TY - JOUR A1 - Almalla, A. A1 - Özcan Sandikcioglu, Özlem A1 - Witt, Julia T1 - In Situ Atomic Force Microscopy Analysis of the Corrosion Processes at the Buried Interface of an Epoxy-like Model Organic Film and AA2024-T3 Aluminum Alloy N2 - The application of characterization methods with high spatial resolution to the analysis of buried coating/metal interfaces requires the design and use of model systems. Herein, an epoxy-like thin film is used as a model coating resembling the epoxy-based coatings and adhesives widely used in technical applications. Spin coating is used for the deposition of a 30 nm-thin bilayer (BL) composed of poly-(ethylenimine) (PEI) and poly[(o-cresyl glycidyl ether)-co-formaldehyde] (CNER). Fourier-transform infrared spectroscopy (FTIR) results confirm that the exposure of coated AA2024-T3 (AA) samples to the corrosive electrolyte solution does not cause the degradation of the polymer layer. In situ atomic force microscopy (AFM) studies are performed to monitor local corrosion processes at the buried interface of the epoxy-like film and the AA2024-T3 aluminum alloy surface in an aqueous electrolyte solution. Hydrogen evolution due to the reduction of water as the cathodic corrosion reaction leads to local blister formation. Based on the results of the complementary energy-dispersive X-ray spectroscopy (EDX) analysis performed at the same region of interest, most of the hydrogen evolved originates at the vicinity of Mg-containing intermetallic particles. KW - Scanning Kelvin probe force microscopy KW - Aluminum alloys KW - Buried interfaces KW - In situ atomic force microscopy KW - Local corrosion PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546932 DO - https://doi.org/10.1002/adem.202101342 SN - 1438-1656 SP - 1 EP - 9 PB - Wiley VHC-Verlag AN - OPUS4-54693 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sözen, H.I. A1 - Mendive-Tapia, E. A1 - Hickel, Tilmann A1 - Neugebauer, J. T1 - Ab initio investigations of point and complex defect structures in B2-FeAl N2 - We study single-site and two-site defect structures in B2-type Fe-Al alloys by means of density functional theory supercell calculations. The defect formation energies are calculated as functions of the chemical potential, which are used to obtain the dependence of the defect concentrations on Al content at different temperatures. We also examine the converging behavior of the formation energies with respect to the supercell size to study the corresponding limit of dilute defects. The effect of magnetism is investigated by considering nonmagnetic, ferromagnetic, and paramagnetic states, calculations for the latter showing that the magnitude of the local magnetic moments strongly impacts the defect formation energies. The methodological studies are used to provide explanations for the wide spread of defect formation energies reported by experiments and other theoretical investigations. Based on these insights, the stability of the B2-FeAl structure as a function of Al concentration is obtained and discussed. KW - Atomistic models KW - Defects KW - Thermodynamics PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546956 DO - https://doi.org/10.1103/PhysRevMaterials.6.023603 SN - 2475-9953 VL - 6 IS - 2 SP - 1 EP - 11 PB - APS CY - College Park, MD AN - OPUS4-54695 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 A1 - Karapanagiotis, Christos A1 - Hicke, Konstantin A1 - Wosniok, Aleksander A1 - Krebber, Katerina T1 - Distributed humidity fiber-optic sensor based on BOFDA using a simple machine learning approach N2 - We report, to our knowledge for the first time, on distributed relative humidity sensing in silica polyimide-coated optical fibers using Brillouin optical frequency domain analysis (BOFDA). Linear regression, which is a simple and well-interpretable algorithm in machine learning and statistics, is utilized. The algorithm is trained using as features the Brillouin frequency shifts and linewidths of the fiber’s multipeak Brillouin spectrum. To assess and improve the effectiveness of the regression algorithm, we make use of machine learning concepts to estimate the model’s uncertainties and select the features that contribute most to the model’s performance. In addition to relative humidity, the model is also able to simultaneously provide distributed temperature information addressing the well-known cross-sensitivity effects. KW - Fiber optics sensors KW - Machine learning KW - Brillouin distributed sensing KW - Humidity sensing KW - Simultaneous temperature and humidity sensing PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546294 DO - https://doi.org/10.1364/OE.453906 VL - 30 IS - 8 SP - 12484 EP - 12494 PB - OPTICA AN - OPUS4-54629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Cui A1 - Kitzmann, W.R. A1 - Weigert, Florian A1 - Förster, Ch. A1 - Wang, X. A1 - Heintze, K. A1 - Resch-Genger, Ute T1 - Matrix Effects on Photoluminescence and Oxygen Sensitivity of a Molecular Ruby N2 - The molecular ruby analogue [Cr(ddpd)2]3+ (ddpd=N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine) exhibits near infrared (NIR) emission with a high photoluminescence (PL) quantum yield ΦPL of 11 % and a lifetime of 898 μs in deaerated water at room temperature. While ligand-based control of the photophysical properties has received much attention, influences of the counter anions and microenvironment are still underexplored. In this study, the luminescence properties of the molecular ruby were systematically examined for the counter anions Cl−, Br−, [BF4]−, [PF6]−, [BPh4]−, and [BArF24]− in acetonitrile (MeCN) solution, in crystals, and embedded into polystyrene nanoparticles (PSNP). Stern-Volmer analyses of the oxygen quenching studies in the intensity and lifetime domain showed the highest oxygen sensitivity of the complexes with the counter anions of [BF4]− and [BArF24]−, which also revealed the longest luminescence lifetimes. Embedding [Cr(ddpd)2][PF6]3 in PSNPs and shielding with poly(vinyl alcohol) yields a strongly NIR-emissive oxygen-insensitive material with a record ΦPL of 15.2 % under ambient conditions. KW - Fluorescence KW - Sensor KW - Oxygen KW - Quantum yield KW - Quality assurance KW - Complex KW - Cr(III) KW - Lifetime KW - Ligand KW - Solid state KW - X-Ray analysis KW - Structure-property relationship KW - Nano KW - Polymer KW - Particle PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546057 DO - https://doi.org/10.1002/cptc.202100296 SN - 2367-0932 VL - 6 IS - 6 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54605 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 - Martins, Ines A1 - Al-Sabbagh, Dominik A1 - Bentrup, U. A1 - Marquardt, Julien A1 - Schmid, Thomas A1 - Scoppola, E. A1 - Kraus, Werner A1 - Stawski, Tomasz A1 - de Oliveira Guilherme Buzanich, Ana A1 - Yusenko, Kirill A1 - Weidner, Steffen A1 - Emmerling, Franziska T1 - Formation Mechanism of a Nano-Ring of Bismuth Cations and Mono-Lacunary Keggin-Type Phosphomolybdate N2 - A new hetero-bimetallic polyoxometalate (POM) nano-ring was synthesized in a one-pot procedure. The structure consists of tetrameric units containing four bismuth-substituted monolacunary Keggin anions including distorted [BiO8] cubes. The nano-ring is formed via self-assembly from metal precursors in aqueous acidic medium. The compound (NH4)16[(BiPMo11O39)4] ⋅ 22 H2O; (P4Bi4Mo44) was characterized by single-crystal X-ray diffraction, extended X-ray absorption fine structure spectroscopy (EXAFS), Raman spectroscopy, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF), and thermogravimetry/differential scanning calorimetry mass spectrometry (TG-DSC-MS). The formation of the nano-ring in solution was studied by time-resolved in situ small- and wide-angle X-ray scattering (SAXS/WAXS) and in situ EXAFS measurements at the Mo−K and the Bi−L3 edge indicating a two-step process consisting of condensation of Mo-anions and formation of Bi−Mo-units followed by a rapid self-assembly to yield the final tetrameric ring structure. KW - Bismuth KW - In situ EXAFS KW - In situ SAXS/WAXS KW - Lacunary Keggin ion KW - Polyoxometalates KW - Self-assembly PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546823 DO - https://doi.org/10.1002/chem.202200079 SN - 0947-6539 VL - 28 IS - 27 SP - 1 EP - 7 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gugin, Nikita A1 - Villajos Collado, José Antonio A1 - Feldmann, Ines A1 - Emmerling, Franziska T1 - Mix and wait – a relaxed way for synthesizing ZIF-8 N2 - Herein we report the synthesis of a zeolitic imidazolate framework (ZIF-8) by an easy “mix and wait” procedure. In a closed vial, without any interference, the mixture of 2-methylimidazole and basic zinc carbonate assembles into the crystalline product with approx. 90% conversion after 70 h. The reaction exhibits sigmoidal kinetics due to the self-generated water which accelerates the reaction. KW - In-situ analysis KW - Mechanochemistry KW - MOF KW - Synthesis KW - ZIF-8 PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546841 DO - https://doi.org/10.1039/D2RA00740A VL - 12 SP - 8940 EP - 8944 PB - Royal Society of Chemistry AN - OPUS4-54684 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Nietzke, Jonathan A1 - Mente, Tobias A1 - Richter, Tim A1 - Kannengießer, Thomas T1 - Characterization of Hydrogen Diffusion in Offshore Steel S420G2+M Multi-layer Submerged Arc Welded Joint N2 - As onshore installation capacity is limited, the increase in the number of offshore wind turbines (OWT) is a major goal. In that connection, the OWTs continuously increase in size and weight and demand adequate foundations concepts like monopiles or tripods. These components are typically manufactured from welded mild steel plates with thickness up to 200 mm. The predominant welding technique is submerged arc welding (SAW). In accordance with the standards, the occurrence of hydrogen-assisted cracking is anticipated by either a minimum waiting time (MWT, before non-destructive testing of the welded joint is allowed) at ambient or a hydrogen removal heat treatment (HRHT) at elevated temperatures. The effectiveness of both can be estimated by calculation of the diffusion time, i.e., diffusion coefficients. In this study, these coefficients are obtained for the first time for a thick-walled S420G2+M offshore steel grade and its multi-layer SAW joint. The electrochemical permeation technique at ambient temperature is used for the determination of diffusion coefficients for both the base material and the weld metal. The coefficients are within a range of 1025 to 1024 mm2/s (whereas the weld metal had the lowest) and are used for an analytical and numerical calculation of the hydrogen diffusion and the related MWT. The results showed that long MWT can occur, which would be necessary to significantly decrease the hydrogen concentration. Weld metal diffusion coefficients at elevated temperatures were calculated from hydrogen desorption experiments by carrier gas hot extraction. They are within a range of 1023 mm2/s and used for the characterization of a HRHT dwell-time. The analytical calculation shows the same tendency of long necessary times also at elevated temperatures. That means the necessary time is strongly influenced by the considered plate thickness and the estimation of any MWT/HRHT via diffusion coefficients should be critically discussed. T2 - European Congress and Exhibition on Advanced Materials and Process - Euromat 2021 CY - Online meeting DA - 13.09.2021 KW - Thick-walled KW - Hydrogen diffusion KW - Offshore KW - Steel KW - Submerged arc welding PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544127 DO - https://doi.org/10.1007/s11665-022-06679-7 SN - 1059-9495 SP - 1 EP - 13 PB - Springer Nature AN - OPUS4-54412 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raniro, H.R. A1 - Soares, T.de M. A1 - Adam, Christian A1 - Pavinato, P.S. T1 - Waste-derived fertilizers can increase phosphorus uptake by sugarcane and availability in a tropical soil N2 - The use of highly water-soluble phosphorus (P) fertilizers can lead to P fixation in the soil, reducing fertilization efficiency. Waste-derived, low water-solubility sources can potentially increase sugarcane’s P uptake compared to triple superphosphate by reducing adsorption to the soil. Aims:We aimed to test struvite, hazenite, and AshDec® for their agronomic potential as recycled fertilizers for sugarcane production in a typical tropical soil.We hypothesize that these sources can reduce P fixation in the soil, increasing its availability and sugarcane’s absorption. Methods: In a greenhouse pot experiment, two consecutive sugarcane cycles, 90 days each, were conducted in a Ferralsol. The recovered sources struvite, hazenite, AshDec®, and the conventional triple superphosphate were mixed in the soil in three P doses (30, 60, and 90 mg kg–1), aside a control (nil-P). At both harvests, sugarcane number of sprouts, plant height, stem diameter, dry mass yield, shoot phosphorus, and soil P fractionation were investigated. Results: At 90 days, struvite and hazenite performed better for dry mass yield (70.7 and 68.3 g pot–1, respectively) than AshDec® and triple superphosphate (59.8 and 57.4 g pot–1, respectively) and for shoot P, with 98.1, 91.6, 75.6, and 66.3 mg pot–1, respectively. At 180 days, struvite outperformed all treatments for dry mass yield (95.3 g pot–1) and AshDec® (75.5 mg pot–1) for shoot P. Struvite was 38% and hazenite 21% more efficient than triple superphosphate in P uptake, while AshDec® was 6% less efficient. Soil had higher labile P under struvite, hazenite, and AshDec® than triple superphosphate by the end of the first cycle, while only the later increased nonlabile P by the end of the experiment (180 days). Conclusions:Waste-derived P sources were more efficient in supplying P for sugarcane and delivering labile P in 180 days than triple superphosphate. KW - AshDec KW - Hazenite KW - P-efficiency KW - Recycled sources KW - Struvite PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544216 DO - https://doi.org/10.1002/jpln.202100410 SN - 1436-8730 SP - 1 EP - 12 PB - Wiley-VCH GmbH AN - OPUS4-54421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -