TY - JOUR A1 - Das, Chayanika A1 - Kastania, Eleni A1 - Witt, Julia A1 - Özcan Sandikcioglu, Özlem T1 - Corrosion protection properties of poly(4-vinyl pyridine) containing multilayer polymeric coatings on magnesium alloy AZ31 JF - Materials and Corrosion N2 - The aim of this study is to develop polymeric thin films for corrosion protection of magnesium alloy AZ31. As polymer matrix, poly(4-vinyl pyridine) (P4VP) is selected due to its semiconducting properties and protonic conductivity. Polyacrylic acid is tested as crosslinking layers to improve interfacial adhesion. The macroscopic corrosion properties of the multilayer coatings are investigated by means of electrochemical methods, such as linear sweep voltammetry and electrochemical impedance spectroscopy (EIS), in corrosive media simulating technical and biomedical applications. It is demonstrated that thin multilayer coatings can suppress the corrosion rates of magnesium alloys. To our best knowledge, this is the first demonstration of the use of P4VP as a conducting polymer film with protonic conductivity for corrosion protection of magnesium alloys. KW - Multilayercoatings KW - AZ31 KW - Corrosion protection KW - Intrinsically conducting polymers KW - Magnesium alloys PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551799 DO - https://doi.org/10.1002/maco.202112708 SN - 0947-5117 VL - 73 IS - 3 SP - 427 EP - 435 PB - Wiley VHC-Verlag AN - OPUS4-55179 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] JF - Research Paper 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 - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Malpass-Evans, R. A1 - McKeown, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Low frequency vibrations and diffusion in disordered polymers bearing an intrinsic microporosity as revealed by neutron scattering JF - Crystals N2 - The microscopic diffusion and the low frequency density of states (VDOS) of PIM-EATB(CH3) are investigated by inelastic and quasi-elastic neutron scattering where also the demethylated counterpart of PIM-EA-TB(H2) is considered. These intrinsic microporous polymers are characterized by large BET surface area values of several hundred m2/g and pore sizes between 0.5 and 2 nm. Detailed comparison is made to the archetype of polymers of intrinsic microporosity, PIM-1, and polynorbornenes also bearing a microporosity. Due to the wavelength of neutrons, the diffusion and vibrations can be addressed on microscopic length and time scales. From the inelastic neutron scattering experiments the low frequency density of states (VDOS) is estimated which shows excess contributions to the Debye-type VDOS known as Boson peak. It was found that the maximum frequency of the Boson peak decreases with increasing microporosity characterized by the BET surface area. However, besides the BET surface area, additional factors such as the backbone stiffness govern the maximum frequency of the Boson peak. Further the mean squared displacement related to microscopic motions was estimated from elastic fixed window scans. At temperatures above 175 K, the mean squared displacement PIM-EA-TB(CH3) is higher than that for the demethylated counterpart PIM-EA-TB(H2). The additional contribution found for PIM-EATB(CH3) is ascribed to the rotation of the methyl group in this polymer because the only difference between the two structures is that PIM-EA-TB(CH3) has methyl groups where PIM-EA-TB(H2) has none. A detailed comparison of the molecular dynamics is also made to that of PIM-1 and the microporous polynorbornene PTCNSi1. The manuscript focuses on the importance of vibrations and the localized molecular mobility characterized by the microscopic diffusion on the gas Transport in polymeric separation membranes. In the frame of the random gate model localized fluctuations can open or close bottlenecks between pores to enable the diffusion of gas molecules. KW - Polymer of intrisic microporosity KW - Neutron scattering KW - Boson peak KW - Methyl group rotation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538490 DO - https://doi.org/10.3390/cryst11121482 VL - 11 IS - 12 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-53849 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Musl, O. A1 - Sulaeva, I. A1 - Sumerskii, I. A1 - Mahler, A.K. A1 - Rosenau, T. A1 - Falkenhagen, Jana A1 - Potthast, A. T1 - Mapping of the Hydrophobic Composition of Lignosulfonates JF - ACS Sustainable Chemistry&Engineering N2 - Lignosulfonates are industrial biorefinery products that are characterized by significant variability and heterogeneity in their structural composition. Typically, they exhibit high dispersities in molar mass (molar mass distribution-MMD) and in functionalities (functionality-type distribution - FTD), which crucially affect their material usage. In terms of FTD, state-of-the-art Lignin analytics still rely mainly on the determination of functional group contents, which are statistical averages with limited explanatory power. In contrast, our online hydrophobic interaction chromatography−size-exclusion chromatography 2D-LC approach combines the determination of both MMD and FTD in a single measurement to provide a comprehensive picture of the characteristic composition of industrial lignosulfonates information hitherto inaccessible by state-of-the-art lignin analytics. In this way, the complex inter - relationships between these two important structural parameters can be studied in an unprecedented manner. In this study, we reveal the considerable differences in terms of hydrophobic composition and its dispersity present in a range of different industrial lignosulfonates - data desperately needed in tailoring and refining of lignosulfonate composition for material usage. KW - Lignosulfonates KW - Amphiphilicity KW - Hydrophobic interaction chromatography KW - Two-dimensional chromatography (2D-LC) KW - Charge-to-size-ratio PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538612 DO - https://doi.org/10.1021/acssuschemeng.1c06469 VL - 9 IS - 49 SP - 16786 EP - 16795 PB - ASC Publications AN - OPUS4-53861 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emmerling, Franziska A1 - Martins, Ines T1 - Carbamazepine Dihydroxybenzoic Acid Cocrystals: Exploring Packing Interactions and Reaction Kinetics JF - Crystal Growth and Design N2 - Herein, we present the mechanochemical formation of three new cocrystals containing the active pharmaceutical ingredient carbamazepine and dihydroxybenzoic acids as coformers (CBZ:2,4-DHBA 1:1, CBZ:2,5-DHBA 1:1, and CBZ:2,6-DHBA 1:1). Rietveld methods were used for three different purposes: (i) refining all structures solved using powder X-ray diffraction, (ii) performing a quantitative phase analysis of the diffraction data collected from ex situ mechanochemical reactions at different milling times, and (iii) determining the cocrystallization kinetic profiles. The rate of cocrystallization was found to be higher for the formation of CBZ:2,4-DHBA and CBZ:2,6-DHBA, reaching an equilibrium after 600 s of milling. In the case of CBZ:2,5-DHBA a short induction period of 20 s was detected prior to the start of the reaction and an equilibrium was reached after 1200 s. An empirical trend between the rate of cocrystallization and the structural complexity of the cocrystal product was found. The slowest cocrystallization rate observed for CBZ:2,5-DHBA corresponds to the crystal structure deviating substantially from the hydrogen-bonding motif found in the reactants. KW - Mechanochemistry KW - In situ real-time monitoring KW - Kinetics PY - 2021 DO - https://doi.org/10.1021/acs.cgd.1c00902 VL - 21 IS - 12 SP - 6961 EP - 6970 PB - ACS Publications AN - OPUS4-54407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Crouzier, L. A1 - Feltin, N. A1 - Delvallée, A. A1 - Pellegrino, Francesco A1 - Maurino, V. A1 - Cios, Grzegorz A1 - Tokarski, T. A1 - Salzmann, Christoph A1 - Deumer, J. A1 - Gollwitzer, C. A1 - Hodoroaba, Vasile-Dan T1 - Correlative analysis of the dimensional properties of bipyramidal titania nanoparticles by complementing electron microscopy with other methods JF - Nanomaterials N2 - In this paper, the accurate determination of the size and size distribution of bipyramidal anatase nanoparticles (NPs) after deposition as single particles on a silicon substrate by correlative Scanning Electron Microscopy (SEM) with Atomic Force Microscopy (AFM) analysis is described as a new measurement procedure for metrological purposes. The knowledge of the exact orientation of the NPs is a crucial step in extracting the real 3D dimensions of the particles. Two approaches are proposed to determine the geometrical orientation of individual nano‐bipyramides: (i) AFM profiling along the long bipyramid axis and (ii) stage tilting followed by SEM imaging. Furthermore, a recently developed method, Transmission Kikuchi Diffraction (TKD), which needs preparation of the crystalline NPs on electron‐transparent substrates such as TEM grids, has been tested with respect to its capability of identifying the geometrical orientation of the individual NPs. With the NPs prepared homogeneously on a TEM grid, the transmission mode in a SEM, i.e., STEM‐in‐SEM (or T‐SEM), can be also applied to extract accurate projection dimensions of the nanoparticles from the same sample area as that analysed by SEM, TKD and possibly AFM. Finally, Small Angle X‐ray Scattering (SAXS) can be used as an ensemble technique able to measure the NPs in liquid suspension and, with ab‐initio knowledge of the NP shape from the descriptive imaging techniques, to provide traceable NP size distribution and particle concentration. KW - Nanoparticles KW - Complex-shape KW - Bipyramid KW - Electron microscopy KW - AFM KW - Size measurements KW - TKD KW - STEM-in-SEM KW - SAXS KW - Nanoparticle concentration KW - Correlative analysis PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539888 DO - https://doi.org/10.3390/nano11123359 SN - 2079-4991 VL - 11 IS - 12 SP - 1 EP - 19 PB - MDPI CY - Basel AN - OPUS4-53988 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stawski, Tomasz A1 - Smales, Glen Jacob A1 - Scoppola, E. A1 - Jha, D. A1 - Morales, L. F. G. A1 - Moya, A. A1 - Wirth, R. A1 - Pauw, Brian Richard A1 - Emmerling, Franziska A1 - Van Driessche, A. E. S. T1 - Seeds of imperfection rule the mesocrystalline disorder in natural anhydrite single crystals JF - Proceedings of the National Academy of Sciences of the United States of America (PNAS) N2 - In recent years, we have come to appreciate the astounding intricacies associated with the formation of minerals from ions in aqueous solutions. In this context, a number of studies have revealed that the nucleation of calcium sulfate systems occurs nonclassically, involving the aggregation and reorganization of nanosized prenucleation species. In recent work, we have shown that this particle-mediated nucleation pathway is actually imprinted in the resultant micrometer-sized CaSO4 crystals. This property of CaSO4 minerals provides us with the unique opportunity to search for evidence of nonclassical nucleation pathways in geological environments. In particular, we focused on large anhydrite Crystals extracted from the Naica Mine in Mexico. We were able to shed light on this mineral's growth history by mapping defects at different length scales. Based on this, we argue that the nanoscale misalignment of the structural subunits, observed in the initial calcium sulfate crystal seeds, propagates through different length scales both in morphological, as well as in strictly crystallographic aspects, eventually causing the formation of large mesostructured single crystals of anhydrite. Hence, the nonclassical nucleation mechanism introduces a “seed of imperfection,” which leads to a macroscopic “single” crystal whose fragments do not fit together at different length scales in a self-similar manner. Consequently, anisotropic voids of various sizes are formed with very welldefined walls/edges. However, at the same time, the material retains in part its single crystal nature. KW - Calcium sulfate KW - Anhydrite KW - Mesocrystal KW - Nucleation KW - Naica PY - 2021 DO - https://doi.org/10.1073/pnas.2111213118 SN - 0027-8424 VL - 118 IS - 48 SP - 1 EP - 11 PB - National Academy of Sciences (USA) CY - Washington AN - OPUS4-53820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Gräf, S. T1 - Ten Open Questions about Laser-Induced Periodic Surface Structures JF - Nanomaterials N2 - Laser-induced periodic surface structures (LIPSS) are a simple and robust route for the nanostructuring of solids that can create various surface functionalities featuring applications in optics, medicine, tribology, energy technologies, etc. While the current laser technologies already allow surface processing rates at the level of m2/min, industrial applications of LIPSS are sometimes hampered by the complex interplay between the nanoscale surface topography and the specific surface chemistry, as well as by limitations in controlling the processing of LIPSS and in the long-term stability of the created surface functions. This Perspective article aims to identify some open questions about LIPSS, discusses the pending technological limitations, and sketches the current state of theoretical modelling. Hereby, we intend to stimulate further research and developments in the field of LIPSS for overcoming these limitations and for supporting the transfer of the LIPSS technology into industry. KW - Laser-induced periodic surface structures (LIPSS) KW - Industrial application KW - Functional properties KW - Surface functionalization KW - Modelling PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539503 DO - https://doi.org/10.3390/nano11123326 SN - 2079-4991 VL - 11 IS - 12 SP - 1 EP - 21 PB - MDPI CY - Basel, Switzerland AN - OPUS4-53950 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 JF - Journal of Applied Physics 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 - Sachse, René A1 - Moor, Maëlle A1 - Kraehnert, Ralph A1 - Hodoroaba, Vasile-Dan A1 - Hertwig, Andreas T1 - Ellipsometry-based approach for the characterization of mesoporous thin films for H2 technologies JF - Advanced Engineering Materials N2 - Porous thin layer materials are gaining importance in different fields of technology and pose a challenge to the accurate determination of materials properties important for their function. In this work, we demonstrate a hybrid measurement technique using ellipsometry together with other independent methods for validation. Ellipsometry provides information about the porosity of different mesoporous films (PtRuNP/OMC = 45%; IrOx = 46%) as well as about the pore size (pore radius of ca. 5 nm for PtRuNP/OMC). In addition, the electronic structure of a material, such as intraband transitions of a mesoporous IrOx film, can be identified, which can be used to better understand the mechanisms of chemical processes. In addition, we show that ellipsometry can be used as a scalable imaging and visualization method for quality assurance in production. These require accurate and traceable measurements, with reference materials playing an important role that include porosity and other related properties. We show that our novel analytical methods are useful for improving analytical work in this entire field. KW - Porous materials KW - Electrolysis KW - Spectroscopic ellipsometry KW - Hybrid metrology measurement KW - Electron microscopy PY - 2021 DO - https://doi.org/10.1002/adem.202101320 SP - 1 EP - 17 PB - Wiley-VCH AN - OPUS4-53960 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -