds are comparable with those for the iridates, proposed as materials with spin-orbit-induced properties.
KW - Thermal decomposition
KW - Quick-EXAFS
PY - 2021
DO - https://doi.org/10.1016/j.materresbull.2021.111511
VL - 144
SP - 111511
PB - Elsevier Ltd.
AN - OPUS4-54010
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Serebrennikova, P.
A1 - Komarov, V.
A1 - Sukhikh, A.
A1 - Khranenko, S.
A1 - Zadesenetz, A.
A1 - Gromilov, S
A1 - Yusenko, Kirill
T1 - [NiEn3](MoO4)0.5(WO4)0.5 co-crystals as single-source precursors for ternary refractory Ni-Mo-W alloys
N2 - The co-crystallisation of [NiEn3](NO3)2 (En = ethylenediamine) with Na2MoO4 and Na2WO4 from a water solution results in the formation of [NiEn3](MoO4)0.5(WO4)0.5 co-crystals. According to the X-ray diffraction analysis of eight single crystals, the parameters of the hexagonal unit cell (space group P–31c, Z = 2) vary in the following intervals: a = 9.2332(3)–9.2566(6); c = 9.9512(12)–9.9753(7) Å with the Mo/W ratio changing from 0.513(3)/0.487(3) to 0.078(4)/0.895(9). The thermal decomposition of [NiEn3](MoO4)0.5(WO4)0.5 individual crystals obtained by co-crystallisation was performed in He and H2 atmospheres. The ex situ X-ray study of thermal decomposition products shows the formation of nanocrystalline refractory alloys and carbide composites containing ternary Ni–Mo–W phases. The formation of carbon–nitride phases at certain stages of heating up to 1000 °C were shown.
KW - Single source precursors
KW - Phase diagrams
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540123
DO - https://doi.org/10.3390/nano11123272
VL - 11
IS - 12
SP - 1
EP - 12
PB - MDPI
CY - Basel
AN - OPUS4-54012
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Yusenko, Kirill
T1 - Single-source precursors strategy to access refractory high-entropy alloys for electrocatalytic applications
N2 - High-entropy alloys containing up to 6 platinum group metals can be prepared by thermal decomposition of single-source precursors non requiring high temperature. We prepare the first example of a single-phase hexagonal high-entropy alloy. Heat treat- ment up to 1500 K and compression up to 45 GPa do not result in phase changes, a record temperature and pres- sure stability for a single-phase high-entropy alloy. The alloys show pronounced electrocatalytic activity in methanol oxidation, which opens a route for the use of high-entropy alloys as materials for sustainable energy conversion.
T2 - HEA2020: first international virtual workshop on high-entropy alloy and complex solid solution nanoparticles for electrocatalysis
CY - Online meeting
DA - 06.10.2020
KW - High-entropy alloys
KW - Single-source precursors
PY - 2020
AN - OPUS4-54013
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Yusenko, Kirill
A1 - Smekhova, A.
A1 - Kuzmin, A.
T1 - Extended X-Ray absorption fine structure (exafs) to study local constitution of high-entropy alloys
N2 - Modern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision.
T2 - SPP2006: ordering in high-entropy alloys
CY - Online meeting
DA - 05.10.2021
KW - EXAFS
KW - High-entropy alloys
PY - 2021
AN - OPUS4-54015
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Rautenberg, Max
T1 - Coordination Polymers for the Applications in Electrochemical Devices
N2 - Coordination polymers can be used as sacrificial templates to prepare nitrogen- and metal doped carbons (NMCs), which are promising catalysts for the oxygen reduction reaction. We at BAM employ mechanochemistry as a "green" synthetic approach to coordiantion polymers, which are throroughly characterized by methods such as XRD, XPS and sorption studies. Our collaborators can prepare NMCs from our coordination polymers and assess the catalytic activity thereof.
T2 - 3rd Training School: "Mechanochemistry: from supramolecular to covalent bonds - synthesis and strctural characterization
CY - Lisbon, Portugal
DA - 22.03.2021
KW - PGM-free catalyst
KW - Mechanochemistry
KW - MOFs
KW - Electrocatalysis
KW - Oxygen reduction reaction (ORR)
PY - 2021
AN - OPUS4-53536
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Halder, A.
A1 - Maiti, A.
A1 - Dinda, S.
A1 - Bhattacharya, Biswajit
A1 - Ghoshal, D.
T1 - Unraveling the Role of Structural Dynamism in Metal Organic Frameworks (MOF) for Excited-State Intramolecular Proton Transfer (ESIPT) Driven Water Sensing
N2 - Ligand based modification has been performed to synthesize a pair of
mixed ligands d10 MOF based materials related to a previously published compound as a base material. The previous compound was a Zn(II)-MOF, {[Zn(4-bpdh)(H2dht)](MeOH)(H2O)}n (1) [N,N′-bis(1-pyridin-4-yl-ethylidene)hydrazine = 4-bpdh and 2,5-dihydroxyterephthalic acid = H4dht], which is a five-fold interpenetrated framework and highly dynamic in nature. In the first synthetic modification, the central metal is replaced by Cd(II), which has the same framework formula as the base material, but this is a rigid compound and also there is no interpenetration in the framework. In the second modification, along with the metal center, the 4,4′- coordinating N,N′-donor ligand is replaced by an isomeric 3,3′-coordinating N,N′- donor linker. In this compound, the dynamism is regenerated. The dynamic nature can be realized by the extensive PXRD studies and characteristic “step-shaped” gas/solvent adsorption behavior for CO2, water, and ethanol. Furthermore, all these 3D MOFs show excited-state intramolecular proton transfer phenomena and water sensing properties in different organic solvents. Here excitingly, the ease of water sensing property is directly related to the dynamic behavior of the framework which has been studied thoroughly in terms of structural correlation.
KW - MOFs
PY - 2021
DO - https://doi.org/10.1021/acs.cgd.1c00446
SN - 1528-7483
VL - 21
IS - 11
SP - 6110
EP - 6118
PB - ACS Publications
AN - OPUS4-53903
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Simões, R. G.
A1 - Melo, P. L. T.
A1 - Bernardes, C. E. S.
A1 - Heilmann, Maria
A1 - Emmerling, Franziska
A1 - Minas da Piedade, M. E.
T1 - Linking Aggregation in Solution, Solvation, and Solubility of Simvastatin: An Experimental and MD Simulation Study
N2 - The solubility is generally thought to be higher if the solvent effectively solvates solute molecules that are well-separated from each other. The present work suggests, however, that the formation of large solute aggregates does not necessarily imply less effective solvation and lower solubility. Measurements of the solubility of simvastatin (one of the most commonly prescribed antihyperlipidemic drugs) in three solvents with different polarities and protic characters, led to the solubility order acetone > ethyl acetate > ethanol, in the full temperature range covered by the experiments (283–308 K). An analysis of the structures of the different solutions on the basis of molecular dynamics simulation results indicated that this trend seems to be determined by a balance between the solute tendency toward aggregation and the ability of the solvent to efficiently solvate it, by integrating the cluster structures, regardless of their size, and effectively establishing solvent–solute interactions.
KW - Simvastatin
KW - Solubility
KW - API
KW - Aggregation
PY - 2021
DO - https://doi.org/10.1021/acs.cgd.0c01325
VL - 21
IS - 1
SP - 544
EP - 551
AN - OPUS4-52185
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Shipov, A.
A1 - Zaslansky, P.
A1 - Riesemeier, Heinrich
A1 - Segev, G.
A1 - Atkins, A.
A1 - Kalish-Achrai, N.
A1 - Weiner, S.
A1 - Shahar, R.
T1 - The influence of estrogen deficiency on the structural and mechanical properties of rat cortical bone
N2 - Background. Post-menopausal osteoporosis is a common health problem worldwide, most commonly caused by estrogen deficiency. Most of the information regarding the skeletal effects of this disease relates to trabecular bone, while cortical bone is less studied. The purpose of this study was to evaluate the influence of estrogen deficiency on the structure and mechanical properties of cortical bone.
Methods. Eight ovariectomized (OVH) and eight intact (control) Sprague Dawley rats were used. Structural features of femoral cortical bone were studied by light microscopy, scanning electron microscopy and synchrotron-based microcomputer-tomography and their mechanical properties determined by nano-indentation.
Results. Cortical bone of both study groups contains two distinct regions: organized
circumferential lamellae and disordered bone with highly mineralized cartilaginous islands. Lacunar volume was lower in the OVH group both in the lamellar and disorganized regions (182 ± 75 µm3 vs 232 ± 106 µm3 , P < 0.001 and 195 ± 86 µm3 vs. 247 ± 106 µm3 , P < 0.001, respectively). Lacunar density was also lower in both bone regions of the OVH group (40 ± 18 ×103 lacunae/mm3 vs. 47 ± 9×103 lacunae/mm3
in the lamellar region, P = 0.003 and 63 ± 18×103 lacunae/mm3
vs. 75 ± 13×103 lacunae/mm3 in the disorganized region, P < 0.001). Vascular canal volume was lower in the disorganized region of the bone in the OVH group compared to the same Region in the control group (P < 0.001). Indentation moduli were not different between the study groups in both bone regions.
Discussion. Changes to cortical bone associated with estrogen deficiency in rats require high-resolution methods for detection. Caution is required in the application of These results to humans due to major structural differences between human and rat bone.
KW - Estrogen
KW - Disorganized bone
KW - Rat
KW - Lacunae
KW - Ovariectomy
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520798
DO - https://doi.org/10.7717/peerj.10213
VL - 9
SP - e10213
AN - OPUS4-52079
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Frisch, M.
A1 - Laun, J.
A1 - Marquardt, Julien
A1 - Arinchtein, A.
A1 - Bauerfeind, K.
A1 - Bernsmeier, D.
A1 - Bernicke, M.
A1 - Bredow, T.
A1 - Kraehnert, R.
T1 - Bridging experiment and theory: enhancing the electrical conductivities of soft-templated niobium-doped mesoporous titania films†
N2 - Theoretical calculations suggest a strong dependence of electrical conductivity and doping concentration in transition-metal doped titania. Herein, we present a combined theoretical and experimental approach for the prediction of relative phase stability and electrical conductivity in niobium-doped titania as model system.
Our method paves the way towards the development of materials with improved electrical properties.
KW - Electrical conductivity
KW - Prediction relative
KW - Transition-metal doped
KW - System method
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521371
DO - https://doi.org/10.1039/d0cp06544g
SN - 1463-9084
VL - 23
IS - 5
SP - 3219
EP - 3224
PB - Royal Society of Chemistry
AN - OPUS4-52137
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Michalchuk, Adam
A1 - Hemingway, J.
A1 - Morrison, C.
T1 - Predicting the Impact Sensitivities of Energetic Materials through Zone-Center Phonon Up-Pumping
N2 - The development of new energetic materials (EMs) is accompanied by significant hazards, prompting interest in their computational design. Before reliable in silico design strategies can be realized, however, approaches to understand and predict EM response to mechanical impact must be developed. We present here a fully ab initio model based in phonon up-pumping which successfully ranks the relative impact sensitivity of a series of organic EMs. The methodology depends only on the crystallographic unit cell and Brillouin zone center vibrational frequencies. We therefore expect this approach to become an integral tool in the large-scale screening of potential EMs.
KW - Energetic materials
KW - Ab initio simulation
PY - 2021
DO - https://doi.org/10.1063/5.0036927
VL - 154
IS - 6
SP - 064105
AN - OPUS4-52146
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Karafiludis, Stephanos
T1 - Crystallisation and nucleation study of transition metal struvite and related compounds
N2 - The recycling of critical elements has crucial importance to maintain sustainable use of raw materials. Phosphorus(P) is a sought-after limited natural resource due to its wide use in modern agriculture mainly as P-fertilizers. But it causes major problems for the environment such as eutrophication of ecosystems. In the future it could be depleted due to the high demand and declining natural phosphorite ore deposits. Therefore, the phosphorus recovery from agricultural waste waters will be an important factor in preservation of the global consumption. The precipitation of M-struvite (NH4MPO4·6H2O, M2+= Mg2+, Ni2+, Co2+, Zn2+, Cu2+ etc.) from agricultural and mine waste waters is a promising P-recovery route. Besides avoidance of eutrophication due to extraction of excess phosphates and the restoration of the phosphorus resources the recovered M-struvites may be potentially be up-cycled for industrial applications e.g. Co and Ni-phosphate show excellent electrochemical properties for batteries or supercapacitors.
The precipitation processes of M-struvites are strongly dependent on the degree of supersaturation, pH and on the exchange ions M2+.The impact of transition metals on the crystallization of M-struvite has been investigated only to a limited extent. An optimization of the reaction conditions could lead to more efficient M-struvite precipitation and significantly improved P-recovery method. In addition, these materials form transitional amorphous colloidal nanophases on the way to the crystalline product indicating a non-classical crystallization pathway. By interfering the crystallization process a potential highly reactive amorphous precursor material can be preserved for electrocatalysis.
Here, we present hints on the crystallization mechanism and the kinetics of precipitation through analysis of the transitional phases. Furthermore, we reveal the effect of different reaction conditions on the crystal shape and crystallite size of M-struvites (NH4MPO4∙6H2O, M = Mg2+, Ni2+, Co2+). In addition, we could evaluate the stability of crystalline M-struvites and their related phases through characterization of the coordination environment [Co-dittmarite (COD) NH4CoPO4∙H2O and Cobalt(II)phosphate octahydrate (CPO) Co3(PO4)2∙8H2O].Due to the low solubility product and their controlled precipitation through adjusting the reaction conditions (c(educts), pH, multi metal solutions) M-struvite is a promising recovery material as it could extract NH4+, PO43- and heavy metals at the same time out of agricultural and mine waste waters.
T2 - IUCr 25th International Union of Crystallography Congress
CY - Online meeting
DA - 14.08.2021
KW - Crystal Engineering
KW - Nucleation
KW - Amorphous Phases
KW - Crystal mechanism
PY - 2021
AN - OPUS4-53445
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Karafiludis, Stephanos
T1 - Crystallisation and nucleation study of transition metal phosphates: M-struvite and related compounds
N2 - The recycling of critical elements has crucial importance to maintain sustainable use of raw materials. Phosphorus(P) is a sought-after limited natural resource due to its wide use in modern agriculture mainly as P-fertilizers. But it causes major problems for the environment such as eutrophication of ecosystems. In the future it could be depleted due to the high demand and declining natural phosphorite ore deposits. Therefore, the phosphorus recovery from mine and agricultural waste waters will be an important factor in preservation of the global consumption. The precipitation of M-struvite (NH4MPO4·6H2O, M2+= Mg2+, Ni2+, Co2+) from waste waters is a promising P-recovery route. Besides avoidance of eutrophication due to extraction of excess phosphates and the restoration of the phosphorus resources the recovered M-struvites may be potentially be up-cycled for industrial applications e.g. Co and Ni-phosphate show excellent electrochemical properties for batteries or supercapacitors.
The precipitation process of M-struvites is strongly dependent on the degree of supersaturation, pH and on the exchange ions M2+.The influence of these precipitation parameters on the crystal morphology and size of transition metal struvite has been investigated only to a limited extent. An optimization of the reaction conditions could lead to more efficient M-struvite precipitation and significantly improved P-recovery method.
We reveal the effect of different reaction conditions on the crystal shape and crystallite size of M-struvites (NH4MPO4∙6H2O, M = Mg2+, Ni2+, Co2+). Furthermore, we characterize the coordination environment of the crystalline end products and their related phases [Co-dittmarite (COD) NH4CoPO4∙H2O and Co(II)phosphate octahydrate (CPO) Co3(PO4)2∙8H2O]. Due to the presence of various amorphous phases pH is changing significantly in the different systems. Mg- and Ni-struvite are stable in multiple concentrations of the educts and metal/phosphorus (M/P) ratios in contrast to Co-struvite which forms below M/P ratios of 0.4. A high M/P ratio with high concentrations of the educts decrease the crystallite size and idiomorphism of the crystals while low M/P ratios with low concentrations of the educts increase the crystallite size and the euhedral formation of the crystal planes. In the (Ni, Co)-solid solutions Ni and Co are homogenously distributed in the crystals with similar Ni# as in the aqueous solutions indicating no elemental fractionation in crystallization. Ni and Co-struvite exhibit a more centrosymmetric coordination environment compared to their related phases of COD and CPO determined by EXAFS. The CoO6 octahedron expands slightly the ideal size of the struvite structure and decomposes to Co-dittmarite. From TEM analysis and pH measurements it is suggested that the crystallization of Ni- and Co-struvite follows a non-classical crystallization theory which consists of multiple nanophases, crystalline or amorphous, on the way to the final crystalline product.
T2 - Goldschmidt Conference 2021
CY - Online meeting
DA - 04.07.2021
KW - Crystal Engineering
KW - Nucleation
KW - Amorphous Phases
KW - Crystal mechanism
PY - 2021
UR - https://2021.goldschmidt.info/goldschmidt/2021/meetingapp.cgi/Paper/5288
AN - OPUS4-53446
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Stawski, Tomasz
T1 - Scattering is a powerful tool to follow nucleation and growth of minerals from solutions
N2 - In recent years, we have come to appreciate the astounding intricacy of the formation process of minerals from ions in aqueous solutions. The original ‘textbook’ image o these phenomena, stemming from the adaptation of classical nucleation and growth theories, has increased in complexity due to the discovery of a variety of precursor and intermediate species [e.g. 1], including solute clusters (e.g. prenucleation clusters PNCs), liquid(-like) phases, as well as amorphous and nanocrystalline solids etc. In general, these precursor or intermediate species constitute different, often short-lived points along the pathway from dissolved ions to the final solids (typically crystals in this context). In this regard synchrotron-based scattering (SAXS/WAXS/HEXD appears to be the perfect tool to follow in situ and in a time-resolved manner the crystallization pathways because of the temporal and spatial length scales that can be directly accessed with these techniques.
Here, I show how we used scattering to probe the crystallization mechanisms o calcium sulfate. CaSO4 minerals (i.e. gypsum, anhydrite and bassanite) are widespread in natural and industrial environments. During the last several years, a number o studies have revealed indeed that nucleation in the CaSO4-H2O system is non-classical My SAXS data demonstrate that gypsum precipitation, involves formation and aggregation of sub-3 nm primary species. These species constitute building blocks o an amorphous precursor phase [2]. Further, I show how in situ high-energy X-ray diffraction experiments and molecular dynamics (MD) simulations can be combined to derive the atomic structure of the primary CaSO4 clusters seen at small-angles [3]. fitted several plausible structures to the derived pair distribution functions and explored their dynamic properties using unbiased MD simulations based on polarizable force fields. Finally, based on combined SAXS/WAXS, broad-q-range measurements, show that the process of formation of bassanite, a less hydrated form of CaSO4, is very similar to the formation of gypsum: it also involves the aggregation of small primary species into larger disordered aggregates [4].
Based on these recent insights I formulated a tentative general model for calcium sulfate precipitation from solution. This model involves primary species that are formed through the assembly of multiple Ca2+ and SO42- ions into nanoclusters. These nanoclusters assemble into poorly ordered (i.e. amorphous) hydrated aggregates which in turn undergo ordering into coherent crystalline units of either gypsum o bassanite (and possibly anhydrite). Determination of the structure and (meta)stability of the primary species is important from both a fundamental, e.g. establishing a general non-classical nucleation model, and applied perspective; e.g. allow for an improved design of additives for greater control of the nucleation pathway
T2 - BAM - Abteilungsseminar 6.3
CY - Online meeting
DA - 21.02.2021
KW - Scattering
KW - SAXS/WAXS
KW - Calcium sulfate
PY - 2021
AN - OPUS4-53713
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Cakir, Cafer Tufan
T1 - Unravelling the depths of complex alloys with grazing exit XANES
N2 - High entropy alloys (HEAs) are considered as a new class of alloys containing at least 5 elements with concentrations between 5 and 35 atomic percent. There has been a growing interest in HEAs in the material research field in recent years. Due to their adjustable composition, which enables the modifications of mechanical properties (such as hardness, strength and ductility etc) and their stability at high temperatures, HEAs have been the focus of various studies.
Especially the corrosion behavior of HEAs has been a wide research interest. Since the grazing exit X-ray fluorescence (GEXRF) offers a non-destructive way to collect notable information regarding the high temperature oxidation, we consider it as a useful method to investigate how HEAs behave in corrosive environments.
The main idea of grazing geometry is to enhance the fluorescence signal of the surface. This enables highly sensitive surface analyses of thin protective film on surface in sub-micrometer scale. Position-sensitive area detectors provide information regarding the signal emitted from the sample as a function of emission angle and thus allow depth-sensitive analysis. Furthermore, the data collected from samples of an incidence energy which lays within a specific energy range provides XANES data to determine oxidation states. Moreover, since GEXRF profiles can also be simulated through physical models (Urbach 1999), they enable us to determine the layer thickness of a given sample in a non-destructive way.
In this contribution, we present the preliminary results of a conceptual study regarding layer properties of CrCoNi medium entropy alloy. The successful implementation of such methodological concept will pave the way for the investigation of more complex alloys with multiple layers, which is planned for the later phases of the project.
T2 - Denver X-Ray Conference DXC 2021
CY - Online meeting
DA - 02.08.2021
KW - GEXRF
KW - High entropy alloys
KW - XANES
KW - Grazing exit
KW - XAS
PY - 2021
AN - OPUS4-54027
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Cakir, Cafer Tufan
T1 - Unrevealing the depths of compositionally complex alloys with grazing exit XANES
N2 - High entropy alloys (HEAs) are considered as a new class of alloys containing at least 5 elements with concentrations between 5 and 35 atomic percent. There has been a growing interest in HEAs in the material research field in recent years. Due to their adjustable composition, which enables the modifications of mechanical properties (such as hardness, strength and ductility etc) and their stability at high temperatures, HEAs have been the focus of various studies.
Especially the corrosion behavior of HEAs has been a wide research interest. Since the grazing exit X-ray fluorescence (GEXRF) offers a non-destructive way to collect notable information regarding the high temperature oxidation, we consider it as a useful method to investigate how HEAs behave in corrosive environments.
The main idea of grazing geometry is to enhance the fluorescence signal of the surface. This enables highly sensitive surface analyses of thin protective film on surface in sub-micrometer scale. Position-sensitive area detectors provide information regarding the signal emitted from the sample as a function of emission angle and thus allow depth-sensitive analysis. Furthermore, the data collected from samples of an incidence energy which lays within a specific energy range provides XANES data to determine oxidation states. Moreover, since GEXRF profiles can also be simulated through physical models (Urbach 1999), they enable us to determine the layer thickness of a given sample in a non-destructive way.
In this contribution, we present the preliminary results of a conceptual study regarding layer properties of CrCoNi medium entropy alloy. The successful implementation of such methodological concept will pave the way for the investigation of more complex alloys with multiple layers, which is planned for the later phases of the project.
T2 - XAFS 2021, The 18th International XAFS Conference
CY - Online meeting
DA - 02.08.2021
KW - GEXRF
KW - High entropy alloys
KW - XANES
KW - Grazing exit
KW - XAS
PY - 2021
AN - OPUS4-54028
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zvereva, V.V.
A1 - Asanov, I.P.
A1 - Yusenko, Kirill
A1 - Zadesenec, A.V.
A1 - Plyusnin, P.E.
A1 - Gerasimov, E.Yu.
A1 - Maksimovskiy, E.A.
A1 - Korenev, S.V.
A1 - Asanova, T.I.
T1 - Local atomic and electronic structure of Pt‑Os nanoplates and nanofbers derived from the single‑source precursor (NH4)2[Pt0.5Os0.5Cl6]
N2 - Abstract Nowadays, Pt-Os binary systems are mainly considered as catalysts and electrocatalysts, but the role of Os in these processes is still poorly understood. The electronic structure of Pt-Os nanosystems remains a few studied as well. Using bimetallic (NH4)2[Pt0.5Os0.5Cl6] as a single-source precursor for preparing Pt-Os nanoalloy through the thermal decomposition in hydrogen and inert atmospheres, the relation of morphology, atomic ordering, and electronic structure of Pt-Os nanoalloy was examined by in situ Quick XAFS, XPS, PXRD, SEM, and HRTEM techniques. Being the only variable parameter, the decomposition atmosphere was found to govern the morphology of the Pt-Os nanoalloy and change the atomic ordering (alloying extent), which involves a change in the electronic structure. In a hydrogen atmosphere, the nanofibers (NFs) (ø ~ 5–6 nm) with the atomic ordering Oscore&Pt-richshell were observed to form; in a nitrogen atmosphere, thin nanoplates (NPLs) (~ 12 nm) with the atomic architecture Os-richcore&Ptrichshell were found out. The depletion in the Os 5d5/2 and Pt 5d5/2,3/2 states was revealed for Pt-Os nanoalloys.
This unusual result disagrees with the known d-band theory and indicates that there is a gain of non-d conduction electron counts at one or both sites. Mixed conductivity may exist in such Pt-Os nanoalloy that may be responsible for a manifestation of new physical properties of this binary system .
KW - Bimetallic alloy
KW - Nanoalloy
KW - Synchrotron radiation
KW - XAFS
KW - Electronic structure
KW - Alloy morphology
PY - 2021
DO - https://doi.org/10.1007/s11051-021-05378-z
SN - 1388-0764
VL - 24
IS - 1
SP - 1
EP - 23
PB - Springer
AN - OPUS4-55347
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Karafiludis, Stephanos
T1 - Trash to treasure: recovery of transition metal phosphates for (electro-)catalytical applications
N2 - Wastewaters containing high concentrations of NH4+, PO43- and transition metals are environmentally harmful and toxic pollutants. At the same time phosphorous and transition metals constitute valuable resources. Here, we report the synthesis routes for Co- and Ni-struvites (NH4MPO4∙6H2O, M = Ni2+, Co2+) out of aqueous solutions resembling synthetic/industrial waste water compositions, and allowing for P, ammonia and metal co-precipitation. Furthermore, the as-obtained struvites were further up-cycled. When heated, these transition metal phosphates (TMPs) demonstrate significant changes in the degree of crystallinity/coordination environment involving a high amount of amorphous phases and importantly develop mesoporosity (Figure 1). In this regard, amorphous and mesoporous TMPs are known to be highly promising (electro-)catalysts.
Amorphous phases do not represent a simple “disordered” crystal but more a complex system with a broad range of compositions and physicochemical properties, which remain mostly unknown. Consequently, we investigated the recrystallization and amorphization process during thermal treatment and a resolved the complex amorphous/crystalline structures (Figure 2). As a proof-of-principle for their applicational use, the as-obtained TMPs demonstrate significant proton conductivity properties similar to apatite-like structures from room to high temperatures (>800°C).
Hence, we have developed a promising recycling route in which environmental harmful contaminants like PO43-, NH4+ and 3d metals would be extracted out of waste waters in the form of precursor raw materials. These raw materials can be then further up-cycled through a simple thermal treatment for their specific application in electrocatalysis.
T2 - Goldschmidt Conference 2022
CY - Hawai'i, USA
DA - 10.07.2022
KW - Mesoporosity
KW - Amorphous phases
KW - Transition metals
KW - Struvite
KW - Phosphates
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552852
UR - https://conf.goldschmidt.info/goldschmidt/2022/meetingapp.cgi/Paper/9501
AN - OPUS4-55285
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Rautenberg, Max
T1 - Ca-MOFs with varying fluorination degree
N2 - In current Li-ion batteries electrode materials consist typically of inorganic materials, such as LiCoO2, LiNixCoyMn1-zO2, LiFePO4, Li4Ti5O12. These materials struggle with toxicity or limited mineral resources, making them expensive. Therefore, eco-friendly, sustainable, and low-cost alternatives are researched for in recent years. A series of organic compounds were investigated as electrode materials for alkali-ion batteries. Among them organic carbonyl-based materials show reversible storage of lithium- or sodium-ions. Metal terephthalates stand out with their easy synthesis, moderate operational voltage and enhanced dissolution stability compared to other organic compounds. One degradation pathway consists of the dissolution of the electrode material by HF, formed in a side reaction by water and the fluorous electrolyte. Fluorinated metal terephthalates could offer higher dissolution stability against HF and less contamination by water due to their increased hydrophobicity.
The goal of this project is the synthesis and the investigation of the formation mechanism of a series of calcium-based MOFs with increasing fluorine content. For this purpose, we aimed for the construction of calcium-based MOFs with terephthalic acid (H2-pBDC), 2-fluoro-terephthalic acid (H2-2F-pBDC), 2,3,4,5-tetrafluoroterephthalic acid (H2-pBDC-F4), isophthalic acid (H2-mBDC) and 5-fluoro-isophthalic acid (H2-5F-mBDC).
T2 - SFB 1349 Wintersymposium 2022
CY - Berlin, Germany
DA - 15.03.2022
KW - Mechanochemistry
KW - Electrode materials
KW - Fluorinated MOFs
KW - In situ PXRD
PY - 2022
AN - OPUS4-54478
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Mishmastnehi, Moslem
A1 - Stawski, Tomasz
T1 - Crystals of Gypsum in Hands of Masters
N2 - The microstructure of most Seljuk and Ilkhanid stucco decorations consists of micrometer-sized crystals of gypsum. The stucco-masters of these periods (neither nowadays stucco-masters) were not able to directly control the properties of these tiny crystals with their hands or centimeter-sized tools. There are, however, traces of chaîne opératoire accumulated in the materialistic body of these pieces, some of which could be explored through an interdisciplinary approach. Such an investigation requires very careful in situ observation of the macrostructure, and scientific analyses of the material to discover part of the production process for each body of stucco. Furthermore, there are deterioration factors, some of which are not yet fully understood, and should be identified using modern analytical instruments. These damaging factors could easily affect the micro and macro structure of a stucco decoration, influencing our interpretation. The concept of chaîne opératoire reframes our questions about the production process and probable dating technique of Seljuk and Ilkhanid stuccoes, while analyses of labmade replicas and historic materials enhance our understanding and interpretation of these materials. Here we present the results of such a study for a large body of Seljuk and Ilkhanid stucco decorations at various sites in Iran, and present the potential of this approach as a new perspective in this field of research.
T2 - Stucco in the Architecture of Iran and Neighbouring Lands
CY - Bamberg, Germany
DA - 04.05.2022
KW - Gypsum
KW - Stuccos
KW - Crystallization
PY - 2022
AN - OPUS4-54782
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hieu, D.T.
A1 - Kosslick, H.
A1 - Riaz, M.
A1 - Schulz, A.
A1 - Springer, A.
A1 - Frank, M.
A1 - Jäger, Christian
A1 - Minh Thu, N.T.
A1 - Son, L.T.
T1 - Acidity and Stability of Bronsted Acid Sites in Green Clinoptilolite Catalysts and Catalytic Performance in the Etherification of Glycerol
N2 - Natural zeolite clinoptilolite CLIN with a framework ratio of Si/Al ≥ 4 containing mainly potassium and calcium ions in its internal channel system was used as a starting material. The acidic HCLIN catalysts were prepared under soft conditions avoiding the use of environmental less benign mineral acids. The starting material was ion exchanged using a 0.2 M aqueous ammonium nitrate solution at a temperature 80 ◦C for 2 h. The obtained NH4CLIN was converted into the acid HCLIN catalyst by calcination at 300–600 ◦C. The obtained samples were characterized by XRD, FTIR, SEM/TEM, AAS, and EDX element mapping. The state of aluminium and silicon was studied by 27Al- and 29SiMAS NMR spectroscopy. The textural properties of the catalysts were investigated by nitrogen adsorption and desorption measurements. The Brønsted acidity of the HCLIN catalysts was studied by temperature-programmed decomposition of the exchanged ammonium ions releasing ammonia as well as 1H MAS NMR, {1H–27Al} Trapdor, and {1H–27Al}
Redor experiments. The strongly agglomerated samples were crystalline and thermally stable up to >500 ◦C. Although a part of the clinoptilolite framework is maintained up to 600 ◦C, a loss of crystallinity is already observed starting from 450 ◦C. The specific surface areas of the starting CLIN and ammonium exchanged NH4CLIN are low with ca. 26 m2/g. The pores are nearly blocked by the exchangeable cations located in the zeolite pores. The thermal decomposition of the ammonium ions by calcination at 400 ◦C causes an opening of the pore entrances and a markable increase in the specific micropore area and micropore volume to ca. 163 m2/g and 0.07 cm3/g, respectively. It decreases with further rising calcination temperature indicating some structural loss. The catalysts show a broad distribution of Brønsted acid sites (BS) ranging from weak to strong sites as indicated the
thermal decomposition of exchanged ammonium ions (TPDA). The ammonium ion decomposition leaving BS, i.e., H+ located at Al–O–Si framework bridges, starts at ≥250 ◦C. A part of the Brønsted sites is lost after calcination specifically at 500 ◦C. It is related to the formation of penta-coordinated aluminium at the expense of tetrahedral framework aluminium. The Brønsted sites are partially recreated after repeated ammonium ion exchange. The catalytic performance of the acidic HCLIN
catalysts was tested in the etherification of glycerol as a green renewable resource with different C1 -C4 alcohols. The catalysts are highly active in the etherification of glycerol, especially with alcohols containing the branched, tertiary alkyl groups. Highest activity is observed with the soft activated catalyst HCLIN300 (300 ◦C, temperature holding time: 1 min). A total of 78% conversion of glycerol to mono and di ether were achieved with tert-butanol at 140 ◦C after 4 h of reaction.
The mono- and di-ether selectivity were 75% and 25%, respectively. The catalyst can be reused.
KW - Etherification
KW - Glycerol
KW - Zeolite
KW - Clinoptilolite
KW - Bronsted acidity
KW - Dehydroxylation
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546982
DO - https://doi.org/10.3390/catal12030253
VL - 12
IS - 3
SP - 1
EP - 24
PB - MDPI
AN - OPUS4-54698
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
ED - Stawski, Tomasz
ED - Van Driessche, A. E. S.
T1 - Special issue "Formation of sulfate minerals in natural and industrial environments"
N2 - Sulfate is abundant in the environment and, as a result, sulfate-containing minerals constitute a large and important focus of research. These minerals play an important role in many geochemical and industrial processes, including the sulfur cycle, the construction industry (e.g., plaster of Paris), fault tectonics, acid mine drainage, and even rare biominerals. Important to note are the abundant amounts of sulfate (minerals) located on the surface of Mars, and in meteorites, extending the relevance of this mineral group beyond the realm of our planet. In geological systems, sulfate minerals such as barite are also important for indicating certain sedimentation environments. In this regard, sulfate deposits can be used to evaluate the redox state of ancient oceans during early Earth time periods.
KW - Calcium sulfate
KW - Sulfates
PY - 2020
UR - https://www.mdpi.com/journal/minerals/special_issues/FSMNIE
SN - 2075-163X
VL - 10(9)-12(3)
SP - 10-812-1
EP - 12-299-3
PB - MDPI
CY - Basel
AN - OPUS4-54700
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stawski, Tomasz
A1 - Van Driessche, A. E. S.
T1 - Editorial for special issue "Formation of sulfate minerals in natural and industrial environments"
N2 - Sulfate is abundant in the environment and, as a result, sulfate-containing minerals constitute a large and important focus of research. These minerals play an important role in many geochemical and industrial processes, including the sulfur cycle, the construction industry (e.g., plaster of Paris), fault tectonics, acid mine drainage, and even rare biominerals. Important to note are the abundant amounts of sulfate (minerals) located on the surface of Mars, and in meteorites, extending the relevance of this mineral group beyond the realm of our planet. In geological systems, sulfate minerals such as barite are also important for indicating certain sedimentation environments. In this regard, sulfate deposits can be used to evaluate the redox state of ancient oceans during early Earth time periods.
KW - Calcium sulfate
KW - Sulfates
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546794
DO - https://doi.org/10.3390/min12030299
SN - 2075-163X
VL - 12(3)
IS - Special issue "Formation of sulfate minerals in natural and industrial environments"
SP - 1
EP - 3
PB - MDPI
CY - Basel
AN - OPUS4-54679
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Madeja, B.
A1 - Gebauer, D.
A1 - Marsiske, M. R.
A1 - Ott, A.
A1 - Rückel, M.
A1 - Rosenberg, R.
A1 - Baken, A.
A1 - Stawski, Tomasz M.
A1 - Fernandez-Martinez, A.
A1 - Van Driessche, A.E.S.
A1 - Cölfen, H.
A1 - Kellermeier, M.
T1 - New insights into the nucleation of portlandite and the effects of polymeric additives
N2 - The crystallization of calcium hydroxide (Ca(OH)2, CH, portlandite) is a key process during the early stages of cement hydration. In the present work, we have revisited the formation of this mineral through nucleation and growth from supersaturated aqueous solutions, in the light of the currently emerging picture of multistage “non-classical” crystallization. To that end, we developed a titration-based assay, in which stock solutions of both relevant ions are added simultaneously into a reservoir, where supersaturation increases slowly at constant stoichiometry until nucleation occurs. This procedure allows both pre- and early post-nucleation phenomena to be analyzed quantitatively. Complementarily, the early stages of portlandite mineralization were probed by various advanced characterization techniques, including cryo-transmission electron microscopy (cryo-TEM), in-situ small-angle X-ray scattering (SAXS), pair distribution function (PDF) analysis of high-energy X-ray scattering (HEXS) data, and analytical ultracentrifugation (AUC). The experimental data show that the formation of calcium hydroxide starts with the association of ions into complexes and clusters, which subsequently coalesce to form amorphous nanoparticles – much like what has been observed in the case of calcium carbonate and other prominent minerals. Subsequently, these particles aggregate and build networks, which eventually transform into hexagonal Ca(OH)2 crystals. The presence of a soluble polycarboxylate – as a known inhibitor of portlandite crystallization – does not change the main characteristics of this multistep nucleation pathway, but it proved capable of significantly extending the lifetime of the amorphous intermediate phase and thus delaying the transition to the final crystalline phase. Our observations confirm the notion that “non-classical” crystallization is a much more common phenomenon than initially believed – and that, for minerals forming in aqueous environments, it may actually be the rule rather than the exception.
KW - General Materials Science
KW - Building and Construction
PY - 2023
DO - https://doi.org/10.1016/j.cemconres.2023.107258
SN - 0008-8846
VL - 173
SP - 1
EP - 13
PB - Elsevier B.V.
AN - OPUS4-58162
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Karafiludis, Stephanos
A1 - Stawski, Tomasz
T1 - Crystallization study of transition metal phosphates: Characterization of a non-classical crystallization pathway
N2 - Industrial and agricultural waste streams (waste waters, sludges, tailings etc.), which contain high concentrations of NH4+, PO43- and transition metals, are environmentally harmful due to their toxic pollutants. At the same time, phosphorus and selective transition metals such as Cobalt could be potentially depleted as a critical raw material due to the high demand and rapidly declining natural ore deposits. Therefore, due to simultaneous scarcity and abundance, the phosphorus and 3d metal recovery from agricultural, industrial, mining, or urban wastewaters have been an important factor in sustaining our global consumption and preservation of the natural environment. Typically, separate pathways have been considered to extract hazardous substances such as transition metals or phosphate, independently from each other. Here, we investigate the crystallization of transition metal phosphate (TMP) compounds (NH4MPO4∙6H2O, M3(PO4)2∙8H2O with M = Ni2+, Co2+, NixCo1-x2+ M-struvite and M-phosphate octahydrate) out of aqueous solutions, which allow for P, ammonia and metal co-precipitation. The precipitation of these compounds from industrial and agricultural waste waters has high potential as a P- and 3d metal recovery route. For this purpose, a detailed understanding of the crystallization process beginning from combination of solved ions and ending in a final crystalline product is required. Through adjusting the reaction conditions, the stability, crystallite size and morphology of the as-obtained TMPs could be controlled. Detailed investigations of the precipitation process in time using ex- and in-situ techniques provided new insights into their non-classical crystallization mechanism/crystal engineering of these materials. These TMPs involve transitional colloidal nanophases during the crystallization process. Over time, their complex amorphous framework changes significantly resulting simultaneously in an agglomeration and densification of the compound. After extended reaction times these colloidal nanophases condensed to a final crystal. However, the reaction kinetics of the formation of a final crystalline product and the lifetime of these intermediate phases vary significantly depending on the metal cation involved in the precipitation process. Ni-struvite is stable in a wide reactant concentration range and at different metal/phosphorus (M/P)-ratios, whereas Co tends to form Co-struvite and/or Co-phosphate octahydrate depending on the (M/P)-ratio. The mixed NixCo1-x system shows a significantly different crystallization behavior and reaction kinetics of the precipitation compared to the pure endmembers. The observed various degree of stability could be linked to the octahedral metal coordination environment in these compounds. The achieved level of control over the precipitates, is highly desirable for 3d- and P-recovery methods. Under this paradigm, the crystals can be potentially upcycled as precursor materials for (electro)catalytical applications.
T2 - HZB Usermeeting 2023
CY - Berlin, Germany
DA - 22.06.2023
KW - Struvite
KW - Transition metal
KW - Phosphates
KW - Crystallization
KW - Amorphous phases
PY - 2023
AN - OPUS4-57775
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 - Matamoros-Veloza, A.
A1 - Stawski, Tomasz
A1 - Vargas, S.
A1 - Neville, A.
T1 - Study of a Local Structure at the Interface between Corrosion Films and Carbon Steel Surface in Undersaturated CO2 Environments
N2 - Industries transporting CO2 gas-saturated fluids have infrastructures made of carbon steel. This is a good material with great mechanical properties but prone to corrosion and potential failure. Corrosion in sweet environments involves the formation of FeCO3 as a corrosion film, which is recognized to play a protective role under certain conditions. This work on the dissolution of corrosion films in sweet environments, under acidic and undersaturated conditions, demonstrates that the effects on the integrity of steel are far more significant than the damage observed on the surface of the corrosion film. Our results prove that dissolution of FeCO3 involved the presence of an amorphous phase, the intermediate formation of FeCl2 or FeCl+, and the presence of a phase with short distance atom–atom correlations. The amorphous phase was identified as a mixture of retained γ-Fe and Fe3C. Partially broken α-Fe and Fe3C structures were identified to prove the damage on the material, confirming the interface zone without evident damage on the corrosion film. Dissolution affected both the α-Fe and FeCO3, with the lattice [102̅] from the FeCO3 crystalline structure being the fastest to dissolve. The damage of steel at the molecular scale was evident at the macroscale with pit depths of up to 250 μm. The impact on the integrity of steel can be, therefore, more drastic than frequently reported in industrial operations of CO2 transport industries that use cleaning procedures (e.g., acid treatment, pigging) as part of their operational activities.
KW - Steel
KW - Corrosion
KW - Siderite
KW - Diffraction
KW - Pair distribution function
KW - Synchrotron
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-572156
DO - https://doi.org/10.1021/acsomega.2c07631
SN - 2470-1343
VL - 8
IS - 9
SP - 8497
EP - 8504
PB - ACS
AN - OPUS4-57215
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Das, P.
A1 - Chakraborty, Gouri
A1 - Roeser, J.
A1 - Vogl, S.
A1 - Rabeah, J.
A1 - Thomas, A.
T1 - Integrating Bifunctionality and Chemical Stability in Covalent Organic Frameworks via One-Pot Multicomponent Reactions for Solar-Driven H2O2 Production
N2 - Multicomponent reactions (MCRs) can be used to introduce different functionalities into highly stable covalent organic frameworks (COFs). In this work, the irreversible three-component Doebner reaction is utilized to synthesize four chemically stable quinoline-4-carboxylic acid DMCR-COFs (DMCR-1−3 and DMCR-1NH) equipped with an acid−base bifunctionality. These DMCR-COFs show superior photocatalytic H2O2 evolution (one of the most important industrial oxidants) compared to the imine COF analogue (Imine-1). This is achieved with sacrificial oxidants but also in pure water and under an oxygen or air atmosphere. Furthermore, the DMCR-COFs show high photostability, durability, and recyclability. MCR-COFs thus provide a viable materials’ platform for solar to chemical energy conversion.
KW - Reactions
KW - Bifunctionality
KW - Postsynthetic modification
KW - Multicomponent
PY - 2022
DO - https://doi.org/10.1021/jacs.2c11454
SN - 0002-7863
VL - 145
IS - 5
SP - 2975
EP - 2984
PB - ACS Publications
AN - OPUS4-56922
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stolar, Tomislav
A1 - Pearce, Ben K.D.
A1 - Etter, Martin
A1 - Truong, Khai-Nghi
A1 - Ostojić, Tea
A1 - Krajnc, Andraž
A1 - Mali, Gregor
A1 - Rossi, Barbara
A1 - Molčanov, Krešimir
A1 - Lončarić, Ivor
A1 - Meštrović, Ernest
A1 - Užarević, Krunoslav
A1 - Grisanti, Luca
T1 - Base-pairing of uracil and 2,6-diaminopurine: from cocrystals to photoreactivity
N2 - We show that the non-canonical nucleobase 2,6-diaminopurine (D) spontaneously base pairs with uracil (U) in water and the solid state without the need to be attached to the ribose-phosphate backbone. Depending on the reaction conditions, D and U assemble in thermodynamically stable hydrated and anhydrated D-U base-paired cocrystals. Under UV irradiation, an aqueous solution of D-U base-pair undergoes photochemical degradation, while a pure aqueous solution of U does not. Our simulations suggest that D may trigger the U photodimerization and show that complementary base-pairing modifies the photochemical properties of nucleobases, which might have implications for prebiotic chemistry.
KW - Mechanochemistry
KW - In situ monitoring
KW - Cocrystals
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608622
DO - https://doi.org/10.1016/j.isci.2024.109894
VL - 27
IS - 6
SP - 1
EP - 14
PB - Elsevier Inc.
AN - OPUS4-60862
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Davison, Nathan
A1 - Hemingway, Jack M.
A1 - Wills, Corinne
A1 - Stolar, Tomislav
A1 - Waddell, Paul G.
A1 - Dixon, Casey M.
A1 - Barron, Luke
A1 - Dawson, James A.
A1 - Lu, Erli
T1 - Mechanochemical Synthesis of a Sodium Anion Complex [Na+(2,2,2-cryptand)Na–] and Studies of Its Reactivity: Two-Electron and One-Electron Reductions
N2 - Group 1 metal molecular chemistry is dominated by a +1 oxidation state, while a 0 oxidation state is widespread in the metals. A more exotic, yet still available, oxidation state of group 1 metal is −1, i.e., alkalide. Reported as early as the 1970s, the alkalides appear in every modern inorganic chemistry textbook as an iconic chemical curiosity, yet their reactivity remains unexplored. This is due to their synthetic hurdles. In this work, we report the first facile synthesis of the archetypical alkalide complex, [Na+(2,2,2-cryptand)Na–], which allows us to unveil a versatile reactivity profile of this once exotic species.
KW - Mechanochemistry
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608632
DO - https://doi.org/10.1021/acs.inorgchem.4c02914
VL - 63
IS - 32
SP - 15247
EP - 15258
PB - American Chemical Society (ACS)
AN - OPUS4-60863
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Alić, Jasna
A1 - Schlegel, Moritz-Caspar
A1 - Emmerling, Franziska
A1 - Stolar, Tomislav
T1 - Meeting the UN Sustainable Development Goals with Mechanochemistry
N2 - Chemistry traditionally relies on reactions in solution, but this method is increasingly problematic due to the scale of chemical processes and their economic and environmental impact. Handling residual chemical waste, including solvents, incurs significant costs and environmental pressure. Conversely, novel chemical approaches are needed to address pressing societal issues such as climate change, energy scarcity, food insecurity, and waste pollution. Mechanochemistry, a sustainable chemistry discipline that uses mechanical action to induce chemical reactivity without bulk solvents, is a hot topic in academic research on sustainable and green chemistry. Given its fundamentally different working principles from solution chemistry, mechanochemistry offers more efficient chemical processes and the opportunity to design new chemical reactions. Mechanochemistry has a profound impact on many urgent issues facing our society and it is now necessary to use mechanochemistry to address them. This Minireview aims to provide a guide for using mechanochemistry to meet the United Nations (UN) Sustainable Development Goals (SDGs), thereby contributing to a prosperous society. Detailed analysis shows that mechanochemistry connects with most UN SDGs and offers more cost‐efficiency than other approaches together with a superior environmental performance.
KW - Mechanochemistry
KW - SDGs
PY - 2024
DO - https://doi.org/10.1002/anie.202414745
SP - 1
EP - 3
PB - Wiley
AN - OPUS4-61108
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Sechi, R.
A1 - Fackeldey, K.
A1 - Chewle, Surahit
A1 - Weber, M.
T1 - SepFree NMF: A toolbox for analyzing the kinetics of sequential spectroscopic data
N2 - This work addresses the problem of determining the number of components from sequential spectroscopic data analyzed by non-negative matrix factorization without separability assumption (SepFree NMF). These data are stored in a matrix M of dimension “measured times” versus “measured wavenumbers” and can be decomposed to obtain the spectral fingerprints of the states and their evolution over time. SepFree NMF assumes a memoryless (Markovian) process to underline the dynamics and decomposes M so that M = WH, with W representing the components’ fingerprints and H their kinetics. However, the rank of this decomposition (i.e., the number of physical states in the process) has to be guessed from pre-existing knowledge on the observed process. We propose a measure for determining the number of components with the computation of the minimal memory effect resulting from the decomposition; by quantifying how much the obtained factorization is deviating from the Markovian property, we are able to score factorizations of a different number of components. In this way, we estimate the number of different entities which contribute to the observed system, and we can extract kinetic information without knowing the characteristic spectra of the single components. This manuscript provides the mathematical background as well as an analysis of computer generated and experimental sequentially measured Raman spectra.
KW - Kinetics from experiments
KW - Separability assumption
KW - Sequential spectroscopic data
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559046
DO - https://doi.org/10.3390/a15090297
SN - 1999-4893
VL - 15
IS - 9
SP - 1
EP - 16
PB - MDPI
CY - Basel
AN - OPUS4-55904
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Fackeldey, K.
A1 - Röhm, J.
A1 - Niknejad, A.
A1 - Chewle, Surahit
A1 - Weber, M.
T1 - Analyzing Raman spectral data without separabiliy assumption
N2 - Raman spectroscopy is a well established tool for the analysis of vibration spectra, which then allow for the determination of individual substances in a chemical sample, or for their phase transitions. In the time-resolved-Raman-sprectroscopy the vibration spectra of a chemical sample are recorded sequentially over a time interval, such that conclusions for intermediate products (transients) can be drawn within a chemical process. The observed data-matrix M from a Raman spectroscopy can be regarded as a matrix product of two unknown matrices W and H, where the first is representing the contribution of the spectra and the latter represents the chemical spectra. One approach for obtaining W and H is the non-negative matrix factorization. We propose a novel approach, which does not need the commonly used separability assumption. The performance of this approach is shown on a real world chemical example.
KW - Non-negative matrix factorization
KW - NMF
KW - Raman spectra
KW - Separability condition
KW - PCCA+
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559051
DO - https://doi.org/10.1007/s10910-020-01201-7
SN - 1572-8897
VL - 59
SP - 575
EP - 596
PB - Springer Science + Business Media
CY - Dordrecht
AN - OPUS4-55905
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Stawski, Tomasz
T1 - Particle-mediated origins of mesocrystalline disorder in calcium sulfate single crystals
N2 - Calcium sulfate minerals are abundant in natural and engineered environments and they exist in the form of three hydrates: gypsum (CaSO4·2H2O), bassanite (CaSO4·0.5H2O), and anhydrite (CaSO4). Due to their relevance in natural and industrial processes, the formation pathways of these calcium sulfate phases from aqueous solution have been the subject of intensive research1.
The state-of-the-art of the calcium sulfate formation mechanisms builds upon and goes beyond what we have come to appreciate in the astounding intricacy of other mineral formation processes from ions in aqueous solutions. The original, and rather naive, 'textbook' image of these phenomena, stemming from the adaptation of classical nucleation and growth theories, has increased in complexity due to the discovery of a variety of precursor and intermediate species2. These include solute clusters (e.g. prenucleation clusters, PNCs), liquid(-like) phases, as well as amorphous and nanocrystalline solids etc.. In this context, a number of studies have already revealed that nucleation in the CaSO4-H2O system is non-classical, where the formation of the different crystalline phases involves several steps including a common amorphous precursor1, 3, 4.
In this contribution we show that the formation of the amorphous phase involves the aggregation of small primary particles into larger disordered aggregates exhibiting a "brick-in-the-wall" structure5, 6. The actual crystallization occurs by the restructuring and coalescence of the particles ("bricks") into a given calcium sulfate phase depending on the physicochemical conditions of the solution. Importantly, the rearrangement process does not continue until a (nearly-)perfect homogeneous single crystal is obtained. Instead it comes to a stop, or at least significantly slows down. Such a process thus yields a final imperfect mesocrystal, composed of smaller domains rather than a continuous crystal structure, within which the domains are separated by an amorphous (i.e. less ordered) calcium sulfate phase.
Hence, the non-classical crystallization process of CaSO4 yields a final imperfect mesocrystal with an overall morphology resembling that of a single crystal, yet composed of smaller nano-domains. Importantly, these observations reveal that organic-free calcium sulfate mesocrystals grown by a particle mediated-pathway preserve in the final crystal structure a “memory” or “imprint” of their non-classical nucleation process, something that has been overlooked until now. Furthermore, the nano-scale misalignment of the structural sub-units within these crystals can propagate through the length-scales, and be expressed macroscopically as misaligned zones/domains in large single crystals (Fig. 1). Indeed, by considering large anhydrite crystals from the famous Naica Mine (“Cueva de los cristales”) we observed a suite of correlated self-similar void defects spanning multiple length-scales7 (Fig 2). These flaws, in the macroscopic crystal, stem from “seeds of imperfection” originating from a particle-mediated nucleation pathway. Hence, building a crystal could be viewed as Nature stacking blocks in a game of Tetris, whilst slowly forgetting the games core concept and failing to fill rows completely.
T2 - Granada Münster Discussion Meeting (GMDM)
CY - Granda, Spain
DA - 30.11.2022
KW - Anhydrite
KW - Mesocrystals
KW - Calcium sulfate
KW - Bassanite
KW - Gypsum
PY - 2022
AN - OPUS4-56476
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Stawski, Tomasz
T1 - Particle-mediated origins of mesocrystalline disorder in calcium sulfate single crystals
N2 - Calcium sulfate minerals are abundant in natural and engineered environments and they exist in the form of three hydrates: gypsum (CaSO4·2H2O), bassanite (CaSO4·0.5H2O), and anhydrite (CaSO4). Due to their relevance in natural and industrial processes, the formation pathways of these calcium sulfate phases from aqueous solution have been the subject of intensive research1.
The state-of-the-art of the calcium sulfate formation mechanisms builds upon and goes beyond what we have come to appreciate in the astounding intricacy of other mineral formation processes from ions in aqueous solutions. The original, and rather naive, 'textbook' image of these phenomena, stemming from the adaptation of classical nucleation and growth theories, has increased in complexity due to the discovery of a variety of precursor and intermediate species2. These include solute clusters (e.g. prenucleation clusters, PNCs), liquid(-like) phases, as well as amorphous and nanocrystalline solids etc.. In this context, a number of studies have already revealed that nucleation in the CaSO4-H2O system is non-classical, where the formation of the different crystalline phases involves several steps including a common amorphous precursor1, 3, 4.
In this contribution we show that the formation of the amorphous phase involves the aggregation of small primary particles into larger disordered aggregates exhibiting a "brick-in-the-wall" structure5, 6. The actual crystallization occurs by the restructuring and coalescence of the particles ("bricks") into a given calcium sulfate phase depending on the physicochemical conditions of the solution. Importantly, the rearrangement process does not continue until a (nearly-)perfect homogeneous single crystal is obtained. Instead it comes to a stop, or at least significantly slows down. Such a process thus yields a final imperfect mesocrystal, composed of smaller domains rather than a continuous crystal structure, within which the domains are separated by an amorphous (i.e. less ordered) calcium sulfate phase.
Hence, the non-classical crystallization process of CaSO4 yields a final imperfect mesocrystal with an overall morphology resembling that of a single crystal, yet composed of smaller nano-domains. Importantly, these observations reveal that organic-free calcium sulfate mesocrystals grown by a particle mediated-pathway preserve in the final crystal structure a “memory” or “imprint” of their non-classical nucleation process, something that has been overlooked until now. Furthermore, the nano-scale misalignment of the structural sub-units within these crystals can propagate through the length-scales, and be expressed macroscopically as misaligned zones/domains in large single crystals. Indeed, by considering large anhydrite crystals from the famous Naica Mine (“Cueva de los cristales”) we observed a suite of correlated self-similar void defects spanning multiple length-scales7. These flaws, in the macroscopic crystal, stem from “seeds of imperfection” originating from a particle-mediated nucleation pathway. Hence, building a crystal could be viewed as Nature stacking blocks in a game of Tetris, whilst slowly forgetting the games core concept and failing to fill rows completely.
T2 - ECCG: European Conference on Crystal Growth 7
CY - Paris, France
DA - 25.07.2022
KW - Anhydrite
KW - SAXS
KW - Single crystal
KW - Mesocrystal
PY - 2022
AN - OPUS4-56276
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Stawski, Tomasz
T1 - Particle-mediated origins of mesocrystallinity in calcium sulfate single crystals
N2 - Calcium sulfate minerals are abundant in natural and engineered environments in the form of three phases: gypsum (CaSO4·2H2O), bassanite (CaSO4·0.5H2O), and anhydrite (CaSO4). Due to their relevance in natural and industrial processes, the formation pathways of these phases from aqueous solution have been the subject of intensive research, a number of studies have already revealed that nucleation in the CaSO4-H2O system is non-classical, The formation of the different crystalline phases involves several steps including a common amorphous precursor.
In this contribution we show that the formation of the amorphous phase involves the aggregation of small primary particles into larger disordered aggregates exhibiting a "brick-in-the-wall" structure. The actual crystallization occurs by the restructuring and coalescence of the "bricks" into a given calcium sulfate phase depending on the physicochemical conditions of the solution. Such a process yields a final imperfect mesocrystal, composed of smaller domains rather than a continuous single crystal structure.
These observations reveal that organic-free calcium sulfate mesocrystals grown by a particle mediated-pathway might preserve in the final crystal structure an “imprint” of their growth pathways. Indeed, by considering large anhydrite crystals from the famous Naica Mine we observed a suite of correlated self-similar void defects spanning multiple length-scales. These flaws, in the macroscopic crystal, stem from “seeds of imperfection” originating from an original particle-mediated growth. Hence, building a crystal could be viewed as Nature stacking blocks in a game of Tetris, whilst slowly forgetting the games core concept and failing to fill rows completely.
T2 - GeoMinKöln 2022
CY - Cologne, Germany
DA - 11.09.2022
KW - Anhydrite
KW - Mesocrystals
KW - Calcium sulfate
PY - 2022
AN - OPUS4-56277
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kellermeier, Matthias
A1 - Scheck, Johanna
A1 - Drechsler, Markus
A1 - Rosenberg, Rose
A1 - Stawski, Tomasz
A1 - Fernandez-Martinez, Alejandro
A1 - Gebauer, Denis
A1 - Van Driessche, Alexander E. S.
T1 - From Ions to Crystals: A Comprehensive View of the Non‐Classical Nucleation of Calcium Sulfate
N2 - After years of intensive research and numerous important observations, our understanding of the early stages of crystallization is still limited due to the complexity of the underlying processes and their elusive character. In the present work, we provide a detailed view on the nucleation of calcium sulfate mineralization – an abundant mineral with broad use in construction industry – in aqueous systems at ambient conditions. As experimental basis, a co‐titration procedure with potentiometric, turbidimetric and conductometric detection was developed, allowing solution speciation and the formation of crystallization precursors to be monitored quantitatively as the level of nominal (super)saturation gradually increases. The nature and spatiotemporal evolution of these precursors was further elucidated by time‐resolved small‐angle X‐ray scattering (SAXS) and analytical ultracentrifugation (AUC) experiments, complemented by cryogenic transmission electron microscopy (cryo‐TEM) as a direct imaging technique. The results reveal how ions associate into nanometric primary species, which subsequently aggregate and develop anisotropic order by intrinsic structural reorganization. Our observations challenge the common understanding of fundamental notions such as the nucleation barrier or the meaning of supersaturation, with broad implications for mineralization phenomena in general and the formation of calcium sulfate in geochemical settings and industrial applications in particular.
KW - Calcium sulfate
KW - Gypsum
KW - Nucleation
KW - Crystallisation
PY - 2024
DO - https://doi.org/10.1002/anie.202408429
SP - 1
EP - 12
PB - Wiley
AN - OPUS4-61585
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Nag, Sayak
A1 - Emmerling, Franziska
A1 - Tothadi, Srinu
A1 - Bhattacharya, Biswajit
A1 - Ghosh, Soumyajit
T1 - Distinct photomechanical responses of two new 1,3-dimethylbarbituric acid derivative crystals
N2 - We demonstrate two distinct photomechanical responses (i.e. photomechanical bending and photosalient bursting) of two new 1,3-dimethylbarbituric acid derivative crystals based on tailoring their substituents and the modulation of their spacers.
KW - Crystal engineering
KW - Fexible crystals
PY - 2024
DO - https://doi.org/10.1039/D4CE00233D
SP - 1
EP - 12
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60141
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Dalgic, Mete-Sungur
T1 - Lösemittelfreie Probenpräparation zur Untersuchung von Polymerblends mittels MALDI-TOF MS
N2 - Die Probenpräparation ist ein wichtiger Schritt für die Qualität der Massenspektren in MALDI-TOF MS. Es werden Polymerproben, die lösungsmittelbasiert und lösungsmittelfrei präpariert worden sind, verglichen. Dabei werden die Intensitätsverhältnisse von ternären Mischungen von PEG-, PS- und PMMA-Polymeren beachtet.
T2 - 28. Kolloquium - Massenspektrometrische Techniken zur Untersuchung synthetischer Polymere
CY - Berlin, Germany
DA - 14.05.2024
KW - Polymere
KW - Massenspektrometrie
KW - Probenpräparation
PY - 2024
AN - OPUS4-60032
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Dalgic, Mete-Sungur
T1 - Discrimination effects in MALDI-MS of Ternary Polymer Mixtures
N2 - MALDI-TOF MS is a viable method to determine molecular weights of polymers. However, quantification using MALDI-TOF MS presents specific challenges due to intensity biases caused by instrumental and sample-specific parameters. In this presentation, the influence of molar masses on MALDI-TOF mass spectra is explored. The intensities of a ternary PMMA blend with different mixture ratios are depicted in contour plots.
T2 - SALSA Make and Measure 2022
CY - Berlin, Germany
DA - 15.09.2022
KW - MALDI-TOF MS
KW - Ternary polymer blends
KW - PMMA
PY - 2022
AN - OPUS4-62212
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -