TY - JOUR
A1 - Emmerling, Franziska
A1 - Stock, Norbert
A1 - Tadei, Marco
A1 - Demel, Jan
A1 - Cabeza, Aurelio
A1 - Viviani, Riccardo
A1 - Demadis, Konstantinos
A1 - Vassaki, Maria
T1 - New directions in metal phosphonate and phosphinate chemistry
N2 - In September 2018, the First European Workshop on Metal Phosphonates Chemistry brought together some prominent researchers in the field of metal phosphonates and phosphinates with the aim of discussing past and current research efforts and identifying future directions. The scope of this perspective article is to provide a critical overview of the topics discussed during the workshop, which are divided into two main areas: synthesis and characterisation, and applications. In terms of synthetic methods, there has been a push towards cleaner and more efficient approaches. This has led to the introduction of high-throughput synthesis and mechanochemical synthesis. The recent success of metal–organic frameworks has also promoted renewed interest in the synthesis of porous metal phosphonates and phosphinates. Regarding characterisation, the main advances are the development of electron diffraction as a tool for crystal structure determination and the deployment of in situ characterisation techniques, which have allowed for a better understanding of reaction pathways. In terms of applications, metal phosphonates have been found to be suitable materials for several purposes: they have been employed as heterogeneous catalysts for the synthesis of fine chemicals, as solid sorbents for gas separation, notably CO2 capture, as materials for electrochemical devices, such as fuel cells and rechargeable batteries, and as matrices for drug delivery.
KW - Metal phosphonates
KW - Metal–organic frameworks
KW - X-ray and electron diffraction
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-484346
DO - https://doi.org/10.3390/cryst9050270
SN - 2073-4352
VL - 9
IS - 5
SP - 270, 1
EP - 36
PB - MDPI
AN - OPUS4-48434
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Legall, Herbert
A1 - Schwanke, Christoph
A1 - Bonse, Jörn
A1 - Krüger, Jörg
T1 - The influence of processing parameters on X‑ray emission during ultra‑short pulse laser machining
N2 - During ultra-short laser material processing at high laser pulse repetition rates unwanted X-ray radiation can be generated in a quantity that may constitute a potential risk for health. An adequate X-ray radiation protection requires a thoroughly understanding of the influence of the laser processing parameters on the generation of X-ray radiation. In the present work, the generated X-ray dose during laser machining was investigated in air for varying beam scanning conditions at a pulse duration of 925 fs, a center wavelength of 1030 nm and a laser peak intensity of 2.6 × 10^14 W/cm^2. The X-ray radiation dose and the corresponding spectral X-ray emission were investigated in dependence on the laser’s pulse repetition rate and on the beam scanning speed. The results show a strong dependence of the X-ray emission on these laser processing parameters.
KW - Laser-induced X-ray emission
KW - Ultrashort laser material interaction
KW - Femtosecond laser
KW - Radiation protection
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486441
DO - https://doi.org/10.1007/s00339-019-2827-y
SN - 0947-8396
SN - 1432-0630
VL - 125
IS - 8
SP - 570, 1
EP - 8
PB - Springer
AN - OPUS4-48644
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Topolniak, Ievgeniia
A1 - Hodoroaba, Vasile-Dan
A1 - Pfeifer, Dietmar
A1 - Braun, Ulrike
A1 - Sturm, Heinz
T1 - Boehmite Nanofillers in Epoxy Oligosiloxane Resins: Influencing the Curing Process by Complex Physical and Chemical Interactions
N2 - In this work, a novel boehmite (BA)-embedded organic/inorganic nanocomposite coating based on cycloaliphatic epoxy oligosiloxane (CEOS) resin was fabricated applying UV-induced cationic polymerization. The main changes of the material behavior caused by the nanofiller were investigated with regard to its photocuring kinetics, thermal stability, and glass transition. The role of the particle surface was of particular interest, thus, unmodified nanoparticles (HP14) and particles modified with p-toluenesulfonic acid (OS1) were incorporated into a CEOS matrix in the concentration range of 1–10 wt.%. Resulting nanocomposites exhibited improved thermal properties, with the glass transition temperature (Tg) being shifted from 30 °C for unfilled CEOS to 54 °C (2 wt.% HP14) and 73 °C (2 wt.% OS1) for filled CEOS. Additionally, TGA analysis showed increased thermal stability of samples filled with nanoparticles. An attractive interaction between boehmite and CEOS matrix influenced the curing. Real-time infrared spectroscopy (RT-IR) experiments demonstrated that the epoxide conversion rate of nanocomposites was slightly increased compared to neat resin. The beneficial role of the BA can be explained by the participation of hydroxyl groups at the particle surface in photopolymerization processes and by the complementary contribution of p-toluenesulfonic acid surface modifier and water molecules introduced into the system with nanoparticles.
KW - Real-time infrared spectroscopy
KW - Boehmite
KW - Nanocomposite
KW - Cationic photocuring
KW - Cycloaliphatic epoxy oligosiloxane
KW - Epoxy conversion degree
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-479628
DO - https://doi.org/10.3390/ma12091513
VL - 12
IS - 9
SP - 1513
PB - MDPI
AN - OPUS4-47962
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ringleb, F.
A1 - Andree, Stefan
A1 - Heidmann, B.
A1 - Bonse, Jörn
A1 - Eylers, K.
A1 - Ernst, O.
A1 - Boeck, T.
A1 - Schmid, M.
A1 - Krüger, Jörg
T1 - Femtosecond laser-assisted fabrication of chalcopyrite micro-concentrator photovoltaics
N2 - Micro-concentrator solar cells offer an attractive way to further enhance the efficiency of planar-cell technologies while saving absorber material. Here, two laser-based bottom-up processes for the fabrication of regular arrays of CuInSe2 and Cu(In,Ga)Se2 microabsorber islands are presented, namely one approach based on nucleation and one based on laser-induced forward transfer.
Additionally, a procedure for processing these microabsorbers to functioning micro solar cells connected in parallel is demonstrated. The resulting cells show up to 2.9% efficiency and a significant efficiency enhancement under concentrated Illumination.
KW - Chalcopyrite
KW - Femtosecond laser patterning
KW - Laser-induced forward transfer
KW - Micro-concentrator solar cell
KW - Photovoltaics
PY - 2018
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-470026
DO - https://doi.org/10.3762/bjnano.9.281
SN - 2190-4286
VL - 9
SP - 3025
EP - 3038
PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften
CY - Frankfurt, M.
AN - OPUS4-47002
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Brüngel, R.
A1 - Rückert, J.
A1 - Wohlleben, W.
A1 - Babick, F.
A1 - Ghanem, A.
A1 - Gaillard, C.
A1 - Mech, A.
A1 - Rauscher, H.
A1 - Hodoroaba, Vasile-Dan
A1 - Weigel, S.
A1 - Friedrich, C. M.
T1 - NanoDefiner e-Tool: An Implemented Decision Support Framework for Nanomaterial Identification
N2 - The European Commission’s recommendation on the definition of nanomaterial (2011/696/EU) established an applicable standard for material categorization. However, manufacturers face regulatory challenges during registration of their products. Reliable categorization is difficult and requires considerable expertise in existing measurement techniques (MTs). Additionally, organizational complexity is increased as different authorities’ registration processes require distinct reporting.
The NanoDefine project tackled these obstacles by providing the NanoDefiner e-tool: A decision support expert system for nanomaterial identification in a regulatory context. It providesMT recommendations for categorization of specific materials using a tiered approach (screening/confirmatory), and was constructed with experts from academia and industry to be extensible, interoperable, and adaptable for forthcoming revisions of the nanomaterial definition. An implemented MT-driven material categorization scheme allows detailed description. Its guided workflow is suitable for a variety of user groups. Direct feedback and explanation enable transparent decisions. Expert knowledge is Held in a knowledge base for representation of MT performance criteria and physicochemical particle type
properties. Continuous revision ensured data quality and validity. Recommendations were validated by independent case studies on industry-relevant particulate materials. Besides supporting material identification and registration, the free and open-source e-tool may serve as template for other expert systems within the nanoscience domain.
KW - EC nanomaterial definition
KW - Decision support
KW - Expert system
KW - Nanomaterial
KW - Nanoparticles
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492449
DO - https://doi.org/10.3390/ma12193247
VL - 12
IS - 19
SP - 3247
PB - MDPI
CY - Basel, CH
AN - OPUS4-49244
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Fletcher, D. C.
A1 - Hunter, R.
A1 - Xia, W.
A1 - Smales, Glen Jacob
A1 - Pauw, Brian Richard
A1 - Blackburn, E.
A1 - Kulak, A.
A1 - Xin, H.
A1 - Schnepp, Z.
T1 - Scalable synthesis of dispersible iron carbide (Fe3C) nanoparticles by ‘nanocasting’
N2 - Metal carbides have shown great promise in a wide range of applications due to their unique catalytic, electrocatalytic and magnetic properties. However, the scalable production of dispersible metal carbide nanoparticles remains a challenge. Here, we report a simple and scalable route to dispersible iron carbide (Fe3C) nanoparticles. This uses MgO nanoparticles as a removable ‘cast’ to synthesize Fe3C nanoparticles from Prussian blue (KFeIII[FeII(CN)6]). Electron tomography demonstrates how nanoparticles of the MgO cast encase the Fe3C nanoparticles to prevent sintering and agglomeration during the high-temperature synthesis. The MgO cast is readily removed with ethylenediaminetetraacetic acid (EDTA) to generate Fe3C nanoparticles that can be used to produce a colloidal ferrofluid or dispersed on a support material.
KW - Small-angle scattering
KW - SAXS
KW - Metal carbides
KW - Nanoparticles
KW - Nanocasting
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486295
DO - https://doi.org/10.1039/C9TA06876G
SN - 2050-7488
SN - 2050-7496
VL - 7
IS - 33
SP - 19506
EP - 19512
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-48629
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Elert, Anna Maria
A1 - Kanerva, M
A1 - Puolakka, A
A1 - Takala, T.M.
A1 - Mylläri, V
A1 - Jönkkäri, I
A1 - Sarlin, E
A1 - Seitsonen, J
A1 - Ruokolainen, J
A1 - Saris, P
A1 - Vuorinen, J
T1 - Antibacterial polymer fibres by rosin compounding and melt-spinning
N2 - The antibacterial features of natural pine/spruce rosin are well established, yet the functionality in various thermoplastics has not been surveyed. This work focuses on the processing of industrial grade purified rosin mixed with polyethylene (PE), polypropylene (PP), polylactic acid (PLA), polyamide (PA) and corn starch based biopolymer (CS). Homopolymer masterbatches were extrusion-compounded and melt-spun to form fibres for a wide range of products, such as filters, reinforcements, clothing and medical textiles. Due to the versatile chemical structure of rosin, it was observed compatible with all the selected polymers. In general, the rosin-blended systems were shear-thinning in a molten condition. The doped fibres spun of PE and PP indicated adequate melt-spinning capability and proper mechanical properties in terms of ultimate strength and Young's modulus. The antibacterial response was found dependent on the selected polymer. Especially PE with a 10 wt% rosin content showed significant antibacterial effects against Escherichia coli DH5α and Staphylococcus aureus ATCC 12598 when analysed in the Ringer's solution for 24 h.
KW - Rosin
KW - Antibacterial
KW - Thermoplastics
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481785
DO - https://doi.org/10.1016/j.mtcomm.2019.05.003
SN - 2352-4928
VL - 20
SP - 527
EP - 527
PB - Elsevier
AN - OPUS4-48178
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Haferkamp, Sebastian
A1 - Paul, Andrea
A1 - Michalchuk, Adam
A1 - Emmerling, Franziska
T1 - Unexpected polymorphism during a catalyzed mechanochemical Knoevenagel condensation
N2 - The transformation of a base-catalyzed, mechano-assisted Knoevenagel condensation of mono-fluorinated benzaldehyde derivatives (p-, m-, o-benzaldehyde) with malonodinitrile was investigated in situ and in real time. Upon milling, the para-substituted product was found to crystallize initially into two different polymorphic forms, depending on the quantity of catalyst used. For low catalyst concentrations, a mechanically metastable phase (monoclinic) was initially formed, converting to the mechanically stable phase (triclinic) upon further grinding. Instead, higher catalyst concentrations crystallize directly as the triclinic product. Inclusion of catalyst in the final product, as evidenced by mass spectrometric analysis, suggests this complex polymorphic pathway may be due to seeding effects. Multivariate analysis for the in situ Raman spectra supports this complex formation pathway, and offers a new approach to monitoring multi-phase reactions during ball milling.
KW - Ball milling
KW - C-C coupling
KW - In situ
KW - Mechanochemistry
KW - Multivariate data analysis
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481872
DO - https://doi.org/10.3762/bjoc.15.110
SN - 1860-5397
VL - 15
SP - 1141
EP - 1148
PB - Beilstein Insitut
CY - Frankfurt am Main
AN - OPUS4-48187
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Michalchuk, Adam
A1 - Trestman, M.
A1 - Rudic, S.
A1 - Portius, P.
A1 - Fincham, P.
A1 - Pulham, C.
A1 - Morrison, C.
T1 - Predicting the reactivity of energetic materials: an ab initio multi-phonon approach
N2 - The ease with which an energetic material (explosives, propellants, and pyrotechnics) can be initiated is a critical parameter to assess their safety and application. Impact sensitivity parameters are traditionally derived experimentally, at great cost and risk to safety. In this work we explore a fully ab initio Approach based on concepts of vibrational energy transfer to predict impact sensitivities for a series of chemically, structurally and energetically diverse molecular materials. The quality of DFT calculations is assessed for a subset of the materials by comparison with experimental inelastic neutron scattering spectra (INS). A variety of models are considered, including both qualitative and quantitative analysis of the vibrational spectra. Excellent agreement against experimental impact sensitivity is achieved by consideration of a multi-phonon ladder-type up-pumping mechanism that includes both overtone and combination pathways, and is improved further by the added consideration of temperature. This fully ab initio approach not only permits ranking of energetic materials in terms of their impact sensitivity but also provides a tool to guide the targeted design of advanced energetic compounds with tailored properties.
KW - Energetic Materials
KW - Prediction
KW - Density Functional Theory
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489328
DO - https://doi.org/10.1039/c9ta06209b
VL - 7
IS - 33
SP - 19539
EP - 19553
PB - RSC
AN - OPUS4-48932
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Greiser, Sebastian
A1 - Gluth, Gregor
A1 - Sturm, Patrick
A1 - Jäger, Christian
T1 - 29Si{27Al}, 27Al{29Si} and 27Al{1H} double-resonance NMR spectroscopy study of cementitious sodium aluminosilicate gels (geopolymers) and gel-zeolite composites
N2 - The influence of starting materials and synthesis route on the properties and the structure of cementitious sodium aluminosilicate gels is not fully understood, partly due their amorphous nature and the fact that they often contain residual reactants, which can make the results of single-pulse NMR spectroscopy applied to these materials difficult to interpret or ambiguous. To overcome some of these limitations, 29Si{27Al} TRAPDOR NMR as well as 27Al{29Si} and 27Al{1H} REDOR NMR spectroscopy were applied to materials synthesized by the one-part alkali-activation route from three different amorphous silica starting materials, including rice husk ash. The latter led to formation of a fully amorphous sodium aluminosilicate gel (geopolymer), while the materials produced from the other silicas contained amorphous phase and crystalline zeolites. Application of the double-resonance NMR methods allowed to identify hydrous alumina gel domains in the rice husk ash-based material as well as significantly differing amounts of residual silica in the three cured materials. Four-coordinated Al existed not only in the aluminosilicate gel framework but also in a water-rich chemical environment with only a small amount of Si in proximity, likely in the alumina gel or possibly present as extra-framework Al in the aluminosilicate gel. The results demonstrate how the employment of different silica starting materials determines the phase assemblage of one-part alkali-activated materials, which in turn influences their engineering properties such as the resistance against chemically/biologically aggressive media.
KW - Alkali-activated materials
KW - Solid-state NMR
KW - Aluminium hydroxide
KW - Rice husk ash
PY - 2018
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-469353
DO - https://doi.org/10.1039/C8RA09246J
SN - 2046-2069
VL - 8
IS - 70
SP - 40164
EP - 40171
PB - Royal Society of Chemistry
AN - OPUS4-46935
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Akbar, S.
A1 - Hasanain, S.K.
A1 - Ivashenko, O.
A1 - Dutka, M.V.
A1 - Akhtar, N.
A1 - De Hosson, J.Th.M.
A1 - Ali, Naveed
A1 - Rudolf, P.
T1 - Defect ferromagnetism in SnO2:Zn2+ hierarchical nanostructures: correlation between structural, electronic and magnetic properties
N2 - We report on the ferromagnetism of Sn1-xZnxO2 (x < 0.1) hierarchical nanostructures with various morphologies synthesized by a solvothermal route. A room temperature ferromagnetic and paramagnetic response was observed for all compositions, with a maximum in ferromagnetism for x = 0.04. The ferromagnetic behaviour was found to correlate with the presence of zinc on substitutional Sn sites and with a low oxygen vacancy concentration in the samples. The morphology of the nanostructures varied with zinc concentration. The strongest ferromagnetic response was observed in nanostructures with well-formed shapes, having nanoneedles on their surfaces. These nanoneedles consist of (110) and (101) planes, which are understood to be important in stabilizing the ferromagnetic defects. At higher zinc concentration the nanostructures become eroded and agglomerated, a phenomenon accompanied with a strong decrease in their ferromagnetic response. The observed trends are explained in the light of recent computational studies that discuss the relative stability of ferromagnetic defects on various surfaces and the role of oxygen vacancies in degrading ferromagnetism via an increase in free electron concentration.
KW - Ferromagnetism
KW - Nanostructures
KW - Magnetic properties
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-473014
DO - https://doi.org/10.1039/c9ra00455f
SN - 2046-2069
VL - 9
IS - 7
SP - 4082
EP - 4091
PB - Royal Society of Chemistry
AN - OPUS4-47301
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Radnik, Jörg
A1 - Dang, T. T. H.
A1 - Gatla, S.
A1 - Raghuwanshi, V. S.
A1 - Tatchev, D.
A1 - Hoell, A.
T1 - Identifying the location of Cu ions in nanostructured SAPO-5 molecular sieves and its impact on the redox properties
N2 - Combining X-ray Absorption Fine Spectroscopy (XAFS) with Anomalous Small-Angle X-ray Scattering (ASAXS) determines the location of Cu2+ ions in silicoaluminophosphate (SAPO-5) frameworks prepared by hydrothermal crystallization or impregnation. As expected, for the hydrothermally prepared sample, incorporation in the SAPO-5 framework was observed. For the first time preferential location of Cu2+ ions at the inner and outer surfaces of the framework is determined. Temperature-Programmed Reduction (TPR) and X-ray Photoelectron Spectroscopy (XPS) investigations demonstrated that such Cu2+ is stable in an argon (Ar) atmosphere up to 550 °C and can only be reduced under a hydrogen atmosphere. In contrast, Cu2+ deposited by impregnation on the pure SAPO-5 framework can be easily reduced to Cu+ in an Ar atmosphere. At lower Cu amounts, mononuclear tetrahedrally coordinated Cu species were formed which are relatively stable in the monovalent form. In contrast, at higher Cu amounts, CuO particles were found which change easily between the mono- and bivalent species.
KW - Nanostructured material
KW - Molecular sieves
KW - X-ray absorption Fine Spectroscopy
KW - Anomalous Small Angle X-ray Scattering
KW - X-ray Photoelectron Spectroscopy
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474793
DO - https://doi.org/10.1039/c8ra10417d
SN - 2046-2069
VL - 9
IS - 12
SP - 6429
EP - 6437
PB - RSC
AN - OPUS4-47479
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Domonov, D.P.
A1 - Pechenyuk, S.I.
A1 - Semushina, Y.P.
A1 - Yusenko, Kirill
T1 - Solid state transformation in inner coordination sphere of [Co(NH3)6][Fe(C2O4)3]·3H2O as a route to access catalytically active Co-Fe materials
N2 - Thermal decomposition of [Co(NH₃)₆][Fe(C₂O₄)₃]∙3H₂O in argon atmosphere, at a low heating rate (3°/min), and in large amounts of the initial complex (~0.1 mole), has been studied. It was possible to distinguish four decomposition steps upon heating: In the temperature range of 50⁻100 °C-the loss of crystal water; 100⁻190 °C-stability region of dehydrated complex; 230⁻270 °C-the range of stability of intermediate phase with the formula CoFe(NH₃)₂(C₂O₄)₂; 270⁻350 °C-thermal decomposition of the intermediate with the formation of metallic products and further air oxidation with the formation of Co1.5Fe1.5O₄. Catalytic properties of thermolysis products were tested in the decomposition reaction of H₂O₂ (inactive), oxidation of acetone (average activity), and decomposition of ammonium perchlorate (highly active).
KW - Double complex salts
KW - Catalysts
KW - Single-source precursors
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474014
DO - https://doi.org/10.3390/ma12020221
SN - 1996-1944
VL - 12
IS - 2
SP - 221, 1
EP - 10
PB - mdpi
CY - Zürich
AN - OPUS4-47401
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Joseba Ayerdi, J.
A1 - Slachciak, Nadine
A1 - Llavori, I.
A1 - Zabala, A.
A1 - Aginagalde, A.
A1 - Bonse, Jörn
A1 - Spaltmann, Dirk
T1 - On the role of a ZDDP in the tribological performance of femtosecond laser-induced periodic surface structures on titanium alloy against different counterbody materials
N2 - Laser-induced periodic surface structures (LIPSS, ripples) with ~500–700 nm period were produced on titanium alloy (Ti6Al4V) surfaces upon scan processing in air by a Ti:sapphire femtosecond laser. The tribological performance of the surfaces were qualified in linear reciprocating sliding tribological tests against balls made of different materials using different oilbased lubricants. Extending our previous work, we studied the admixture of the additive 2-ethylhexyl-zinc-dithiophosphate to a base oil containing only anti-oxidants and temperature stabilizers. The presence of this additive along with the variation of the chemical composition of the counterbodies allows us to explore the synergy of the additive with the laseroxidized nanostructures.
KW - Additives
KW - Surface structures
KW - Wear
KW - Friction
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-488458
DO - https://doi.org/10.3390/lubricants7090079
SN - 2075-4442
VL - 7
SP - 79, 1
EP - 13
PB - MDPI
AN - OPUS4-48845
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H. R.
A1 - Weidner, Steffen
A1 - Scheliga, F.
T1 - Synthesis of cyclic poly(l-lactide) catalyzed by Bismuth salicylates-A combination of two drugs
N2 - l‐lactide was polymerized in bulk at 160 or 180°C with mixtures of bismuth subsalicylate (BiSub) and salicylic (SA) as catalysts. The SA/Bi ratio and the monomer/Bi ratio were varied. The highest molecular weights (weight average, Mw) were achieved at a SA/Bi ratio of 1/1 (Mw up to 92 000 g mol−1). l‐Lactide was also polymerized with combinations of BiSub and silylated SA, and Mw values up to 120 000 g mol−1 were achieved at 180°C. MALDI‐TOF mass spectrometry and Mark‐Houwink‐Sakurada measurements proved that under optimized reaction conditions the resulting polylactides consist of cycles.
KW - Polylactide
KW - MALDI-TOF MS
KW - Cyclization
KW - Catalyst
KW - Salicylate
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-488622
DO - https://doi.org/10.1002/pola.29473
SN - 0887-624X
SN - 1099-0518
SP - 29473
PB - Wiley
AN - OPUS4-48862
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ahmed, R.
A1 - Vaishampayan, A.
A1 - Cuellar-Camacho, J. L.
A1 - Wight, D. J.
A1 - Donskyi, Ievgen
A1 - Unger, Wolfgang
A1 - Grohmann, E.
A1 - Haag, R.
A1 - Wagner, O.
T1 - Multivalent Bacteria Binding by Flexible Polycationic Microsheets Matching Their Surface Charge Density
N2 - Aiming at the overall negative surface charge of bacteria, a new strategy of antibacterial agents based on large polymer-modified graphene oxide (GO) sheets is assessed. The presented flexible, polycationic Sheets match the size and charge density of the Escherichia coli surface charge density (2 × 1014 cm−2). These matching parameters create an unspecific but very strong bacteria adsorber by multivalent, electrostatic attraction.
Their interaction with bacteria is visualized via atomic force and confocal microscopy and shows that they effectively bind and wrap around E. coli cells, and thereby immobilize them. The incubation of Gram-negative and -positive bacteria (E. coli and methicillin-resistant Staphylococcus aureus, MRSA) with these polycationic sheets leads to the inhibition of proliferation and a reduction of the colony forming bacteria over time.
This new type of antibacterial agent acts in a different mode of Action than classical biocides and could potentially be employed in medicinal, technical, or agriculture applications. The presented microsheets and their unspecific binding of cell interfaces could further be employed as adsorber material for bacterial filtration or immobilization for imaging, analysis, or sensor technologies.
KW - Surface charge
KW - Bacteria
KW - Graphene oxide
KW - Escherichia coli
KW - XPS
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509651
DO - https://doi.org/10.1002/admi.201902066
VL - 7
IS - 15
SP - 1902066
PB - WILEY-VCH Verlag GmbH & Co. KGaA
CY - Weinheim
AN - OPUS4-50965
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stroh, Julia
A1 - Feiler, Torvid
A1 - Ali, N. Z.
A1 - Minas da Piedade, M. E.
A1 - Emmerling, Franziska
T1 - Mechanistic Insights into a Sustainable Mechanochemical Synthesis of Ettringite
N2 - Mechanochemistry offers an environmentally benign and facile synthesis method for a variety of cement paste constituents. In addition, these methods can be used to selectively tune the properties of cement components. The mineral ettringite is an important component of cementitious materials and has additional technological potential due to its ion exchange properties.
Synthesis of ettringite via mechanochemistry is an environmentally friendly alternative to conventional wet-chemical synthesis established in industry. This contribution explores the mechanism of a two-step mechanochemical synthesis of ettringite, which was previously found to greatly improve the reaction conversion as compared with one-pot synthesis. The crystallinity of Al(OH)3 was found to decrease during the first stage of this mechanochemical synthesis. This was correlated to a significant decrease in the particle size of Al(OH)3 in this stage. No other significant changes were found for the other components, suggesting that mechanochemical activation of Al(OH)3 is responsible for the enhanced formation of ettringite by the two-step approach. The environmentally friendly approach developed for ettringite synthesis offers a versatile synthetic strategy, which can be applied to synthesise further cementitious materials.
KW - Ettringite
KW - Mechanochemistry
KW - Sustainability
KW - X-ray diffraction
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489172
DO - https://doi.org/10.1002/open.201900215
VL - 8
IS - 7
SP - 1012
EP - 1019
PB - ChemPubSoc
AN - OPUS4-48917
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ghasem Zadeh Khorasani, Media
A1 - Elert, Anna Maria
A1 - Hodoroaba, Vasile-Dan
A1 - Agudo Jácome, Leonardo
A1 - Altmann, Korinna
A1 - Silbernagl, Dorothee
A1 - Sturm, Heinz
T1 - Short- and long-range mechanical and chemical interphases caused by interaction of Boehmite (γ-AlOOH) with anhydride-cured epoxy resins
N2 - Understanding the interaction between boehmite and epoxy and the formation of their interphases with different mechanical and chemical structures is crucial to predict and optimize the properties of epoxy-boehmite nanocomposites. Probing the interfacial properties with atomic force microscopy (AFM)-based methods, especially particle-matrix long-range interactions, is challenging. This is due to size limitations of various analytical methods in resolving nanoparticles and their interphases, the overlap of interphases, and the effect of buried particles that prevent the accurate interphase property measurement. Here, we develop a layered model system in which the epoxy is cured in contact with a thin layer of hydrothermally synthesized boehmite. Different microscopy methods are employed to evaluate the interfacial properties. With intermodulation atomic force microscopy (ImAFM) and amplitude dependence force spectroscopy (ADFS), which contain information about stiffness, electrostatic, and van der Waals forces, a soft interphase was detected between the epoxy and boehmite. Surface potential maps obtained by scanning Kelvin probe microscopy (SKPM) revealed another interphase about one order of magnitude larger than the mechanical interphase. The AFM-infrared spectroscopy (AFM-IR) technique reveals that the soft interphase consists of unreacted curing agent. The long-range electrical interphase is attributed to the chemical alteration of the bulk epoxy and the formation of new absorption bands.
KW - Nanocomposites
KW - Interphase
KW - Intermodulation AFM
KW - Electron microscopy
KW - Infrared nano AFM
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483672
UR - https://www.mdpi.com/2079-4991/9/6/853/htm
DO - https://doi.org/10.3390/nano9060853
SN - 2079-4991
VL - 9
IS - 6
SP - 853, 1
EP - 20
PB - MDPI
AN - OPUS4-48367
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Huang, J.
A1 - Tarábek, J.
A1 - Kulkarni, R.
A1 - Wang, Cui
A1 - Dračínský, M.
A1 - Smales, Glen Jacob
A1 - Pauw, Brian Richard
A1 - Resch-Genger, Ute
A1 - Bojdys, M. J.
T1 - A π-conjugated, covalent phosphinine framework
N2 - Structural modularity of polymer frameworks is a key advantage of covalent organic polymers, however, only C, N, O, Si and S have found their way into their building blocks so far. Here, we expand the toolbox available to polymer and materials chemists by one additional nonmetal, phosphorus. Starting with a building block that contains a λ⁵‐phosphinine (C₅P) moiety, we evaluate a number of polymerisation protocols, finally obtaining a π‐conjugated, covalent phosphinine‐based framework (CPF‐1) via Suzuki‐Miyaura coupling. CPF‐1 is a weakly porous polymer glass (72.4 m2 g‐1 N2 BET at 77 K) with green fluorescence (λmax 546 nm) and extremely high thermal stability. The polymer catalyzes hydrogen evolution from water under UV and visible light irradiation without the need for additional co‐catalyst at a rate of 33.3 μmol h‐¹ g‐¹. Our results demonstrate for the first time the incorporation of the phosphinine motif into a complex polymer framework. Phosphinine‐based frameworks show promising electronic and optical properties that might spark future interest in their applications in light‐emitting devices and heterogeneous catalysis.
KW - Phosphinine
KW - Fully aromatic frameworks
KW - Suzuki-Miyaura coupling
KW - Polymers
KW - Fluorescence
KW - Small-angle scattering
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485330
DO - https://doi.org/10.1002/chem.201900281
SP - 2
EP - 10
PB - Wiley VCH-Verlag
CY - Weinheim
AN - OPUS4-48533
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Belenguer, A.
A1 - Michalchuk, Adam
A1 - Lampronti, G
A1 - Sanders, J
T1 - Understanding the unexpected effect of frequency on the kinetics of a covalent reaction under ball-milling conditions
N2 - We here explore how ball-mill-grinding frequency affects the kinetics of a disulfide exchange reaction. Our kinetic data show that the reaction progress is similar at all the frequencies studied (15–30 Hz), including a significant induction time before the nucleation and growth process starts. This indicates that to start the reaction an initial energy accumulation is necessary. Other than mixing, the energy supplied by the mechanical treatment has two effects: (i) reducing the crystal size and (ii) creating defects in the structure. The crystal-breaking process is likely to be dominant at first becoming less important later in the process when the energy supplied is stored at the molecular level as local crystal defects. This accumulation is taken here to be the rate-determining step. We suggest that the local defects accumulate preferentially at or near the crystal surface. Since the total area increases exponentially when the crystal size is reduced by the crystal-breaking process, this can further explain the exponential dependence of the onset time on the milling frequency.
KW - Mechanochemistry
KW - Kinetics
KW - Diffraction
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483361
DO - https://doi.org/10.3762/bjoc.15.120
SN - 2195-951X
VL - 15
SP - 1226
EP - 1235
PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften
CY - Frankfurt, M.
AN - OPUS4-48336
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hahn, Marc Benjamin
T1 - Temperature in micromagnetism: Cell size and scaling effects of the stochastic Landau-Lifshitz equation
N2 - The movement of the macroscopic magnetic moment in ferromagnetic systems can be described by the Landau-Lifshitz (LL) or Landau-Lifshitz-Gilbert (LLG) equation. These equations are strictly valid only at absolute zero temperature. To include temperature effects a stochastic version of the LL or LLG equation for a spin density of one per unit cell can be used instead. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion regarding simulation cell size and temperature has to be established. Based on energetic considerations, a conversion for ferromagnetic bulk and thin film systems is proposed. The conversion is tested in micromagnetic simulations which are performed with the Object Oriented Micromagnetic Framework (OOMMF). The Curie temperatures of bulk Nickel, Cobalt and Iron systems as well as Nickel thin-film systems with thicknesses between 6.3 mono layer (ML) and 31ML are determined from micromagnetic simulations. The results show a good agreement with experimentally determined Curie temperatures of bulk and thin film systems when temperature scaling is performed according to the presented model.
KW - Micromagnetism
KW - LLG
KW - LL equation
KW - Landau Lifshitz equation
KW - Landau Lifshitz Gilbert equation
KW - Stochastic Landau Lifshitz equation
KW - Stochastic Landau Lifshitz Gilbert equation
KW - Curie temperature
KW - Magnetic Nanoparticles
KW - Thin film systems
KW - Temeprature scaling
KW - Phase transition
KW - Magnet coupling
KW - Ferromagnetism
KW - Superparamagnetism
KW - Paramagnetism
KW - Ni
KW - Co
KW - Fe
KW - Steel
KW - Nickel
KW - Cobalt
KW - Iron
KW - Temperature effects
KW - Cell size
KW - Damping factor
KW - Gamma
KW - Alpha
KW - Spin
KW - Magnetic moment
KW - Magnetic interacion
KW - Magnetization dynamics
KW - Domain wall
KW - Exchange length
KW - temeprature dependent exchange length
KW - Bloch wall
KW - Neel wall
KW - Exchange interaction
KW - Magnetic anisotropy
KW - Simulation
KW - OOMMF
KW - Object oriented micromagnetic framework
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-484610
DO - https://doi.org/10.1088/2399-6528/ab31e6
VL - 3
IS - 7
SP - 075009-1
EP - 075009-8
PB - IOPscience
CY - England
AN - OPUS4-48461
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schwibbert, Karin
A1 - Menzel, F.
A1 - Epperlein, N.
A1 - Bonse, Jörn
A1 - Krüger, Jörg
T1 - Bacterial adhesion on femtosecond laser-modified polyethylene
N2 - In this study, femtosecond laser-induced sub-micrometer structures are generated to modify polyethylene (PE) surface topographies. These surfaces were subjected to bacterial colonization studies with Escherichia coli and Staphylococcus aureus as test strains. The results reveal that the nanostructures do not influence S. aureus coverage, while the adhesion of E. coli is reduced.
KW - Bacterial adhesion
KW - Laser-modified surface
KW - Polyethylene
KW - Laser-induced nanostructures
KW - Biofilm
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492280
DO - https://doi.org/10.3390/ma12193107
VL - 12
IS - 19
SP - 3107
PB - MDPI
CY - Basel, Schweiz
AN - OPUS4-49228
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weigert, Florian
A1 - Müller, A.
A1 - Häusler, I.
A1 - Geißler, Daniel
A1 - Skroblin, D.
A1 - Unger, Wolfgang
A1 - Radnik, Jörg
A1 - Resch-Genger, Ute
T1 - Combining HR‑TEM and XPS to elucidate the core–shell structure of ultrabright CdSe/CdS semiconductor quantum dots
N2 - Controlling thickness and tightness of surface passivation shells is crucial for many applications of core–shell nanoparticles (NP). Usually, to determine shell thickness, core and core/shell particle are measured individually requiring the availability of both nanoobjects. This is often not fulfilled for functional nanomaterials such as many photoluminescent semiconductor quantum dots (QD) used for bioimaging, solid state lighting, and display technologies as the core does not show the applicationrelevant functionality like a high photoluminescence (PL) quantum yield, calling for a whole nanoobject approach. By combining high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), a novel whole nanoobject approach is developed representatively for an ultrabright oleic acid-stabilized, thick shell CdSe/CdS QD with a PL quantum yield close to unity. The size of this spectroscopically assessed QD, is in the range of the information depth of usual laboratory XPS. Information on particle size and monodispersity were validated with dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) and compared to data derived from optical measurements. In addition to demonstrating the potential of this novel whole nanoobject approach for determining architectures of small nanoparticles, the presented results also highlight challenges faced by different sizing and structural analysis methods and method-inherent uncertainties.
KW - Photoluminescence
KW - Single particle
KW - Microscopy
KW - Particle architecture
KW - Thickness
KW - SAXS
KW - Shell
KW - XPS
KW - TEM
KW - Semiconductor
KW - Quantum dot
KW - Photophysics
KW - Quantum yield
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517911
DO - https://doi.org/10.1038/s41598-020-77530-z
VL - 10
IS - 1
SP - 20712
PB - Springer Nature
AN - OPUS4-51791
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Anja
A1 - Sparnacci, K.
A1 - Unger, Wolfgang
A1 - Tougaard, S.
T1 - Determining nonuniformities of core-shell nanoparticle coatings by analysis of the inelastic background of X-ray photoelectron spectroscopy survey spectra
N2 - Most real core-shell nanoparticle (CSNP) samples deviate from an ideal core-shell structure potentially having significant impact on the particle properties. An ideal structure displays a spherical core fully encapsulated by a shell of homogeneous thickness, and all particles in the sample exhibit the same shell thickness. Therefore,
analytical techniques are required that can identify and characterize such deviations.
This study demonstrates that by analysis of the inelastic background in X-ray photoelectron spectroscopy (XPS) survey spectra, the following types of deviations can be identified and quantified: the nonuniformity of the shell thickness within a nanoparticle sample and the incomplete encapsulation of the cores by the shell material. Furthermore, CSNP shell thicknesses and relative coverages can be obtained. These results allow for a quick and straightforward comparison between several batches of a specific CSNP, different coating approaches, and so forth. The presented XPS methodology requires a submonolayer distribution of CSNPs on a substrate.
Poly(tetrafluoroethylene)-poly(methyl methacrylate) and poly(tetrafluoroethylene)-polystyrene polymer CSNPs serve as model systems to demonstrate the applicability of the approach.
KW - Core-shell
KW - Nanoparticles
KW - Inelastic background
KW - Polymers
KW - QUASES
KW - XPS
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-511315
DO - https://doi.org/10.1002/sia.6865
SN - 0142-2421
SN - 1096-9918
VL - 52
SP - 1
EP - 8
PB - Wiley
CY - Chichester
AN - OPUS4-51131
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kovacevic, E.
A1 - Strunskus, T.
A1 - Santhosh, N. M.
A1 - Zavasnik, Z.
A1 - Unger, Wolfgang
A1 - Sauvage, T.
A1 - Ammar, M.-R.
A1 - Cvelbar, U.
A1 - Berndt, J.
T1 - Thermal stability studies of plasma deposited hydrogenated carbon nitride nanostructures
N2 - Thermally stable carbon nitride nanostructures have potential applications in surface coatings and automotive fields. In this work, hydrogenated nitrogen-rich carbon nitride nanoparticles have been synthesised via low-pressure low-power plasma vapour deposition technique from methane/Nitrogen gas mixture in a dry process. Thermal stability of the initially prepared hydrogenated carbon Nitride structures has been analysed by near-edge X-ray absorption fine-structure spectroscopy (NEXAFS, insitu), Raman spectroscopy, scanning and transmission electron microscopy and nuclear reaction Analysis (NRA). Thermal studies reveal the excellent stability of the material and nitrogen-rich characteristics (N/C ratio 0.5e0.2 ± 0.01). The obtained results suggest transformation of sp3-rich as-deposited carbon Nitride into sp2-carbon phase with more graphitic features upon thermal annealing. Such in-situ thermal studies of plasma deposited carbon nitrides confirm the conversion of sp3-rich phase to sp2-rich carbon phase at the critical temperature (about 450 K), without a huge loss in nitrogen content. The analysis revealed that the material is a stable plasma deposit after this critical temperature up to >1100 K. Additionally, super hydrophilic carbon nitride nanostructure transforms into a hydrophobic surface after thermal annealing.
These thermally stable hydrophobic carbon nitride nanoparticles could be used as a promising material for the hydrophobic coatings for various applications, especially for harsh conditions.
KW - Carbon nanoparticles
KW - Hydrogenated nanostructures
KW - Plasma deposition
KW - NEXAFS
KW - Thermal annealing
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-536163
DO - https://doi.org/10.1016/j.carbon.2021.08.008
SN - 0008-6223
VL - 184
SP - 82
EP - 90
PB - Elsevier Ltd.
AN - OPUS4-53616
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Anja
A1 - Krahl, T.
A1 - Radnik, Jörg
A1 - Wagner, Andreas
A1 - Werner, W. S. M.
A1 - Ritter, B.
A1 - Kemnitz, E.
A1 - Unger, Wolfgang
T1 - Chemical in-depth analysis of (Ca/Sr)F2 core–shell like nanoparticles by X-ray photoelectron spectroscopy with tunable excitation energy
N2 - The fluorolytic sol–gel synthesis is applied with the intention to obtain two different types of core–shell nanoparticles, namely, SrF2–CaF2 and CaF2–SrF2. In two separate fluorination steps for core and shell formation, the corresponding metal lactates are reacted with anhydrous HF in ethylene glycol. Scanning transmission electron microscopy (STEM) and dynamic light scattering (DLS) confirm the formation of particles with mean dimensions between 6.4 and 11.5 nm. The overall chemical composition of the particles during the different reaction steps is monitored by quantitative Al Kα excitation X-ray photoelectron spectroscopy (XPS). Here, the formation of stoichiometric metal fluorides (MF2) is confirmed, both for the core and the final core–shell particles. Furthermore, an in-depth analysis by synchrotron radiation XPS (SR-XPS) with tunable excitation energy is performed to confirm the core–Shell character of the nanoparticles. Additionally, Ca2p/Sr3d XPS intensity ratio in-Depth profiles are simulated using the software Simulation of Electron Spectra for Surface Analysis (SESSA). In principle, core–shell like particle morphologies are formed but without a sharp interface between calcium and strontium containing phases.
Surprisingly, the in-depth chemical distribution of the two types of nanoparticles is equal within the error of the experiment. Both comprise a SrF2-rich core domain and CaF2-rich shell domain with an intermixing zone between them. Consequently, the internal morphology of the final nanoparticles seems to be independent from the synthesis chronology.
KW - Metal fluorides
KW - Sol-gel synthesis
KW - Synchrotron radiation
KW - X-ray photoelectron spectroscopy
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522284
DO - https://doi.org/10.1002/sia.6937
SN - 0142-2421
VL - 53
IS - 5
SP - 494
EP - 508
PB - Wiley VCH
AN - OPUS4-52228
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kjaervik, Marit
A1 - Ramstedt, M.
A1 - Schwibbert, Karin
A1 - Dietrich, P. M
A1 - Unger, Wolfgang
T1 - Comparative Study of NAP-XPS and Cryo-XPS for the Investigation of Surface Chemistry of the Bacterial Cell-Envelope
N2 - Bacteria generally interact with the environment via processes involving their cell-envelope. Thus, techniques that may shed light on their surface chemistry are attractive tools for providing an understanding of bacterial interactions. One of these tools is Al Kα-excited photoelectron spectroscopy (XPS) with its estimated information depth of <10 nm. XPS-analyses of bacteria have been performed for several decades on freeze-dried specimens in order to be compatible with the vacuum in the analysis chamber of the spectrometer. A limitation of these studies has been that the freeze-drying method may collapse cell structure as well as introduce surface contaminants. However, recent developments in XPS allow for analysis of biological samples at near ambient pressure (NAP-XPS) or as frozen hydrated specimens (cryo-XPS) in vacuum. In this work, we have analyzed bacterial samples from a reference strain of the Gram-negative bacterium Pseudomonas fluorescens using both techniques. We compare the results obtained and, in general, observe good agreement between the two techniques. Furthermore, we discuss advantages and disadvantages with the two analysis approaches and the output data they provide. XPS reference data from the bacterial strain are provided, and we propose that planktonic cells of this strain (DSM 50090) are used as a reference material for surface chemical analysis of bacterial systems.
KW - P. Fluorescens
KW - Cryo XPS
KW - NAP-XPS
KW - DSM 5009
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525640
DO - https://doi.org/10.3389/fchem.2021.666161
VL - 9
SP - Article 666161
PB - Frontiers
CY - Switzerland
AN - OPUS4-52564
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Unger, Wolfgang
A1 - Senoner, M.
A1 - Stockmann, Jörg M.
A1 - Fernandez, V.
A1 - Fairley, N.
A1 - Passiu, C.
A1 - Spencer, N. D.
A1 - Rossi, A.
T1 - Summary of ISO/TC 201 International Standard ISO 18516:2019 Surface chemical analysis - Determination of lateral resolution and sharpness in beam-based methods with a range from nanometres to micrometres and its implementation for imaging laboratory X-ray photoelectron spectrometers (XPS)
N2 - ISO 18516:2019 Surface chemical analysis—Determination of lateral resolution and sharpness in beam-based methods with a range from nanometres to micrometres revises ISO 18516:2006 Surface chemical analysis—Auger electron spectroscopy and X-ray photoelectron spectroscopy—Determination of lateral resolution. It implements three different methods delivering parameters useful to express the lateral resolution: (1) the straight edge method, (2) the narrow line method and (3) the grating method. The theoretical background of these methods is introduced in ISO/TR 19319:2013 Surface chemical analysis—Fundamental approaches to determination of lateral resolution and sharpness in beam-based methods. The revised International Standard ISO 18516 delivers standardized procedures for the determination of the (1) effective lateral resolution by imaging of square-wave gratings, the (2) lateral resolution expressed as the parameter D12–88 characterizing the steepness of the sigmoidal edge spread function (ESF) determined by imaging a straight edge and (3) the lateral resolution expressed as the full width of half maximum of the line spread function (LSF), wLSF, determined by imaging a narrow line. The last method also delivers information on the shape of the LSF, which characterizes an individual imaging instrument. Finally, the implementation of all three standardized methods in the field of imaging laboratory X-ray photoelectron spectroscopy (XPS) is shortly presented. This part of the letter is based on the use of a new test sample developed at ETH Zurich, Switzerland. This test sample displays a micrometre scaled pattern motivated by the resolving power of recent imaging XPS instruments.
KW - Grating method
KW - Imaging AES
KW - Imaging SIMS
KW - Imaging XPS
KW - Lateral resolution
KW - Narrow line method
KW - Noise in image
KW - Resolution criterion
KW - Straight edge method
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-536330
DO - https://doi.org/10.1002/sia.7025
SN - 1096-9918
VL - 54
IS - 4
SP - 320
EP - 327
PB - Wiley
CY - Chichester
AN - OPUS4-53633
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Steiner, S.
A1 - Heldt, J.
A1 - Sobol, Oded
A1 - Unger, Wolfgang
A1 - Frömeling, T.
T1 - Influence of oxygen vacancies on core-shell formation in solid solutions of (Na,Bi)TiO3 and SrTiO3
N2 - Solid solutions of (Na,Bi)TiO3 (NBT) and SrTiO3 (ST) are materials of interest for high-strain or high-energy density capacitor applications. Often, they exhibit chemical heterogeneity and develop core-shell structures during regular solid-state synthesis with an NBT-rich core. In this case, the NBT forms first so that the strontium needs to diffuse into the material to reach chemical homogeneity. Depending on the presence of core-shell structures, the electrical properties can vary drastically. In this work, we rationalize the effect of variations in oxygen vacancy concentration by Fe-acceptor and Nb-donor doping. It can be shown that a diffusion couple of strontium and oxygen is responsible for chemical homogenization and that the oxygen vacancy content can control the formation of a core-shell structure.
KW - Lead-free ceramics
KW - Bismuth titanates
KW - Core-shell structures
KW - Diffusion/diffusivity
KW - Ferroelectricity/ferroelectric materials
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525988
DO - https://doi.org/10.1111/jace.17845
SP - 1
EP - 10
PB - Wiley Periodicals LLC, John Wiley & Sons, Inc.
AN - OPUS4-52598
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Röhsler, Andreas
A1 - Sobol, Oded
A1 - Unger, Wolfgang
A1 - Böllinghaus, Thomas
T1 - Comprehensive study of deuterium-induced effects in in austenitic stainless steel AISI 304L
N2 - The damaging impact of hydrogen on the austenitic stainless steel AISI 304 L was analysed.
To this aim, samples were charged electrochemically with the hydrogen isotope deuterium (2H, D) and examined with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and electron backscatter diffraction (EBSD). The fusion of the obtained chemical and structural information revealed local enrichment of deuterium in austenite, transformation into martensite, crack formation and severe roughening of the specimen surface. The results indicated that martensite was not only formed during charging but also during Desorption and ToF-SIMS examinations. Furthermore, cross-sections of deuterium-charged samples revealed that in preferred deformation bands a g/ε/a 0 evolution is taking place.
By means of microscopic analyses and carrier gas hot extraction (CGHE), it was found that the use of NaAsO2 as recombination poison decreased the uptake of hydrogen significantly and resulted in severe precipitation on the specimen surfaces. This is in contrast to the popular presumption that NaAsO2 enhances the uptake of hydrogen (and
deuterium) during electrochemical charging by hampering its recombination from Atoms to molecules.
KW - AISI 304L
KW - Hydrogen
KW - ToF-SIMS
KW - Deuterium
KW - Martensite
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-477540
DO - https://doi.org/10.1016/j.ijhydene.2019.03.058
SN - 0360-3199
SN - 1879-3487
VL - 44
IS - 23
SP - 12228
EP - 12238
PB - Elsevier Ltd.
AN - OPUS4-47754
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Anja
A1 - Swaraj, S.
A1 - Sparnacci, K.
A1 - Unger, Wolfgang
T1 - Shell thickness determination for PTFE‐PS core‐shell nanoparticles using scanning transmission X‐ray microscopy (STXM)
N2 - A scanning transmission X‐ray microscopy (STXM)‐based methodology is introduced for determining the dimensions (shell thickness, core and total diameter) of core‐shell nanoparticles, which exhibit a strong X‐ray absorption contrast and a well‐defined interface between core and shell material. A low radiation dosage during data acquisition and, therefore, less X‐ray beam‐induced damage of the sample is achieved by recording STXM images only at 2 predetermined energies of maximum Absorption contrast, instead of recording a stack of images across the whole absorption edge.
A model core‐shell nanoparticle, polytetrafluoroethylene (PTFE) cores with polystyrene (PS) shell, is used for demonstration. Near‐edge X‐ray absorption fine structure spectroscopy confirms the significant difference in X‐ray absorption behavior between PTFE and PS. Additionally, because of the insolubility of styrene in PTFE a well‐defined interface between particle core and shell is expected. To validate the STXM results, both the naked PTFE cores as well as the complete core‐shell nanoparticles are examined by scanning electron microscopy (SEM). The introduced STXM‐based methodology yields particle dimensions in agreement with the SEM results and provides additional information such as the position of the particle core, which cannot be extracted from a SEM micrograph.
T2 - European conference on applications of surface and interface analysis (ECASIA'17)
CY - Montpellier, France
DA - 24.09.2017
KW - Core-shell nanoparticles
KW - Polymers
KW - PS
KW - PTFE
KW - SEM
KW - STXM
PY - 2018
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-449700
DO - https://doi.org/10.1002/sia.6464
SN - 1096-9918
SN - 0142-2421
VL - 50
IS - 11
SP - 1077
EP - 1082
PB - John Wiley & Sons
CY - Hoboken, New Jersey, USA
AN - OPUS4-44970
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kjaervik, Marit
A1 - Schwibbert, Karin
A1 - Dietrich, P.
A1 - Thissen, A.
A1 - Unger, Wolfgang
T1 - Surface characterisation of Escherichia coli under various conditions by near-ambient pressure XPS
N2 - Bacteria are inherently in a hydrated state and therefore not compatible to ultra-high vacuum techniques such as XPS without prior sample preparation involving freeze drying or fast freezing.
This has changed with the development of near-ambient pressure (NAP)-XPS, which makes it possible to characterise the bacterial surface with minimal sample preparation. This paper presents NAP-XPS measurements of Escherichia coli under various NAP conditions: at 11 mbar in a humid environment, at 2 mbar after drying in the chamber, pre-dried at 4 mbar, and at 1 mbar after overnight pumping at 10^−4 mbar. The high-resolution spectra of carbon, nitrogen, and oxygen are presented and found to be in general agreement with XPS measurements from freeze-dried and fast-frozen bacteria. However, it was found that the amount of carbon components associated with polysaccharides increases relative to aliphatic carbon during drying and increases further after overnight pumping. This implies that drying has an impact on the bacterial surface.
T2 - European conference on applications of surface and interface analysis (ECASIA'17)
CY - Montpellier, France
DA - 24.09.2018
KW - Bacteria
KW - E. coli
KW - NAP-XPS
PY - 2018
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454047
DO - https://doi.org/10.1002/sia.6480
SN - 0142-2421
SN - 1096-9918
VL - 50
IS - 11
SP - 996
EP - 1000
PB - John Wiley & Sons
CY - Hoboken, New Jersey, USA
AN - OPUS4-45404
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Afantitis, A.
A1 - Melagraki, G.
A1 - Isigonis, P.
A1 - Tsoumanis, A.
A1 - Varsou, D. D.
A1 - Valsami-Jones, E.
A1 - Papadiamantis, A.
A1 - Ellis, L.-J. A.
A1 - Sarimveis, H.
A1 - Doganis, P.
A1 - Karatzas, P.
A1 - Tsiros, P.
A1 - Liampa, I.
A1 - Lobaskin, V.
A1 - Greco, D.
A1 - Serra, A.
A1 - Kinaret, P. A. S.
A1 - Saarimäki, L. A.
A1 - Grafström, R.
A1 - Kohonen, P.
A1 - Nymark, P.
A1 - Willighagen, E.
A1 - Puzyn, T.
A1 - Rybinska-Fryca, A.
A1 - Lyubartsev, A.
A1 - Jensen, K. A.
A1 - Brandenburg, J. G.
A1 - Lofts, S.
A1 - Svendsen, C.
A1 - Harrison, S.
A1 - Maier, D.
A1 - Tamm, K.
A1 - Jänes, J.
A1 - Sikk, L.
A1 - Dusinska, M.
A1 - Longhin, E.
A1 - Rundén-Pran, E.
A1 - Mariussen, E.
A1 - El Yamani, N.
A1 - Unger, Wolfgang
A1 - Radnik, Jörg
A1 - Tropsha, A.
A1 - Cohen, Y.
A1 - Lesczynski, J.
A1 - Hendren, C. O.
A1 - Wiesner, M.
A1 - Winkler, D.
A1 - Suzuki, N.
A1 - Yoon, T. H.
A1 - Choi, J.-S.
A1 - Sanabria, N.
A1 - Gulumian, M.
A1 - Lynch, I.
T1 - NanoSolveIT Project: Driving nanoinformatics research to develop innovative and integrated tools for in silico nanosafety assessment
N2 - Nanotechnology has enabled the discovery of a multitude of novel materials exhibiting unique physicochemical (PChem) properties compared to their bulk analogues. These properties have led to a rapidly increasing range of commercial applications; this, however, may come at a cost, if an association to long-term health and environmental risks is discovered or even just perceived. Many nanomaterials (NMs) have not yet had their potential adverse biological effects fully assessed, due to costs and time constraints associated with the experimental assessment, frequently involving animals. Here, the available NM libraries are analyzed for their suitability for integration with novel nanoinformatics approaches and for the development of NM specific Integrated Approaches to Testing and Assessment (IATA) for human and environmental risk assessment, all within the NanoSolveIT cloud-platform. These established and well-characterized NM libraries (e.g. NanoMILE, NanoSolutions, NANoREG, NanoFASE, caLIBRAte, NanoTEST and the Nanomaterial Registry (>2000 NMs)) contain physicochemical characterization data as well as data for several relevant biological endpoints, assessed in part using harmonized Organisation for Economic Co-operation and Development (OECD) methods and test guidelines.
Integration of such extensive NM information sources with the latest nanoinformatics methods will allow NanoSolveIT to model the relationships between NM structure (morphology), properties and their adverse effects and to predict the effects of other NMs for which less data is available. The project specifically addresses the needs of regulatory agencies and industry to effectively and rapidly evaluate the exposure, NM hazard and risk from nanomaterials and nano-enabled products, enabling implementation of computational ‘safe-by-design’ approaches to facilitate NM commercialization.
KW - Nanoinformatics
KW - Hazard assessment
KW - (Quantitative) Structure-Active Relationships
KW - Safe-by-design
KW - Predictive modelling
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505952
DO - https://doi.org/10.1016/j.csbj.2020.02.023
VL - 18
SP - 583
EP - 602
PB - Elsevier B.V.
AN - OPUS4-50595
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Anja
A1 - Heinrich, Thomas
A1 - Tougaard, S.
A1 - Werner, W. S. M.
A1 - Hronek, M.
A1 - Kunz, Valentin
A1 - Radnik, Jörg
A1 - Stockmann, Jörg M.
A1 - Hodoroaba, Vasile-Dan
A1 - Benemann, Sigrid
A1 - Nirmalananthan-Budau, Nithiya
A1 - Geißler, Daniel
A1 - Sparnacci, K.
A1 - Unger, Wolfgang
T1 - Determining the thickness and completeness of the shell of polymer core-shell nanoparticles by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and transmission scanning electron microscopy
N2 - Core–shell nanoparticles (CSNPs) have become indispensable in various industrial applications. However, their real internal structure usually deviates from an ideal core–shell structure. To control how the particles perform with regard to their specific applications, characterization techniques are required that can distinguish an ideal from a nonideal morphology. In this work, we investigated poly(tetrafluoroethylene)–poly(methyl methacrylate) (PTFE–PMMA) and poly(tetrafluoroethylene)–polystyrene (PTFE–PS) polymer CSNPs with a constant core diameter (45 nm) but varying shell thicknesses (4–50 nm). As confirmed by transmission scanning electron microscopy (T-SEM), the shell completely covers the core for the PTFE–PMMA nanoparticles, while the encapsulation of the core by the shell material is incomplete for the PTFE–PS nanoparticles. X-ray photoelectron spectroscopy (XPS) was applied to determine the shell thickness of the nanoparticles. The software SESSA v2.0 was used to analyze the intensities of the elastic peaks, and the QUASES software package was employed to evaluate the shape of the inelastic background in the XPS survey spectra. For the first time, nanoparticle shell thicknesses are presented, which are exclusively based on the analysis of the XPS inelastic background. Furthermore, principal component analysis (PCA)-assisted time-of-flight secondary-ion mass spectrometry (ToF-SIMS) of the PTFE–PS nanoparticle sample set revealed a systematic variation among the samples and, thus, confirmed the incomplete encapsulation of the core by the shell material. As opposed to that, no variation is observed in the PCA score plots of the PTFE–PMMA nanoparticle sample set. Consequently, the complete coverage of the core by the shell material is proved by ToF-SIMS with a certainty that cannot be achieved by XPS and T-SEM.
KW - XPS
KW - T-SEM
KW - ToF-SIMS
KW - Core-shell nanoparticles
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-499165
DO - https://doi.org/10.1021/acs.jpcc.9b09258
VL - 123
IS - 49
SP - 29765
EP - 29775
PB - American Chemical Society
CY - Washington, DC
AN - OPUS4-49916
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Tu, Z.
A1 - Donskyi, Ievgen
A1 - Qiao, H.
A1 - Zhu, Z.
A1 - Unger, Wolfgang
A1 - Hackenberger, C. P. R.
A1 - Chen, W.
A1 - Adeli, M.
A1 - Haag, R.
T1 - Graphene Oxide-Cyclic R10 Peptide Nuclear Translocation Nanoplatforms for the Surmounting of Multiple-Drug Resistance
N2 - Multidrug resistance resulting from a variety of defensive pathways in Cancer has become a global concern with a considerable impact on the mortality associated with the failure of traditional chemotherapy. Therefore, further research and new therapies are required to overcome this challenge. In this work, a cyclic R10 peptide (cR10) is conjugated to polyglycerol-covered nanographene oxide to engineer a nanoplatform for the surmounting of multidrug resistance. The nuclear translocation of the nanoplatform, facilitated by cR10 peptide, and subsequently, a laser-triggered release of the loaded doxorubicin result in efficient anticancer activity confirmed by both in vitro and in vivo experiments. The synthesized nanoplatform with a combination of different features, including active nucleus-targeting, highloading capacity, controlled release of cargo, and photothermal property, provides a new strategy for circumventing multidrug resistant cancers.
KW - Graphen Oxide
KW - Nanoplatform
KW - Cancer
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510061
DO - https://doi.org/10.1002/adfm.202000933
VL - 30
IS - 35
SP - 2000933
PB - Wiley VCH
AN - OPUS4-51006
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stockmann, Jörg M.
A1 - Radnik, Jörg
A1 - Bütefisch, S.
A1 - Busch, I.
A1 - Weimann, T.
A1 - Passiu, C.
A1 - Rossi, A.
A1 - Unger, Wolfgang
T1 - A new test specimen for the determination of the field of view of small-area X-ray photoelectron spectrometers
N2 - Small-area/spot photoelectron spectroscopy (SAXPS) is a powerful tool for the investigation of small surface features like microstructures of electronic devices, sensors or other functional surfaces, and so forth. For evaluating the quality of such microstructures, it is often crucial to know whether a small signal in a spectrum is an unwanted contamination of the field of view (FoV), defined by the instrument settings, or it originated from outside. To address this issue, the d80/20 parameter of a line scan across a chemical edge is often used. However, the typical d80/20 parameter does not give information on contributions from the long tails of the X-ray beam intensity distribution or the electron-optical system as defined by apertures. In the VAMAS TWA2 A22 project “Applying planar, patterned, multi-metallic samples to assess the impact of analysis area in surface-chemical analysis,” new test specimen was developed and tested. The here presented testing material consists of a silicon wafer substrate with an Au-film and embedded Cr circular and square spots with decreasing dimensions from 200 μm down to 5 μm. The spot sizes are traceable to the length unit due to size measurements with a metrological SEM. For the evaluation of the FoV, we determined the Au4f intensities measured with the center of the FoV aligned with the center of the spot and normalized to the Au4f intensity determined on the Au-film. With this test specimen, it was possible to characterize, as an example, the FoV of a Kratos AXIS Ultra DLD XPS instrument.
T2 - ECASIA 2019
CY - Dresden, Germany
DA - 15.09.2019
KW - Field of view
KW - Reference material
KW - Selected area XPS
KW - Small-area XPS
KW - Small-spot XPS
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509902
DO - https://doi.org/10.1002/sia.6831
SN - 1096-9918
VL - 52
IS - 12
SP - 890
EP - 894
PB - John Wiley & Sons Ltd
AN - OPUS4-50990
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stroh, Julia
A1 - Ali, Naveed Zafar
A1 - Maierhofer, Christiane
A1 - Emmerling, Franziska
T1 - Ettringite via Mechanochemistry: A Green and Rapid Approach for Industrial Application
N2 - Here, we report on a first mechanochemical synthesis of ettringite, an important cement hydrate phase. The mineral compound ettringite ([Ca3Al(OH)6]2·(SO4)3·26H2O) occurs rarely in nature, but is common for cement-based materials. Ettringite has wide technical application in the ceramic and paper industry. However, its typical wet-chemical synthesis is cumbersome and produces waste water and CO2 emissions. Here, we investigate the first mechanochemical synthesis of ettringite for developing an easy and sustainable alternative for industrial application. The mechanosynthesis was monitored in situ by coupled synchrotron X-ray diffraction (XRD) and infrared thermography (IRT). The consumption of the reactants and the formation of the reaction product were monitored with time-resolved XRD. IRT showed the temperature increase based on the exothermic reaction. The reaction conversion was significantly improved changing the strategy of the mechanosynthesis from a one- to a two-step process. The latter included neat pregrinding of solid reactants followed by a delayed addition of the stoichiometric amount of water. Thus, an increase of reaction conversion from 34 to 94% of ettringite could be achieved.
KW - XRD
KW - Mechanochemistry
KW - Ettringite
KW - In situ
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-479016
DO - https://doi.org/10.1021/acsomega.9b00560
SN - 2470-1343
VL - 4
IS - 4
SP - 7734
EP - 7737
PB - ACS Publications
CY - Washington, DC
AN - OPUS4-47901
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 - Szymoniak, Paulina
A1 - Kolmangadi, Mohamed A.
A1 - Böhning, Martin
A1 - Frick, B.
A1 - Apple, M.
A1 - Mole, R. A.
A1 - De Souza, N. R.
A1 - Zorn, R.
A1 - Schönhals, Andreas
T1 - Confined Segmental Diffusion in Nanophase Separated Janus Polynorbornenes as Investigated by Quasielastic Neutron Scattering
N2 - A combination of neutron time-of-flight and neutron backscattering spectroscopy was used to investigate the molecular dynamics of Janus polynorbornenes (Janus poly(tricyclononenes)) on a microscopic level.
These Janus polynorbornenes, denoted as PTCNSiOR, have a semirigid backbone with −Si(OR)3 side groups attached to it. R represents the length of the alkyl side chain. Here side chain lengths of R = 3 (propyl) and R = 8 (octyl) were considered. It is worth mentioning that these polymers have some potential as active layers in gas separation membranes, especially for the separation of higher hydrocarbons. The combination of time-of-flight and backscattering will ensure a reasonably broad time window for analysis where the incoherent intermediate scattering function SInc(q,t) is considered. Previously, it was shown by X-ray investigations that the system undergoes a nanophase separation into alkyl side chain-rich domains surrounded by a backbone-rich matrix. For PTCNSiOPr (R = 3), the alkyl side-chain-rich domains are truly isolated in the backbone-rich matrix, whereas for PTCNSiOOc (R = 8) these domains percolate through the matrix. Further, it was also previously shown that the alkyl side-chain-rich domains undergo a glass transition. The advantage of neutron scattering experiments discussed here is that besides temporal also spatial information is obtained which will allow conclusions to be drawn about the type of molecular fluctuations. At the lowest measured temperature, the decay in Sinc(q,t) is due to the methyl group rotation. The methyl group dynamics is analyzed in terms of a modified jump-diffusion in a 3-fold potential and yields to a reasonable fraction of hydrogens which contribute to the methyl group rotation. At higher temperatures, the decay in SInc(q,t) is due to both the methyl group rotation and the segmental dynamics in the alkyl side-chain-rich domains. The segmental diffusion is modeled by a sublinear diffusion. For the analysis of the scattering function SInc(q,t) of PTCNSiOPr an elastic scattering due to the immobilized backbone-rich matrix must be taken into account. The analysis reveals that the segmental dynamics is confined by the finite size of alkyl chain-rich domains and that it is intrinsically heterogeneous in nature. Both effects are more pronounced for PTCNSiOPr in comparison to those of PTCNSiOOc.
KW - Polynorbornene
KW - Quasielastic Neutron Scattering
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608712
DO - https://doi.org/10.1021/acs.macromol.4c01045
SP - 1
EP - 14
PB - ACS Publications
AN - OPUS4-60871
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hülagü, Deniz
A1 - Tobias, Charlie
A1 - Dao, Radek
A1 - Komarov, Pavel
A1 - Rurack, Knut
A1 - Hodoroaba, Vasile-Dan
T1 - Towards 3D determination of the surface roughness of core–shell microparticles as a routine quality control procedure by scanning electron microscopy
N2 - AbstractRecently, we have developed an algorithm to quantitatively evaluate the roughness of spherical microparticles using scanning electron microscopy (SEM) images. The algorithm calculates the root-mean-squared profile roughness (RMS-RQ) of a single particle by analyzing the particle’s boundary. The information extracted from a single SEM image yields however only two-dimensional (2D) profile roughness data from the horizontal plane of a particle. The present study offers a practical procedure and the necessary software tools to gain quasi three-dimensional (3D) information from 2D particle contours recorded at different particle inclinations by tilting the sample (stage). This new approach was tested on a set of polystyrene core-iron oxide shell-silica shell particles as few micrometer-sized beads with different (tailored) surface roughness, providing the proof of principle that validates the applicability of the proposed method. SEM images of these particles were analyzed by the latest version of the developed algorithm, which allows to determine the analysis of particles in terms of roughness both within a batch and across the batches as a routine quality control procedure. A separate set of particles has been analyzed by atomic force microscopy (AFM) as a powerful complementary surface analysis technique integrated into SEM, and the roughness results have been compared.
KW - Core–shell particles
KW - Image analysis
KW - Roughness
KW - Scanning electron microscopy
KW - Atomic force microscopy
KW - Tilting
KW - Batch analysis
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607590
DO - https://doi.org/10.1038/s41598-024-68797-7
SN - 2045-2322
VL - 14
IS - 1
SP - 1
EP - 13
PB - Springer Science and Business Media LLC
AN - OPUS4-60759
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dobosy, Péter
A1 - Nguyen, Hoang Thi Phuong
A1 - Záray, Gyula
A1 - Streli, Christina
A1 - Ingerle, Dieter
A1 - Ziegler, Philipp
A1 - Radtke, Martin
A1 - Buzanich, Ana Guilherme
A1 - Endrédi, Anett
A1 - Fodor, Ferenc
T1 - Effect of iodine species on biofortification of iodine in cabbage plants cultivated in hydroponic cultures
N2 - Iodine is an essential trace element in the human diet because it is involved in the synthesis of thyroid hormones. Iodine deficiency affects over 2.2 billion people worldwide, making it a significant challenge to find plant-based sources of iodine that meet the recommended daily intake of this trace element. In this study, cabbage plants were cultivated in a hydroponic system containing iodine at concentrations ranging from 0.01 to 1.0 mg/L in the form of potassium iodide or potassium iodate. During the experiments, plant physiological parameters, biomass production, and concentration changes of iodine and selected microelements in different plant parts were investigated. In addition, the oxidation state of the accumulated iodine in root samples was determined. Results showed that iodine addition had no effect on photosynthetic efficiency and chlorophyll content. Iodide treatment did not considerably stimulate biomass production but iodate treatment increased it at concentrations less than 0.5 mg/L. Increasing iodine concentrations in the nutrient solutions increased iodine content in all plant parts; however, the iodide treatment was 2–7 times more efficient than the iodate treatment. It was concluded, that iodide addition was more favourable on the target element accumulation, however, it should be highlighted that application of this chemical form in nutrient solution decreased the concetrations of selected micoelement concentration comparing with the control plants. It was established that iodate was reduced to iodide during its uptake in cabbage roots, which means that independently from the oxidation number of iodine (+ 5, − 1) applied in the nutrient solutions, the reduced form of target element was transported to the aerial and edible tissues.
KW - BAMline
KW - XANES
KW - Synchrotron
KW - Lodine
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608330
DO - https://doi.org/10.1038/s41598-024-66575-z
VL - 14
IS - 1
SP - 1
EP - 12
PB - Springer Science and Business Media LLC
AN - OPUS4-60833
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Huang, Junhao
A1 - Klahn, Marcus
A1 - Tian, Xinxin
A1 - Bartling, Stephan
A1 - Zimina, Anna
A1 - Radtke, Martin
A1 - Rockstroh, Nils
A1 - Naliwajko, Pawel
A1 - Steinfeldt, Norbert
A1 - Peppel, Tim
A1 - Grunwaldt, Jan‐Dierk
A1 - Logsdail, Andrew J.
A1 - Jiao, Haijun
A1 - Strunk, Jennifer
T1 - Fundamental Structural and Electronic Understanding of Palladium Catalysts on Nitride and Oxide Supports
N2 - The nature of the support can fundamentally affect the function of a heterogeneous catalyst. For the novel type of isolated metal atom catalysts, sometimes referred to as single‐atom catalysts, systematic correlations are still rare. Here, we report a general finding that Pd on nitride supports (non‐metal and metal nitride) features a higher oxidation state compared to that on oxide supports (non‐metal and metal oxide). Through thorough oxidation state investigations by X‐ray absorption spectroscopy (XAS), X‐ray photoelectron spectroscopy (XPS), CO‐DRIFTS, and density functional theory (DFT) coupled with Bader charge analysis, it is found that Pd atoms prefer to interact with surface hydroxyl group to form a Pd(OH)x species on oxide supports, while on nitride supports, Pd atoms incorporate into the surface structure in the form of Pd−N bonds. Moreover, a correlation was built between the formal oxidation state and computational Bader charge, based on the periodic trend in electronegativity.
KW - BAmline
KW - XANES
KW - Catalyst
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608341
DO - https://doi.org/10.1002/anie.202400174
SN - 1433-7851
VL - 63
IS - 20
SP - 1
EP - 9
PB - Wiley
AN - OPUS4-60834
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Senges, Gene
A1 - Buzanich, Ana Guilherme
A1 - Lindič, Tilen
A1 - Gully, Tyler A.
A1 - Winter, Marlon
A1 - Radtke, Martin
A1 - Röder, Bettina
A1 - Steinhauer, Simon
A1 - Paulus, Beate
A1 - Emmerling, Franziska
A1 - Riedel, Sebastian
T1 - Unravelling highly oxidized nickel centers in the anodic black film formed during the Simons process by in situ X-ray absorption near edge structure spectroscopy
N2 - The electrofluorination after Simons has been used for the last century to produce everyday life materials. An in situ XANES investigation of the controversially debated black film apparent in the Simons process revealed high-valent nickel centers.
KW - Synchrotron
KW - BAMline
KW - XANES
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608366
DO - https://doi.org/10.1039/d3sc06081k
SN - 2041-6520
VL - 15
IS - 12
SP - 4504
EP - 4509
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60836
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Omar, Hassan
A1 - Ahamadi, Shayan
A1 - Hülagü, Deniz
A1 - Hidde, Gundula
A1 - Hertwig, Andreas
A1 - Szymoniak, Paulina
A1 - Schönhals, Andreas
T1 - Investigations of the adsorbed layer of polysulfone: Influence of the thickness of the adsorbed layer on the glass transition of thin films
N2 - This work studies the influence of the adsorbed layer on the glass transition of thin films of polysulfone. Therefore, the growth kinetics of the irreversibly adsorbed layer of polysulfone on silicon substrates was first investigated using the solvent leaching approach, and the thickness of the remaining layer was measured with atomic force microscopy. Annealing conditions before leaching were varied in temperature and time (0–336 h). The growth kinetics showed three distinct regions: a pre-growth step where it was assumed that phenyl rings align parallel to the substrate at the shortest annealing times, a linear growth region, and a crossover from linear to logarithmic growth observed at higher temperatures for the longest annealing times. No signs of desorption were observed, pointing to the formation of a strongly adsorbed layer.
Second, the glass transition of thin polysulfone films was studied in dependence on the film thickness using spectroscopic ellipsometry. Three annealing conditions were compared: two with only a tightly bound layer formed in the linear growth regime and one with both tightly bound and loosely adsorbed layers formed in the logarithmic growth regime. The onset thickness and increase in the glass transition temperature increases with annealing time and temperature. These differences were attributed to the distinct conformations of the formed adsorbed layers.
KW - Glass transition
KW - Adsorbed Layer
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607701
DO - https://doi.org/10.1063/5.0223415
SN - 0021-9606
VL - 161
IS - 5
SP - 1
EP - 12
PB - AIP Publishing
AN - OPUS4-60770
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Kai
A1 - Mirabella, Francesca
A1 - Knigge, Xenia
A1 - Mezera, Marek
A1 - Weise, Matthias
A1 - Sahre, Mario
A1 - Wasmuth, Karsten
A1 - Voss, Heike
A1 - Hertwig, Andreas
A1 - Krüger, Jörg
A1 - Radnik, Jörg
A1 - Hodoroaba, Vasile-Dan
A1 - Bonse, Jörn
T1 - Chemical and topographical changes upon sub-100-nm laser-induced periodic surface structure formation on titanium alloy: the influence of laser pulse repetition rate and number of over-scans
N2 - Titanium and its alloys are known to allow the straightforward laser-based manufacturing of ordered surface nanostructures, so-called high spatial frequency laser-induced periodic surface structures (HSFL). These structures exhibit sub-100 nm spatial periods – far below the optical diffraction limit. The resulting surface functionalities are usually enabled by both, topographic and chemical alterations of the nanostructured surfaces. For exploring these effects, multi-method characterizations were performed here for HSFL processed on Ti–6Al–4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm, ≈1 ps pulse duration, 1–400 kHz) under different laser scan processing conditions, i.e., by systematically varying the pulse repetition frequency and the number of laser irradiation passes. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), tactile stylus profilometry, as well as near-surface chemical analyses hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (ToF-SIMS). This provides a quantification of the laser ablation depth, the geometrical HSFL characteristics and enables new insights into the depth extent and the nature of the non-ablative laser-induced near-surface oxidation accompanying these nanostructures. This allows to answer the questions how the processing of HSFL can be industrially scaled up, and whether the latter is limited by heat-accumulation effects.
T2 - 2023 E-MRS Spring Meeting, Symposium L "Making light matter: lasers in material sciences and photonics"
CY - Strasbourg, France
DA - 29.05.2023
KW - Laser-induced periodic surface structures (LIPSS)
KW - Ultrashort laser pulses
KW - Laser processing
KW - Hard X-ray photoelectron spectroscopy (HAXPES)
KW - Time-of-flight secondary ion mass spectrometry (ToF-SIMS)
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-589902
UR - https://onlinelibrary.wiley.com/doi/full/10.1002/pssa.202300719
DO - https://doi.org/10.1002/pssa.202300719
SN - 1862-6319
VL - 221
IS - 15
SP - 1
EP - 12
PB - Wiley-VCH GmbH
CY - Weinheim
AN - OPUS4-58990
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - About alcohol-initiated polymerization of glycolide and separate crystallization of cyclic and linear polyglycolides
N2 - Alcohol-initiated polymerizations of glycolide (GL) catalyzed by tin(II) 2-ethylhexanoate (SnOct2) were carried out in bulk with variation of GA/In ratio, temperature and time. Due to a rather strong competition of cyclization polyglycolide (PGA) free of cycles were never obtained. When the cyclic catalysts 2,2-dibutal-2-stanna − 1,3-dithiolane (DSTL) or 2-stanna 1,3-dioxo-4,5,6,7 bibenzepane (SnBiph) were used in combination with 1,4-butanediol the influence of cyclization was even stronger. Furthermore, the degrees of polymerization were higher than the GA/alcohol ratio due to rapid polycondensation in the solid state. At 160 °C or below, the matrixassisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra indicated separate crystallization of low molar mass cyclic and linear PGAs from the same reaction mixture (also observed for poly(L-lactide)s).
KW - MALDI TOF MS
KW - Polyglycolide
KW - Ring opening polymerization
KW - Cyclization
KW - Crystallization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607282
DO - https://doi.org/10.1016/j.polymer.2024.127440
SN - 0032-3861
VL - 309
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-60728
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ghata, Anupama
A1 - Bernges, Tim
A1 - Maus, Oliver
A1 - Wankmiller, Björn
A1 - Naik, Aakash Ashok
A1 - Bustamante, Joana
A1 - Gaultois, Michael W.
A1 - Delaire, Olivier
A1 - Hansen, Michael Ryan
A1 - George, Janine
A1 - Zeier, Wolfgang G.
T1 - Exploring the Thermal and Ionic Transport of Cu+ Conducting Argyrodite Cu7PSe6
N2 - AbstractUnderstanding the origin of low thermal conductivities in ionic conductors is essential for improving their thermoelectric efficiency, although accompanying high ionic conduction may present challenges for maintaining thermoelectric device integrity. This study investigates the thermal and ionic transport in Cu7PSe6, aiming to elucidate their fundamental origins and correlation with the structural and dynamic properties. Through a comprehensive approach including various characterization techniques and computational analyses, it is demonstrated that the low thermal conductivity in Cu7PSe6 arises from structural complexity, variations in bond strengths, and high lattice anharmonicity, leading to pronounced diffuson transport of heat and fast ionic conduction. It is found that upon increasing the temperature, the ionic conductivity increases significantly in Cu7PSe6, whereas the thermal conductivity remains nearly constant, revealing no direct correlation between ionic and thermal transport. This absence of direct influence suggests innovative design strategies in thermoelectric applications to enhance stability by diminishing ionic conduction, while maintaining low thermal conductivity, thereby linking the domains of solid‐state ionics and thermoelectrics. Thus, this study attempts to clarify the fundamental principles governing thermal and ionic transport in Cu+‐superionic conductors, similar to recent findings in Ag+ argyrodites.
KW - Thermoelectrics
KW - Phonons
KW - Chemically Complex Materials
KW - DFT
KW - Bonding Analysis
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608866
DO - https://doi.org/10.1002/aenm.202402039
SP - 1
EP - 9
PB - Wiley
AN - OPUS4-60886
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Casali, Lucia
A1 - Carta, Maria
A1 - Michalchuk, Adam A. L.
A1 - Delogu, Francesco
A1 - Emmerling, Franziska
T1 - Kinetics of the mechanically induced ibuprofen–nicotinamide co-crystal formation by in situ X-ray diffraction
N2 - Mechanochemistry is drawing attention from the pharmaceutical industry given its potential for sustainable material synthesis and manufacture. Scaling mechanochemical processes to industrial level remains a challenge due to an incomplete understanding of their underlying mechanisms. We here show how time-resolved in situ powder X-ray diffraction data, coupled with analytical kinetic modelling, provides a powerful approach to gain mechanistic insight into mechanochemical reactions. By using the ibuprofen–nicotinamide co-crystal mechanosynthesis as a benchmark system, we investigate the behaviour of the solids involved and identify the factors that promote the reaction. As mechanochemical mechanisms become increasingly clear, it promises to become a breakthrough in the industrial preparation of advanced pharmaceuticals.
KW - Mechanochemistry
KW - Kinetics
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608820
DO - https://doi.org/10.1039/D4CP01457J
SN - 1463-9084
VL - 26
SP - 22041
EP - 22048
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60882
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - Syntheses of high molecular mass polyglycolides via ring-opening polymerization with simultaneous polycondensation(ROPPOC) by means of tin and zinc catalysts
N2 - Glycolide was polymerized in bulk by means of four different ROPPOC catalysts: tin(II) 2-ethylhexanoate (SnOct2), dibutyltin bis(pentafluoro-phenoxide) (BuSnOPF),zinc biscaproate (ZnCap), and zinc bis(pentafluoro-phenyl sulfide) (ZnSPF). The temperature was varied between 110 and 180°C and the time between 3 h and 7 days. For the few polyglycolides (PGAs) that were soluble extremely high molecular masses were obtained. The MALDI TOF mass spectra had all a low signal-to-noise ration and displayed the peaks of cyclic PGAs with a“saw-tooth pattern ”indicating formation of extended-ring crystallites in the mass range below m/z 2500. The shape of DSC curves varied considerably with catalyst and reaction conditions, whereas the long-distance values measured by SAXS were small and varied little with the polymeriza-tion conditions.
KW - MALDI TOF MS
KW - Polyglycolide
KW - Crystalinity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598221
DO - https://doi.org/10.1002/pat.6365
VL - 35
IS - 4
SP - 1
EP - 10
PB - John Wiley & Sons Ltd.
AN - OPUS4-59822
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -