TY - CONF A1 - Florian, Camilo T1 - Femtosecond laser-induced oxidation in the formation of periodic surface structures N2 - Laser-induced oxide graded layers may contribute to the formation of a new type of embedded low-spatial frequency LIPSS with an anomalous orientation parallel to the laser polarization. In this contribution, we explore this effect experimentally with femtosecond laser pulses and numerically by finite-difference time-domain (FDTD) calculations. T2 - 2021 Conference on Lasers and Electro-Optics/Europe – European Quantum Electronics Virtual Conferences CY - Online meeting DA - 21.06.2021 KW - Laser-induced periodic surface structures (LIPSS) KW - Surface oxidation KW - Femtosecond laser ablation KW - Finite-difference time-domain calculations PY - 2021 AN - OPUS4-52859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra T1 - Sample Preparation of Nano-Powders for Particle Size Determination N2 - The use of increasingly finer starting powders up to nanopowders can also be observed in the field of ceramics. Their advantages consist, for example, in their lower activation energy, an increase in strength or unique optical properties. However, handling and characterization of the powders are much more difficult. The main reason for this is the very high adhesive forces between the particles and between particles and other surfaces, too. Therefore, submicron and even more so nanoparticles tend to agglomerate and their separation into primary particles during sample preparation prior to particle sizing is of particular challenge. A representative measurement sample is only obtained when it no longer contains agglomerates. The evaluation of the dispersion process and a decision on whether it was successful thus increases in importance for the reliability of the measurement results of particle sizing. The presentation uses examples to show possible approaches and provides information on possible sources of error. It is shown that successful granulometric characterisation of fine powders requires both an improved dispersion technique and very often an effective combination of two or more measurement methods. T2 - 96. Jahrestagung der Deutschen Keramischen Gesellschaft CY - Online Meeting DA - 19.04.2021 KW - Agglomerates KW - Nano-powder KW - Dispersion process PY - 2021 AN - OPUS4-52503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fiedler, Saskia T1 - Giant photon bunching of WS2 monolayer in cathodoluminescence N2 - Cathodoluminescence (CL) spectroscopy has become a powerful tool to study nanostructures due to its high spectral and spatial resolution down to sub-nanometer. More recently, CL technique has also been used for second order auto-correlation measurements (g(2)(t)) to identify different single photon emitters and photon bunching in different materials [1-2]. In this work, tungsten disulfide (WS2) monolayers encapsulated in hexagonal boron nitride (hBN) with and without monocrystalline Au nanodisks (NDs) have been studied, using CL and PL spectroscopy as well as g(2)-CL- and PL-measurements. CL and PL maps of different WS2 monolayers before/after Au ND deposition show a narrow peak at ~625 nm without any background emission. In CL, the hBN not only protects WS2 from the electron beam but also acts as a charge carrier sink which substantially increases the CL signal [3]. A further CL enhancement is achieved by Au ND deposition, exhibiting the maximum at the center of the NDs without any size dependence. The PL intensity is unaffected. This indicates that Purcell enhancement cannot be the underlying mechanism. Furthermore, a giant CL-photon bunching of the hBN-encapsulated WS2 monolayers is found which is independent of the applied voltage but highly dependent on the electron beam current. At the lowest current of ~2 pA, a CL bunching factor of up to 160 is observed. Varying thicknesses of the surrounding hBN increases the overall CL signal but does not affect the bunching factor, though it exhibits small local changes within the same flake. In contrast, there is no PL correlation (g(2)(0) = 1). Interestingly, this photon bunching can be further increased by Au NDs, resulting in the highest ever observed bunching factor of close to 2200. Once again, this enhancement is independent of the Au ND’s diameter although some disks show higher bunching factors than others. Most likely, the Au acts as shield for the incoming primary electrons, resulting in an even further decreased current, and thereby, increased bunching. In conclusion, large CL-photon bunching is found in hBN-encapsulated WS2 monolayers which can be substantially enhanced by Au NDs. References [1] M.A. Feldmann, E.F. Demitrescu, D. Bridges, M.F. Chisholm, R.B. Davidson, P.G. Evans, J.A. Hachtel, A. Hu, R.C. Pooser, R.F. Haglund, B.J. Lawrie, Phys. Rev. B, 97, 081404(R) (2018) [2] S. Meuret, L.H.G. Tizei, T. Cazimajou, R. Bourrellier, H.C. Chang, F. Treussartm M. Kociak, Phys. Rev. Letter, 114, 197401 (2015) [3] S. Zheng, J.-K. So, F. Liu, Z. Liu, N. Zheludev, H.J. Fan, Nano Lett., 17, 6475-6480 (2017) T2 - GSELOP2021 CY - Paris, France DA - 23.08.2021 KW - Cathodoluminescence KW - Photon bunching KW - 2D materials KW - TMDCs KW - Au nanodisks KW - Transition metal dichalcogenide KW - Au nanoparticles PY - 2021 AN - OPUS4-53153 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Florian, Camilo T1 - Silicon surface amorphization and re-crystallization via single femtosecond laser pulses N2 - Silicon is the material responsible for most of the technological developments during the past century, making it one of the most studied materials along different disciplines. However, there are still unturned stones regarding its superficial re-solidification after femtosecond laser-induced local melting. In this presentation, we report irradiation experiments with single femtosecond pulses (790 nm, 30 fs) with a spatially Gaussian distribution on two different types of silicon with orientations <111> and <100>. The surface modifications were studied in detail via different techniques, including optical microscopy, atomic force microscopy, spectroscopic imaging ellipsometry, energy dispersive X-ray spectroscopy and high-resolution transmission electron microscopy. We quantitatively estimate the resulting radial amorphous layer depth profiles with maximum thicknesses around some tenths of nanometers for fluences in between the melting and ablation thresholds. In particular, spectroscopic imaging ellipsometry (SIE) allowed fast data acquisition using multiple wavelengths to provide experimental measurements for calculating the nanometric radial amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. SIE proved to be capable of detecting and measuring nanometric structural and chemical modifications (oxidation) on the studied laser spots. The accuracy of the SIE-based calculations is verified experimentally by characterizing an in-depth material lamella via high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). For completeness, we present a mathematical modelling for the melt layer thickness considering different optical absorption processes including one photon absorption, two photon absorption and free-carrier absorption, highlighting the relevance of the latter one in the femtosecond laser-induced melting of silicon. T2 - 28th International Conference on Advanced Laser Technologies (ALT'21) CY - Online meeting DA - 06.09.2021 KW - Silicon KW - Femtosecond laser KW - Phase transitions KW - Spectroscopic imaging ellipsometry KW - Transmission electron microscopy PY - 2021 AN - OPUS4-53235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Hiid, Gundula A1 - Szymoniak, Paulina A1 - Hertwig, Andreas A1 - Schönhals, Andreas T1 - Growth kinetics of the adsorbed layer of poly(bisphenol A carbonate) and its effect on the glass transition behavior in thin films N2 - The glass transition behavior of thin films of poly(bisphenol A carbonate) (PBAC) was studied employing ellipsometry. The glass transition temperature increases with the reduction of the film thickness. This result is attributed to the formation of an adsorbed layer with a reduced mobility compared to bulk PBAC. Therefore, for the first time, the growth kinetics of the adsorbed layer of PBAC was investigated, prepared by leaching samples from a 200 nm thin film which were annealed for several times at three different temperatures. The thickness of each prepared adsorbed layer was measured by multiple scans using atomic force microscopy (AFM). Additionally, an unannealed sample was measured. Comparison of the measurements of the unannealed and the annealed samples provides proof of a pre-growth regime for all annealing temperatures which was not observed for other polymers. For the lowest annealing temperature after the pre-growth stage only a growth regime with a linear time dependence is observed. For higher annealing temperatures the growth kinetics changes from a linear to a logarithmic growth regime at a critical time. At the longest annealing times the films showed signs of dewetting where segments of the adsorbed film were removed from the substrate (dewetting by desorption). The dependence of the surface roughness of the PBAC surface on annealing time also confirmed that the films annealed at highest temperatures for the longest times desorbed from the substrate. KW - Ultra thin polymer films PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574531 DO - https://doi.org/10.1039/D3RA02020G SN - 2046-2069 VL - 13 IS - 21 SP - 14473 EP - 14483 PB - RSC Publishing CY - London AN - OPUS4-57453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritzsche, Sven A1 - Pauw, Brian Richard A1 - Weimann, Christiane A1 - Sturm, Heinz T1 - First of its kind: A test artifact for direct laser writing N2 - With femtosecond-laser direct writing (fs-LDW) maturing in all aspects as a manufacturing technology, a toolset for quality assurance must be developed. In this work we introduce a first of its kind test artifact. Test artifacts are standardized 3D models with specific geometric features to evaluate the performance of writing parameters. Test artifacts are already common in other 3D additive manufacturing technologies e.g. selective laser melting. The test artifact introduced in this work was developed in particular to accommodate the high geometrical resolution of fs-LDW structures and the limited possibilities to examine the resulting structure. Geometric accuracy, surface adhesion as well as confocal Raman spectroscopy results were considered when evaluating the design of the test artifact. We will explain the individual features and design considerations of our fs-LDW test artifact. The difference between two slicers, Cura and 3DPoli, and the implications on measured feature sizes and the general shape is quantified. The measured geometries are used to derive a general design guide for a specific combination of photoresists, laser power and scanning speed and to analyze the geometric accuracy of a structure produced using these guidelines. The shown test artifact is publicly available as STL file on GitHub (https://github.com/BAMresearch/2PP-TestArtifact) and in the supplement. KW - Laser direct writing KW - Multi photon lithography KW - Reference material KW - Raman spectroscopy KW - Confocal raman imaging KW - Slicers KW - Open data on zenodo PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580951 DO - https://doi.org/10.1088/1361-6501/acc47a VL - 34 IS - 7 SP - 1 EP - 14 PB - IOP Science AN - OPUS4-58095 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fiedler, Saskia A1 - Ton-That, C. A1 - Phillips, M. R. T1 - Defect-free ZnO nanorods with high angular distribution for enhanced excitonic emission N2 - AbstractLow-temperature hydrothermal growth has emerged as a popular method for the fabrication of ZnO nanorods (NRs), increasing the functionality and utility of ZnO-based devices. In this work, we study the influence of growth time, temperature and seed layer on the dimensions and angular distribution of ZnO NRs. High-quality NRs with a crisscrossed 60° angular distribution have been grown with a 20–60 nm diameter and 600 nm length. We show that, within the ideal range of growth parameters, the growth time and temperature have no controllable influence on NR diameter and length, while the deposition method and size of the pre-growth deposited ZnO seeds affects diameter and NR angular alignment. We demonstrate advantages of using crisscross-aligned NRs over planar ZnO for the enhancement of ZnO excitonic emission by optical coupling with gold nanoparticles. These results can be readily adapted for applications that involve surface coating-mediated enhancement of both light emission and injection. KW - ZnO nanorod KW - Hydrothermal growth KW - Seed layer KW - Angular distribution KW - Cathodoluminescence KW - Luminescence enhancement PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618176 DO - https://doi.org/10.1557/s43578-023-00941-x SN - 0884-2914 SN - 2044-5326 VL - 38 IS - 8 SP - 2145 EP - 2155 PB - Springer CY - Berlin AN - OPUS4-61817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schardt, Annika A1 - Schmitt, Johannes A1 - Engelhard, Carsten T1 - Single particle inductively coupled plasma mass spectrometry with nanosecond time resolution N2 - In this proof-of-principle study, we present our contribution to single particle inductively coupled plasma mass spectrometry (spICP-MS) developments with a novel in-house built data acquisition system with nanosecond time resolution (nanoDAQ) and a matching data processing approach. The new system can continuously sample the secondary electron multiplier (SEM) detector signal and enables the detection of gold nanoparticles (AuNP) as small as 7.5 nm with the commercial single quadrupole ICP-MS instrument used in this study. Recording of the SEM signal by the nanoDAQ is performed with a dwell time of approximately 4 ns. A tailored method was developed to process this type of transient data, which is based on determining the temporal distance between detector events that is denoted as event gap (EG). We found that the inverse logarithm of EG is proportional to the particle size and that the number of detector events corresponding to a particle signal distribution can be used to calibrate and determine the particle number concentration (PNC) of a nanoparticle dispersion. Due to the high data acquisition frequency, a statistically significant number of data points can be obtained in 60 s or less and the main time limitation for analyses is merely the sample uptake time and rinsing step between analyte solutions. At this stage, the data processing method provides average information on complete data sets only and will be adapted to enable particle-by-particle analysis with future hardware/software revision. KW - ICP-MS KW - Nanoparticles KW - Nanosecond time resolution KW - Single particle detection PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612706 DO - https://doi.org/10.1039/d3ja00373f SN - 1364-5544 SN - 0267-9477 VL - 39 IS - 2 SP - 389 EP - 400 PB - Royal Society of Chemistry (RSC) CY - Cambridge AN - OPUS4-61270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mezera, Marek A1 - Alamri, S. A1 - Hendriks, W. A. P. M. A1 - Hertwig, Andreas A1 - Elert, Anna Maria A1 - Bonse, Jörn A1 - Kunze, T. A1 - Lasagni, A. F. A1 - Römer, G. R. B. E. T1 - Hierarchical micro-/nano-structures on polycarbonate via UV pulsed laser processing N2 - Hierarchical micro/-nanostructures were produced on polycarbonate polymer surfaces by employing a two-step UV-laser processing strategy based on the combination of Direct Laser Interference Patterning (DLIP) of gratings and pillars on the microscale (3 ns, 266 nm, 2 kHz) and subsequently superimposing Laser-induced Periodic Surface Structures (LIPSS; 7–10 ps, 350 nm, 100 kHz) which adds nanoscale surface features. Particular emphasis was laid on the influence of the direction of the laser beam polarization on the morphology of resulting hierarchical surfaces. Scanning electron and atomic force microscopy methods were used for the characterization of the hybrid surface structures. Finite-difference time-domain (FDTD) calculations of the laser intensity distribution on the DLIP structures allowed to address the specific polarization dependence of the LIPSS formation observed in the second processing step. Complementary chemical analyzes by micro-Raman spectroscopy and attenuated total reflection Fourier-transform infrared spectroscopy provided in-depth information on the chemical and structural material modifications and material degradation imposed by the laser processing. It was found that when the linear laser polarization was set perpendicular to the DLIP ridges, LIPSS could be formed on top of various DLIP structures. FDTD calculations showed enhanced optical intensity at the topographic maxima, which can explain the dependency of the morphology of LIPSS on the polarization with respect to the orientation of the DLIP structures. It was also found that the degradation of the polymer was enhanced for increasing accumulated fluence levels. KW - Direct laser interference patterning KW - Laser-induced periodic surface structures (LIPSS) KW - Polycarbonate KW - Hierarchical structures KW - Surface functionalization PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509101 DO - https://doi.org/10.3390/nano10061184 SN - 2079-4991 VL - 10(6) IS - Special issue "Laser-generated periodic nanostructures" SP - 1184-1 EP - 1184-19 PB - MDPI CY - Basel AN - OPUS4-50910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fosodeder, P. A1 - Baumgartner, W. A1 - Steinwender, C. A1 - Hassel, A. W. A1 - Florian, Camilo A1 - Bonse, Jörn A1 - Heitz, J. T1 - Repellent rings at titanium cylinders against overgrowth by fibroblasts N2 - The invention of new miniaturized and smart medical implants continues in all medical fields, including miniaturized heart pacemakers. These implants often come with a titanium (Ti) casing, which may have to be removed after several months or years and shall therefore not be completely overgrown by cells or scar tissue after implantation. Scar tissue is mainly formed by fibroblast cells and extracellular matrix proteins like collagen produced by them. Suppression of fibroblast growth at Ti surfaces could be achieved by 800 nm femtosecond laser-ablation creating self-organized sharp spikes with dimensions in the 10 μm-range which are superposed by fine sub-μm parallel ripples. On flat Ti control samples, the best results regarding suppression of cell growth were obtained on spike-structures which were additionally electrochemically anodized under acidic conditions. When Ti cylinders with a diameter of 8 mm (similar as the pacemakers) were placed upright in a culture of murine fibroblasts, a multi-layer cell growth up to a height of at least 1.5 mm occurred within 19–22 days. We have demonstrated that a laser-structured and anodized ring around the Ti cylinder surface is an effective way to create a barrier that murine fibroblasts were not able to overgrow within this time. KW - Cell-repellent surfaces KW - Femtosecond laser-processing KW - Electrochemical treatment KW - Laser-induced micro- and nanostructures KW - Medical implants PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509966 DO - https://doi.org/10.1515/aot-2019-0070 SN - 2193-8576 SN - 2193-8584 VL - 9 IS - 3 (Topical issue: Laser micro- and nano-material processing - Part 2) SP - 113 EP - 120 PB - De Gruyter CY - Berlin AN - OPUS4-50996 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Laser-induced Periodic Surface Structures - Mechanisms, Applications, and unsolved Problems N2 - Laser-induced Periodic Surface Structures (LIPSS, ripples) are a universal phenomenon and can be generated in a contactless, single-step process on almost any type of solid upon irradiation with intense laser pulses. They represent a (quasi-)periodic modulation of the surface topography in the form of a linear grating and are typically formed in a “self-ordered” way in the focus of a laser beam. Thus, they are often accompanying laser material processing applications. The structural sizes of LIPSS typically range from several micrometers down to less than 100 nanometers – far beyond the optical diffraction limit – while their orientations exhibit a clear correlation with the local polarization direction of the laser radiation. From a theoretical point of view, a controversial debate has emerged during the last decades, whether LIPSS originate from electromagnetic effects (seeded already during the laser irradiation) – or whether they emerge from matter-reorganization processes (distinctly after the laser irradiation). From a practical point of view, however, LIPSS represent a simple and robust way for the nanostructuring of solids that allows creating a wide range of different surface functionalities featuring applications in optics, tribology, medicine, energy technologies, etc. While the currently available laser and scanner technology already allows surface processing rates at the m^2/min level, industrial applications of LIPSS are sometimes limited by the complex interplay between the nanoscale surface topography and the specific surface chemistry. This typically manifests in difficulties to control the processing of LIPSS and in limitations to ensure the long-term stability of the created surface functions. This presentation reviews the currently existent theories of LIPSS. A focus is laid on the historic development of the fundamental ideas behind the LIPSS, their corresponding mathematical descriptions and numerical implementations, along with a comparison and critical assessment of the different approaches. Moreover, some unsolved scientific problems related to LIPSS are identified and the pending technological limitations are discussed. Hereby, it is intended to stimulate further research and developments in the field of LIPSS for overcoming these limitations and for supporting the transfer of the LIPSS technology into industry. T2 - SPIG 2022 - 31st Summer School and International Symposium on the Physics of Ionized Gases CY - Belgrade, Serbia DA - 05.09.2022 KW - Laser-induced periodic surface structures (LIPSS) KW - Surface functionalization KW - Femtosecond laser processing PY - 2022 AN - OPUS4-55813 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas T1 - ELENA: a European project for electrical nanoscale metrology in industry N2 - A competitive advantage in the semiconductors industry is gained through the exploitation of new materials and processes, translating into improved components’ performances. This requires a metrological infrastructure allowing reliable nanoscale characterisation of new materials and devices, particularly in terms of their electrical parameters and properties. Traceability and reliability of nanoscale measurements stand as a major challenge for electrical properties (i.e. resistance, impedance) using conductive atomic force microscopy (C-AFM) and scanning microwave microscopy (SMM) techniques. The non-destructive analysis nature of these two methods is of paramount importance for the characterization of devices and components. However, the state of the art still lacks established measurement protocols, easy to use reference standards, well-defined best practice guides and easy to use 3D models to assess environmental and external stimulation effects. Moreover, costly instrumentation, particularly for high-frequency measurements, still hinders efficient advancements in these directions. ELENA is a 3-years European project that aims at bringing solutions to the aforementioned difficulties. To achieve this goal, the project uses a combination of nanoscale electrodynamic scanning probe methods in combination with optical tools such as spectroscopic ellipsometry on several lateral length scales to determine the electrical properties of layers and small structures. T2 - ICSE-9: The 9th International Conference on Spectroscopic Ellipsometry CY - Beijing, China DA - 2022-05-21 KW - Imaging Ellipsometry KW - Electrical thin layers KW - Scanning Probe methods KW - Hybrid metrology PY - 2022 AN - OPUS4-55464 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schardt, Annika A1 - Schmitt, Johannes A1 - Engelhard, Carsten T1 - Cover image for the article "Single particle inductively coupled plasma mass spectrometry with nanosecond time resolution" N2 - Image for the front cover of the issue 39(2) of the JAAS (Journal of Analytical Atomic Spectrometry). See Annika Schardt et al., pp. 389–400. Image reproduced by permission of Annika Schardt, Johannes Schmitt and Carsten Engelhard. KW - Analytical chemistry KW - Nanoparticles KW - Single-particle characterization KW - Instrumentation KW - spICP-MS PY - 2024 DO - https://doi.org/10.1039/D4JA90005G SN - 1364-5544 SN - 0267-9477 VL - 39 IS - 2 SP - 295 PB - Royal Society of Chemistry (RSC) CY - Cambridge AN - OPUS4-62156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuhlbusch, T. T1 - Size matters! - Auf dem Weg zu einer neuen OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien _ Projektteil BAuA N2 - Vorstellung der Ergebnisse bei der Entwicklung einer neuen OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien. (Projektteil Fasern.) Ergebnisse: Abweichungen zwischen SEM and TEM insbesondere bei langen Fasern Die Anwendung von TEM auf kurze Fasern < 5 µm beschränkt Für SEM wurde keine signifikante Abhängigkeit der Bestimmung der Faserdurchmesser von der Pixelgröße der Aufnahmen festgestellt Für TEM wurde eine Abhängigkeit der Bestimmung der Faserdurchmesser von der Pixelgröße festgestellt Der Einfluss der Bildauswertenden auf die Varianz der Ergebnisse ist klein im Vergleich zu der gesamten Varianz. Nanofasern können mit TEM und SEM bestimmt werden! T2 - Fachseminar des Umweltbundesamtes CY - Online meeting DA - 14.04.2021 KW - Nano KW - Nanofasern KW - OECD KW - Prüfrichtlinie KW - Nanomaterial PY - 2021 AN - OPUS4-53824 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuhlbusch, T. T1 - OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien - Projektteil Fasern N2 - Abschlusspräsentation des Projektes "OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien". (Projektteil Fasern) T2 - Fachgespräch zur OECD - TG PSD - BMU BMWi BAM BAuA UBA CY - Online meeting DA - 10.09.2021 KW - Nano KW - Nanofasern KW - OECD KW - Prüfrichtlinie KW - Nanomaterial PY - 2021 AN - OPUS4-53826 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Florian, Camilo T1 - Influence of oxidation in the formation and performance of laser-induced periodic surface structures N2 - The fabrication of laser-induced periodic surface structures (LIPSS) has been reported for metallic, semiconductor and dielectric materials when irradiated with linearly polarized ultrashort laser pulses. Different sets of processing parameters have been identified and extensively studied, allowing the use of LIPSS for applications in medicine, tribology and surface wetting to name a few. One important parameter that is often not considered is the laser-induced oxidation that is produced especially when oxidation prone materials are irradiated in air environment. This surface oxidation can potentially influence the final structures size, shape and orientation and modify their functionality in some specific applications. In this work, we first study the influence of the laser-induced oxidation layer on the formation of LIPSS by characterizing the response of the oxidation prone hard-coating material chromium nitride. Moreover, we employ complementary surface and depth-profiling analytic techniques to reveal morphological, chemical and structural features of different types of surface structures and LIPSS produced on titanium-based substrates. Finite-difference time-domain (FDTD) calculations finally explain how this superficial oxidation layer promotes the formation of a new type of low spatial frequency LIPSS. Also, we measure the depth-extent of the different oxides formed and demonstrate its beneficial influence for friction reduction and wear resistance applications. T2 - SPIE Photonics West Conference, Symposium "Laser-Based Micro- and Nano-Processing XVI" CY - San Francisco, CA, USA DA - 22.01.2022 KW - Laser-induced periodic surface structures (LIPSS) KW - Oxidation KW - Femtosecond laser KW - Laser processing KW - Finite-difference time-domain calculations (FDTD) PY - 2022 AN - OPUS4-54322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Esmann, M. A1 - Chimeh, A. A1 - Korte, A. A1 - Zhong, J. A1 - Stephan, S. A1 - Witt, Julia A1 - Wittstock, G. A1 - Talebi, N. A1 - Lienau, C. T1 - Plasmonic nanofocusing spectral interferometry N2 - We describe and demonstrate a novel experimental approach to measure broadband, amplitude- and phase-resolved scattering spectra of single nanoparticles with 10-nm spatial resolution. Nanofocusing of Surface plasmon polaritons (SPPs) propagating along the shaft of a conical gold taper is used to create a spatially isolated, spectrally broad nanoscale light source at ist very apex. The interference between these incident SPPs and SPPs that are backpropagating from the apex leads to the formation of an inherently phase-stable interferogram, which we detect in the far field by partially scattering SPPs off a small protrusion on the taper shaft. We show that these interferograms allow the reconstruction of both the amplitude and phase of the local optical near fields around individual nanoparticles optically coupled to the taper apex. We extract local light scattering spectra of particles and quantify line broadenings and spectral shifts induced by tip-sample coupling. Our experimental findings are supported by corresponding finite-difference time-domain and coupled dipole simulations and Show that, in the limit of weak tip-sample coupling, the measurements directly probe the projected local density of optical states of the plasmonic system. The combination of a highly stable inline interferometer with the inherent optical background suppression through nanofocusing makes it a promising tool for the locally resolved study of the spectral and temporal optical response of coupled hybrid nanosystems. KW - Plasmonic nanofocusing KW - Near-field spectroscopy PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-504985 DO - https://doi.org/10.1515/nanoph-2019-0397 VL - 9 IS - 2 SP - 491 EP - 508 PB - De Gruyter AN - OPUS4-50498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knigge, Xenia T1 - First Experiences with the new HAXPES@BAM N2 - This talk was part of the inauguration event for the new x-ray photoelectron spectrometer with the possibility to measure HAXPES (hard energy x-ray photoelectron spectroscopy). With HAXPES detailed chemical information can now be gained not only from the first outermost nanometres of the sample surface, but also from deeper regions. In this talk first results and experiences handling the spectrometer are shown. T2 - Inauguration of the HAXPES@BAM - A new Hard-X-Ray Photoelectron Spectrometer CY - Online meeting DA - 25.01.2022 KW - HAXPES KW - Nano@BAM KW - Surface Analysis KW - XPS PY - 2022 UR - https://www.bam.de/Content/EN/Events/2022/2022-01-25-hapex.html AN - OPUS4-54434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Sebastian A1 - Cappella, Brunero T1 - Study of micro- and nanoscale wetting properties of lubricants using AFM force-distance curves N2 - Atomic force microscopy (AFM) plays an important role as a multifuntional tool in nanotribology.In the present work it was shown that the main features of force-distance curves on different lubricants have been characterized and the underlying phenomena could be explained. KW - Lubricants KW - Atomic force microscopy KW - Force-distance curves PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-504631 DO - https://doi.org/10.1007/s11249-020-1275-3 SN - 1573-2711 VL - 68 IS - 1 SP - 1 EP - 12 PB - Springer CY - Cham AN - OPUS4-50463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Fritzsche, Sven A1 - Weimann, Christiane A1 - Pauw, Brian Richard A1 - Sturm, Heinz T1 - 2PP-TestArtifact N2 - This repository contains a test artifact (TA), also called test structure, designed for two-photon polymerization (also known as Direct Laser Writing (DLW) or Two/Multi-photon lithography (2PA/MPA)). Test artifacts can be used to compare structures, to check options used by the slicer, check the state of the 2PP machine itself or to get a construction guidelines for a certain combination of power, velocity and settings. The associated paper can be found here: https://dx.doi.org/10.1088/1361-6501/acc47a General ideas behind the test artifact: 1. optimized for 2PP-DLW 2. should be fast and easy to analyse with optical microscopy or 3. scanning electron microscopy without tilt. 3. short time to fabricate 4. include a reasonable amount of different features 5. bulk and small structures on the substrate KW - Reference structure KW - Calibration structure KW - Test structure KW - Laser writing KW - Two-photon polymerization KW - 3D printing KW - Additive manufacturing KW - Microprinting KW - Multi-photon light structuring PY - 2023 DO - https://doi.org/10.6084/m9.figshare.22285204.v2 PB - Digital Science CY - Cambridge, MA, USA AN - OPUS4-57165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Spaltmann, Dirk T1 - Editorial: Special issue "Laser-induced periodic surface nano- and microstructures for tribological applications" N2 - Laser material processing is an emerging technology that generates surface functionalities on the basis of optical, mechanical, or chemical properties. In the form of laser surface texturing (LST), it has attracted a remarkable amount of research to tailor surface properties towards various tribological applications. The main advantages of this single-step, laser-based technology are the contactless machining, featuring a high flexibility, efficiency, and speed, along with the excellent quality of the processed products. LST can be applied precisely localized to sub-micrometric areas, but, via laser beam scanning, it is also feasible for structuring large surface areas at the square meter size. This Special Issue focuses on the latest developments concerning the tribological performance of laser-generated periodic surface nano- and microstructures and their applications. This includes the laser-based processing of different surface patterns, such as “self-organized” laser-induced periodic surface structures (LIPSS, ripples), grooves, micro-spikes, hierarchical hybrid nano-/micro-structures, microfeatures generated by direct laser interference patterning (DLIP), or even dimples or other topographic geometries shaped by direct laser modification or ablation. The applications of these periodically nano- and micro-patterned surfaces may improve the lubricated or non-lubricated tribological performance of surfaces in conformal and even non-conformal contact through a reduction of wear, a variation of the coefficient of friction, altered load carrying capacity, etc., resulting in energy saving, improved reliability, increased lifetimes as well as durability, leading in turn to extended maintenance intervals/reduced down-time. This can be beneficial in terms of bearings, gears, engines, seals, cutting tools, or other tribological components. Fundamental aspects addressed may involve the investigation of the relevant physical and chemical effects accompanying the laser-generated nano- and microscale topographies, such as alterations of the material structures, the hardness, superficial oxidation, the role of additives contained in lubricants, surface wettability, micro-hydrodynamic effects, etc. For this Special Issue we aim to attract both academic and industrial researchers and would like to provide a bridge between research in the fields of tribology and laser material processing in order to foster the current knowledge and present new ideas for future applications and new technologies. KW - Laser-induced periodic surface structures (LIPSS) KW - Tribology KW - Applications KW - Wear KW - Friction PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505948 DO - https://doi.org/10.3390/lubricants8030034 SN - 2075-4442 VL - 8 IS - 3 SP - 34, 1 EP - 34, 3 PB - MDPI CY - Basel AN - OPUS4-50594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Battig, Alexander A1 - Abdou-Rahaman Fadul, Naïssa A1 - Frasca, Daniele A1 - Schulze, Dietmar A1 - Schartel, Bernhard T1 - Multifunctional graphene nanofiller in flame retarded polybutadiene/chloroprene/carbon black composites N2 - To curtail flammability risks and improve material properties, flame retardants (FRs) and fillers are mixed into rubbers. High loadings of aluminum trihydroxide (ATH) and carbon black (CB) are the most used FRs and reinforcing additive, respectively, in rubbers. To reduce loading without losing mechanical properties, partial substitution of ATH as well as CB by low amounts of multilayer graphene (MLG) nanoparticles is investigated. The high aspect ratio MLG is made of ten graphene sheets. In polybutadiene/chloroprene (BR/CR) nanocomposites 3 phr MLG replaced 15 phr CB and/or 3 phr ATH. Material and mechanical properties as well as fire behavior of the nanocomposites are compared to BR/CR with 20 phr CB both with and without 50 phr ATH. MLG appears as a promising nanofiller to improve the functional properties: replacement of CB improved rheological, curing, and mechanical properties; substitution of ATH improved nanocomposite properties without affecting flame retardancy. KW - Nanocomposites KW - Rubber KW - Multilayer graphene KW - Carbon black KW - Polybutadiene/chloroprene KW - Graphene PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523468 DO - https://doi.org/10.1515/epoly-2021-0026 SN - 1618-7229 VL - 21 IS - 1 SP - 244 EP - 262 PB - De Gruyter AN - OPUS4-52346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dub, S. A1 - Haftaoglu, Cetin A1 - Kindrachuk, Vitaliy T1 - Estimate of theoretical shear strength of C60 single crystal by nanoindentation N2 - The onset of plasticity in a single crystal C60 fullerite was investigated by nanoindentation on the (111) crystallographic plane. The transition from elastic to plastic deformation in a contact was observed as pop-in events on loading curves. The respective resolved shear stresses were computed for the octahedral slip systems ⟨011¯¯¯⟩{111}, supposing that their activation resulted in the onset of plasticity. A finite element analysis was applied, which reproduced the elastic loading until the first pop-in, using a realistic geometry of the Berkovich indenter blunt tip. The obtained estimate of the C60 theoretical shear strength was about 1/11 of the shear modulus on {111} planes. KW - Finite element analysis KW - Fullerite KW - Nanoindentation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523208 DO - https://doi.org/10.1007/s10853-021-05991-2 VL - 56 IS - 18 SP - 10905 EP - 10914 PB - Springer Nature AN - OPUS4-52320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolmangadi, Mohamed Aejaz T1 - Side Chain length dependent dynamics and conductivity of self assembled ion channels N2 - We study the molecular mobility and electrical conductivity of a homologous series of linear shaped columnar ionic liquid crystals ILCn, (n = 8, 10, 12, 14, 16) using Broadband Dielectric Spectroscopy (BDS), Specific Heat Spectroscopy (SHS), and X-ray scattering. We aim to understand how the alkyl chain length influences the dynamics and electric conductivity in this system. Two dielectrically active relaxation modes are observed, the and the αcore process, that correspond to the localized relaxation of the alkyl chains, and cooperative motions of the aromatic core in the columns respectively. Both the relaxation and the αcore process slow down with increasing alkyl chain length. SHS reveals one relaxation process, the αalkyl process that has similar temperature dependence as that of the αcore process for ILC12, 14, 16 but shifts to higher temperature for ILC8 and 10. For ILC12, 14, 16 the absolute values of DC conductivity increase by 4 orders of magnitude at the transition from the plastic crystalline to hexagonal columnar phase. For ILC8, 10 the DC conductivity behavior is similar to ionic liquids, where the conductivity is coupled with structural relaxation. Small-Angle X-ray (SAXS) investigations reveal that both the intercolumnar distance and disorder coherence length increase with alkyl chain length, conversely the DC conductivity decreases monotonically. T2 - 11th IDS conference 2022 CY - San Sebastian, Spain DA - 03.09.2022 KW - Glass transition KW - Conductivity KW - Fast Scanning Calorimetry KW - Dynamics PY - 2022 AN - OPUS4-55878 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolmangadi, Mohamed Aejaz T1 - Suppressed Transition and Dynamic self-asembly of ionic superdiscs in cylindrical nanochannels N2 - Liquid crystalline mesophases in nanoconfinement exhibit intriguing phase transition behaviors and relaxation dynamics. Here, we investigate the molecular mobility and electrical conductivity of a columnar ionic liquid crystal confined in self-ordered nanoporous alumina oxide membranes of pore size ranging from 180 nm down to 25 nm. We use nano-broadband dielectric spectroscopy (BDS) and calorimetry to study the dynamics and phase behavior. Calorimetric investigation reveals a complete suppression of the columnar – isotropic transition, while the plastic crystalline – columnar transition temperature decreases with inverse pore size and deviates from the Gibbs – Thomson equation. For the bulk case, BDS detects two relaxation modes in the crystalline phase, the γ relaxation and the α1 relaxation, and two relaxation modes in the columnar phase, the α2 and α3 relaxation. All relaxation modes slow down for the confined case compared to the bulk. However, a new relaxation mode reflecting the interfacial layer emerges for the 80 and 25 nm. We discuss the possible molecular origins of the different relaxation modes observed. For the bulk ILC, a clear jump of 4 orders of magnitude in the absolute values of DC conductivity occurs at the transition from the plastic crystalline to hexagonal columnar phase, for the confined ILC, this transition is smooth. DC conductivity is reduced for the confined case, except for the 25nm, where the values are similar to the bulk. T2 - DPG Spring Meet 2023 CY - Dresden, Germany DA - 26.03.2023 KW - Ionic Liquid crystals KW - Nanoconfinement KW - Conductivity PY - 2023 AN - OPUS4-57345 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement by Monte-Carlo based particle scattering Simulations N2 - Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined.[1] Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. To estimate these effects, particle scattering simulations are applied. In general, different approaches for modeling the AuNP and their distribution within the cell are possible. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. [2] These models are applicable to simulations of internal emitters and external radiation sources. Most of the current studies on AuNP focus on external beam therapy. In contrast, we apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. These results are the foundation for ongoing experimental work which aims to obtain a mechanistic understanding of cell death induced by radioactive 198Au. T2 - #RSCposter 2023 CY - Online meeting DA - 28.02.2023 KW - AuNP KW - Beta decay KW - Brachytherapy KW - Cancer treatment KW - Clustered nanoparticles KW - DNA KW - DNA damage KW - Dosimetry KW - Energy deposit KW - Geant4 KW - Geant4-DNA KW - Gold Nanoparticles KW - LEE KW - Livermore model KW - Low energy electrons KW - MCS KW - Microdosimetry KW - Monte-Carlo simulation KW - NP KW - OH radical KW - Penelope model KW - Radiation damage KW - Radiation therapy KW - Radiationtherapy KW - Radiotherapy KW - Radioactive decay KW - Radiolysis KW - Simulation KW - TOPAS KW - TOPAS-nbio KW - beta particle KW - particle scattering PY - 2023 AN - OPUS4-57060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hildebrand, G. A1 - Sänger, Johanna Christiane A1 - Schirmer, U. A1 - Mantei, W. A1 - Dupuis, Y. A1 - Houbertz, R. A1 - Liefeith, K. T1 - Process Development for Additive Manufacturing of Alumina Toughened Zirconia for 3D Structures by Means of Two-Photon Absorption Technique N2 - Additive manufacturing is well established for plastics and metals, and it gets more and more implemented in a variety of industrial processes. Beside these well-established material platforms, additive manufacturing processes are highly interesting for ceramics, especially regarding resource conservation and for the production of complex three-dimensional shapes and structures with specific feature sizes in the µm and mm range with high accuracy. The usage of ceramics in 3D printing is, however, just at the beginning of a technical implementation in a continuously and fast rising field of research and development. The flexible fabrication of highly complex and precise 3D structures by means of light-induced photopolymerization that are difficult to realize using traditional ceramic fabrication methods such as casting and machining is of high importance. Generally, slurry-based ceramic 3D printing technologies involve liquid or semi-liquid polymeric systems dispersed with ceramic particles as feedstock (inks or pastes), depending on the solid loading and viscosity of the system. This paper includes all types of photo-curable polymer-ceramic-mixtures (feedstock), while demonstrating our own work on 3D printed alumina toughened zirconia based ceramic slurries with light induced polymerization on the basis of two-photon absorption (TPA) for the first time. As a proven exemplary on cuboids with varying edge length and double pyramids in the µm-range we state that real 3D micro-stereolithographic fabrication of ceramic products will be generally possible in the near future by means of TPA. This technology enables the fabrication of 3D structures with high accuracy in comparison to ceramic technologies that apply single-photon excitation. In sum, our work is intended to contribute to the fundamental development of this technology for the representation of oxide-ceramic components (proof-of-principle) and helps to exploit the high potential of additive processes in the field of bio-ceramics in the medium to long-term future. KW - Additive manufacturing KW - Ceramics 3D printing KW - Two-photon adsorption KW - Polymer-ceramic mixtures KW - Bio-ceramic engineering PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526672 DO - https://doi.org/10.3390/ceramics4020017 VL - 4 IS - 2 SP - 224 EP - 239 PB - MDPI CY - Basel AN - OPUS4-52667 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waniek, Tassilo A1 - Braun, U. A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - The impact of water released from boehmite nanoparticles during curing in epoxy-based nanocomposites N2 - The enhancing effect on mechanical properties of boehmite (γ-AlOOH) nanoparticles (BNP) in epoxy-based nanocomposites on the macroscopic scale encouraged recent research to investigate the micro- and nanoscopic properties. Several studies presented different aspects relatable to an alteration of the epoxy polymer network formation by the BNP with need for further experiments to identify the mode of action. With FTIR-spectroscopic methods this study identifies interactions of the BNP with the epoxy polymer matrix during the curing process as well as in the cured nanocomposite. The data reveals that not the BNP themselves, but the water released from them strongly influences the curing process by hydrolysis of the anhydride hardener or protonation of the amine accelerator. The changes of the curing processes are discussed in detail. The changes of the curing processes enable new explanation for the changed material properties by BNP discussed in recent research like a lowered glass transition temperature region (Tg) and an interphase formation. KW - Spectroscopy KW - Aluminium oxide hydroxide KW - Glass transition temperature KW - Material chemistry KW - Nanocomposites KW - Structure-property relationship PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527202 DO - https://doi.org/10.1002/app.51006 VL - 138 IS - 39 SP - 51006 PB - Wiley Periodicals LLC CY - Hoboken AN - OPUS4-52720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra T1 - Bestimmung der Partikelgrößen-verteilung mittels Zentrifugen-Sedimentationsverfahren nach ISO 13318-2 (Küvette) N2 - Im Vortrag werden das Messprinzip einer Photozentrifuge erläutert und die Anforderungen der zugrundeliegenden Normen diskutiert. Die praktische Durchführung der Messung und insbesondere auch die vorbereitenden Arbeiten, sowie die Auswertung der Rohdaten bilden den Schwerpunkt des Vortrags. Gezeigt werden auch die Validierung sowie ein Beispiel zur regelmäßigen Verifizierung des Verfahrens. Nach Anwendungsbeispielen und Vergleichen zu Ergebnissen mit anderen Messverfahren, wird das Verfahren in einer Zusammenfassung bewertet. T2 - Seminar Rheologie und Stabilität von dispersen Systemen CY - Potsdam, Germany DA - 08.05.2023 KW - CLS KW - Particle size KW - Nano PY - 2023 AN - OPUS4-57679 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard T1 - Small but Great – Multifunctional Graphene in Rubber Nanocomposites N2 - A few layer/multilayer graphene (MLG) with a specific surface area of BET ≥ 250 m2/g is proposed as an efficient multifunctional nanofiller for rubbers. The preparation method, i.e., ultrasonically-assisted solution or latex premixing of master batches followed by conventional two-roll milling, strongly influences the dispersion in the elastomeric matrix and is fundamental for the final properties. When homogenously dispersed, single stacks of only approximately 10 graphene sheets, with an aspect ratio of ca. 35, work at low loadings, enabling the replacement of large amounts of carbon black (CB), an increase in efficiency, and a reduction in filler load. The appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing, gas barrier properties, electrical and thermal conductivity, as well as mechanical properties of different rubbers, as shown for chlorine-Isobutylene-Isoprene rubber (CIIR), nitrile-butadiene rubber (NBR), natural rubber (NR), and styrene-butadiene rubber (SBR).[1-5] 3 phr of MLG tripled the Young’s modulus of CIIR, an effect equivalent to 20 phr of CB. The stronger interactions between MLG and NR or SBR also resulted in a reduction in the elongation at break by 20% and 50%, respectively, while the same parameter was hardly changed for CIIR/MLG and NBR/MLG. CIIR/MLG and NBR/MLG were stiffer but just as defomable than CIIR and NBR. The strong reinforcing effect of 3 phr MLG was confirmed by the increase of greater than 10 Shore A in hardness. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards flammability. We investigated MLG also as a synergist for reducing the aluminium trihydrate loading in flame retardant hydrogenated acrylonitrile-butadiene (HNBR), polybutadiene chloroprene (BR/CR), and chlorosulfonated polyethylene rubber(CSM).[6-8] The higher the nanofiller concentration is, the greater the improvement in the properties. For instance, the permeability decreased by 30% at 3 phr of MLG, 50% at 5 phr and 60% at 10 phr, respectively. Moreover, the MLG nanocomposites improve stability of mechanical properties against the effects of weathering. In key experiments an increase in UV-absorption and a pronounced radical scavenging were proved as stabilizing mechanisms. In a nutshell, MLG is an efficient multifunctional nanofiller ready to be used for innovative rubber development. T2 - 34th PDDG Conference CY - Dubrovnik, Croatia DA - 11.06.2023 KW - Graphene KW - Nanocomposites KW - Reinforcement KW - Antioxydant KW - Flame retardant KW - Durability PY - 2023 AN - OPUS4-57693 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Omar, Hassan T1 - Growth Kinetics and Molecular Mobility of the Adsorbed Layer of Poly(bisphenol-A Carbonate) (PBAC), Polysulfone (PSU), and Poly (2-Vinyl Pyridine) (P2VP) N2 - Interactions between a polymer and a substrate interface play a vital role in understanding the improvement in thin film material properties as well as serving as a model for nanocomposites. For any non-repulsive polymer-substrate interactions, polymer segments form an irreversibly adsorbed layer and show a slowdown in the glassy dynamics and thus an increase in the thermal glass transition temperature compared to the bulk-like values. The growth kinetics of the adsorbed layer obey a two-step mechanism: formation of immobilized layer with flat segmental conformations and a loosely bound layer with stretched chains pinned to the surface. Here the adsorbed layer was studied for: poly (bisphenol-A carbonate) (PBAC) and polysulfone (PSU), two bulky polymers containing a functional group (phenyl ring) in the backbone and compared to poly (2-vinyl pyridine) (P2VP), where the backbone is a vinyl-derivative and the functional group (pyridine) is in the side chain. The growth kinetics for PBAC and PSU were found to deviate from the well-known mechanism, observed for polymers such as P2VP. Atomic force microscopy and ellipsometry were used for this investigation and was additionally supported by broadband dielectric spectroscopy. T2 - 11th International Conference on Times of Polymers (TOP) and Composites CY - Ischia, Italy DA - 11.06.2023 KW - Adsorbed Layer KW - Dielectric Spectroscopy KW - Atomic Force Microscopy KW - Ellipsometry KW - Growth Kinetics KW - Molecular Mobility PY - 2023 AN - OPUS4-57709 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas T1 - New analytic ways to characterise mesoporous thin layers used in electrocatalytic water splitting N2 - Mesoporous materials are needed in many applications where a high specific surface area and adsorptive behaviour is needed. Important examples are separation techniques and barrier layers and catalysts. Electrochemical water splitting is the key technology for producing green hydrogen and there is no foreseeable alternative to this process for producing elementary hydrogen from green electrical power. Water electrolysis can be divided into the anodic Oxygen Evolution Reaction (OER) and the cathodic Hydrogen Evolution Reaction (HER). Both processes have to be heavily optimised to a large extent to avoid energy losses caused by overvoltage. The development of electrodes for these processes is especially difficult due to the many boundary conditions. Water splitting is a catalytic as well as electrochemical process. The contact area between the electrolyte and the electrode must be maximised maintaining the stability of the surface. Side reactions must be suppressed, and effective gas transport must be ensured. The whole process has to be tolerant with respect to temperature, harsh chemical conditions from the electrolyte as well as high current densities. We present a hybrid analytical method combining several analytical techniques for determining the properties of thin layers of mixed oxides of the general composition Ir:TiOx. These materials are promising candidates for electrocatalytical top coatings of OER electrodes. To lower the costs of the electrolysers, the main goal is to lower the Ir content retaining the system efficiency. The main properties which are hard to determine are the porous volume fraction and the Ir:Ti element ratio. By a combination of electron microscopy, spectroscopic operando ellipsometry, ellipsometric porosimetry, and other techniques, we can determine key features of mesoporous thin layer materials. We aim to develop operando capable techniques used in process monitoring as well as measurement techniques optimised for accuracy. By developing reference materials, we support long term uptake of our methodology. This work can directly be used for optimising electrocatalytic layers and is a good example for the power of hybrid metrology for improving materials design. T2 - International Conference on Resource Chemistry CY - Alzenau, Germany DA - 11.03.2024 KW - Ellipsometry KW - Electrocatalytic Water Splitting KW - Mesoporous Materials KW - Electron Probe Microanalysis KW - Hydrogen Generation PY - 2024 AN - OPUS4-59764 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina T1 - Spatial Inhomogeneity, Interfaces and Complex Vitrification Behavior of Epoxy-based Materials N2 - This work deals with an in-depth comparative investigation of the structure, molecular mobility and vitrification kinetics of three bisphenol A diglycidyl ether (DGEBA)-based materials with different nanofillers: taurine-modified layered double hydroxide (T-LDH) and halloysite nanotubes (HNTs). The chosen methodology comprises I) small – and wide – angle X-ray scattering (SAXS/WAXS) II) calorimetry in the forms of a) conventional DSC and b) static fast scanning calorimetry (FSC), III) broadband dielectric spectroscopy (BDS), as well as IV) specific heat spectroscopy in the forms of a) temperature modulated DSC, and b) temperature modulated FSC. T2 - Abteilungsseminar 6. - FB 6.6 CY - Online meeting DA - 06.05.2021 KW - Broadband dielectric spectroscopy KW - Epoxy nanocomposites KW - Halloysite nanotubes KW - X-ray scattering KW - Differential scanning calorimetry KW - Rigid amorphous fraction KW - Flash DSC PY - 2021 AN - OPUS4-52697 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Surface oxidation accompanying the formation of various types of femtosecond laser-generated surface structures on titanium alloy N2 - Different types of laser-generated surface structures, i.e., Laser-induced Periodic Surface Structures (LIPSS, ripples), Grooves, and Spikes are generated on titanium and Ti6Al4V surfaces by means of femtosecond (fs) laser scan processing (790 nm, 30 fs, 1 kHz) in ambient air. Morphological, chemical and structural properties of the different surface structures are characterized by various surface analytical techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Glow discharge optical emission spectroscopy (GD-OES), and depth-profiling Auger electron spectroscopy (AES). It is revealed that the formation of near-wavelength sized LIPSS is accompanied by the formation of a graded oxide extending several tens to a few hundreds of nanometers into depth. GD-OES performed on other superficial fs-laser generated structures produced at higher fluences and effective number of pulses per spot area such as periodic Grooves and irregular Spikes indicate even thicker graded oxide layers. These graded layers may be suitable for applications in prosthetics or tribology. T2 - E-MRS Spring Meeting 2021 CY - Online meeting DA - 31.05.2021 KW - Laser-induced periodic surface structures (LIPSS) KW - Titanium alloy KW - Oxidation KW - Glow-discharge optical emission spectroscopy PY - 2021 AN - OPUS4-52749 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - The role of electromagnetic scattering in the formation of laser-induced periodic surface structures N2 - Laser-induced periodic surface structures (LIPSS) are a universal phenomenon that is accompanying laser materials processing. These surface nanostructures pave a simple way for surface functionalization with numerous applications in optics, fluidics, tribology, medicine, etc. During the last decade remarkable experimental and theoretical improvements in understanding of their formation mechanisms were obtained - all pointing toward polarization-dependent energy deposition by absorption of optical radiation that is scattered at the surface roughness and interfering with the laser beam. This contribution reviews the current state-of-the-art on the role of electromagnetic scattering in the formation of LIPSS by ultrashort laser pulses. Special attention is drawn to recent finite-difference time-domain (FDTD) calculations that allow to visualize the radiation patterns formed in the vicinity of the sample surface and to the impact of a thin superficial laser-induced oxidation layer. T2 - E-MRS Spring Meeting 2021 CY - Online meeting DA - 31.05.2021 KW - Laser-induced periodic surface structures (LIPSS) KW - Optical scattering KW - Oxidation KW - Femtosecond laser PY - 2021 AN - OPUS4-52729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Angurel, L.A. T1 - Effects of laser surface processing under different atmospheres on the superconducting properties of pure niobium N2 - Niobium metal is the pure element with the highest superconducting critical temperature (T_c = 9.2 K), which is present in many applications. Particularly, in superconducting radio frequency (SRF) cavities of particle accelerators, the control of the surface characteristics of pure Nb is crucial, as the presence of defects may generate magnetic flux pinning that can increase by more than two orders of magnitude the surface critical current, ic. Several procedures such as chemical- or electro-polishing have been used aiming at cleaning surface contamination and decreasing its roughness. Sub-nanosecond lasers can be applied to generate a broad range of micro and nanostructures (e.g. Laser-Induced Periodic Surface Structures, LIPSS) that strongly modify the materials properties - as wettability, color, oxidation resistance or antibacterial behavior. In this work, we analyze a variety of surface structures generated on pure Nb sheets with different laser systems (UV, Vis and n-IR, fs and ps) by exploring a range of processing parameters. These include pulse overlap, irradiance or the effective number of pulses, under different atmospheres (air, N2, Ar, vacuum). The effects on Tc, critical currents and critical fields (Bc1, Bc2 and Bc3) have been obtained from magnetization, ac susceptibility and heat capacity measurements, revealing their dependence with the different surface nanostructures and the chemical changes generated with these laser treatments. T2 - E-MRS Spring Meeting 2021 CY - Online meeting DA - 31.05.2021 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Niobium KW - Superconductivity PY - 2021 AN - OPUS4-52730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Data processing and nonlinear curve Fitting with fityk N2 - A brief introduction into fityk is given. The introduction is followed by a pratical session. Fityk is a versatile data processing tool for nonlinear curve fitting. T2 - AFM Data analysis seminar CY - Online meeting DA - 23.02.2021 KW - Fityk KW - Curve fitting KW - Analysis KW - Raman KW - IR KW - XPS PY - 2021 AN - OPUS4-52154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fiedler, Saskia T1 - Cathodoluminescence of Silicon Nanoparticles N2 - In this work, Mie resonances in single Si nanoparticles (NPs) of different sizes have been systematically studied, using dark field (DF) and cathodoluminescence (CL) spectroscopy. An analytical method has been developed to compare experiment with theory. Experimental CL spectra are averaged over entire Si NPs, allowing for direct comparison to DF spectra of identical NPs. Theoretical spectra clarify the assignment of Mie resonances within the NP which contribute with different intensity in DF and CL, resulting in an apparent spectral shift. Furthermore, a substrate effect appears. A 100 nm-Si NP on 15 nm SiN results in a broad peak, spectrally in between that of the calculated electric and magnetic dipole, a NP on 50 nm SiN exhibits two separated peaks as theoretically predicted. High spatial resolution of electron beam excitation allows to study the spectral CL changes at varying beam impact parameters. Theory and experiment agree that depending on beam position within a small Si NP, relative intensity of electric and magnetic dipole change; electric dipole vanishing in the center of the NP. Similar results are found for larger (d = 210 nm) Si NPs although the mode assignment is challenging as higher order modes appear and overlap with others. In conclusion, comparison of CL and DF spectra is not trivial, in fact, excitation/radiation of distinct Mie resonances within a single Si NP are dependent on beam placement. However, substrate effects need to be considered in CL. T2 - European Material Research Society Fall Meeting 2021 CY - Online meeting DA - 20.09.21 KW - Cathodoluminescence KW - Silicon nanoparticles KW - Mie resonances PY - 2021 AN - OPUS4-53439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN ED - Bonse, Jörn ED - Spaltmann, Dirk T1 - Laser-induced periodic surface nano- and microstructures for tribological applications N2 - This book is a reprint collection of articles from the Special Issue published online in the open access journal Lubricants. KW - Laser-induced periodic surface structures (LIPSS) KW - Friction KW - Wear KW - Applications PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516611 UR - https://www.mdpi.com/books/pdfview/book/3130 SN - 978-3-03943-523-4 SN - 978-3-03943-524-1 SP - 1 EP - 180 PB - MDPI CY - Basel AN - OPUS4-51661 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Santos, C.I.L. A1 - Machado, W.S. A1 - Wegner, Karl David A1 - Gontijo, L.A.P. A1 - Bettini, J. A1 - Schiavon, M.A. A1 - Reiss, P. A1 - Aldakov, D. T1 - Hydrothermal Synthesis of Aqueous-Soluble Copper Indium Sulfide Nanocrystals and Their Use in Quantum Dot Sensitized Solar Cells N2 - facile hydrothermal method to synthesize water-soluble copper indium sulfide (CIS) nanocrystals (NCs) at 150 degrees C is presented. The obtained samples exhibited three distinct photoluminescence peaks in the red, green and blue spectral regions, corresponding to three size fractions, which could be separated by means of size-selective precipitation. While the red and green emitting fractions consist of 4.5 and 2.5 nm CIS NCs, the blue fraction was identified as in situ formed carbon nanodots showing excitation wavelength dependent emission. When used as light absorbers in quantum dot sensitized solar cells, the individual green and red fractions yielded power conversion efficiencies of 2.9% and 2.6%, respectively. With the unfractionated samples, the efficiency values approaching 5% were obtained. This improvement was mainly due to a significantly enhanced photocurrent arising from complementary panchromatic absorption. KW - Aqueous quantum dot KW - Solar cells KW - CUINS2 nanocrystals KW - Colloidal semiconductor nanocrystals PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517983 DO - https://doi.org/10.3390/nano10071252 VL - 10 IS - 7 SP - 1252 PB - MDPI AN - OPUS4-51798 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cubero, A. A1 - Martínez, E. A1 - Angurel, L.A. A1 - de la Fuente, G.F. A1 - Navarro, R. A1 - Legall, Herbert A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Surface superconductivity changes of niobium sheets by femtosecond laser-induced periodic nanostructures N2 - Irradiation with ultra-short (femtosecond) laser beams enables the generation of sub-wavelength laser-induced periodic surface structures (LIPSS) over large areas with controlled spatial periodicity, orientation, and depths affecting only a material layer on the sub-micrometer scale. This study reports on how fs-laser irradiation of commercially available Nb foil samples affects their superconducting behavior. DC magnetization and AC susceptibility measurements at cryogenic temperatures and with magnetic fields of different amplitude and orientation are thus analyzed and reported. This study pays special attention to the surface superconducting layer that persists above the upper critical magnetic field strength Hc2, and disappears at a higher nucleation field strength Hc3. Characteristic changes were distinguished between the surface properties of the laser-irradiated samples, as compared to the corresponding reference samples (non-irradiated). Clear correlations have been observed between the surface nanostructures and the nucleation field Hc3, which depends on the relative orientation of the magnetic field and the surface patterns developed by the laser irradiation. KW - Niobium KW - Surface superconductivity KW - Laser-induced periodic surface structures (LIPSS) KW - Nanostructures PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-518462 DO - https://doi.org/10.3390/nano10122525 SN - 2079-4991 VL - 10(12) IS - Special issue "Laser-generated periodic nanostructures" SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-51846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Formation of laser-induced periodic surface structures observed with extreme temporal and spatial resolution N2 - Laser-induced periodic surface structures (LIPSS) have gained remarkable attention as they represent a universal phenomenon that is often accompanying laser-processing. Such LIPSS enable a plethora of different surface functionalizations for applications in the fields of optics, fluidics, tribology, or medicine. Due to the inherent multiscale nature of processes involved in LIPSS formation, their in-situ observation requires experimental techniques that combine high temporal resolution with the appropriate spatial resolution. In this respect fourth generation light sources, namely short wavelength, short pulse free electron lasers (FELs) are offering new and fascinating possibilities. This work contribution will discuss the results of scattering experiments carried at the FLASH free electron laser at DESY (Hamburg, Germany), which allowed us to resolve laser-induced structure formation at surfaces on the nm to sub-µm length scale and in temporal regimes ranging from ps to several ns with sub-ps resolution. A ps-optical pump / fs-XUV scattering probe scheme was employed to 100 nm thick laser-excited silicon films, while recording snapshots of the transmitted XUV scattering patterns at various delay times after the laser pulse impact. On timescales ranging from hundred ps until several ns almost quantitative agreement was observed between certain features of the recorded scattering patterns and predictions of the first-principles theory of J.E. Sipe and coworkers. Other scattering features appearing with a delay of ~100 ps and lasting for ~1 ns are attributed to capillary surface waves being excited at the laser-melted film material while ablation proceeds. Our superior spatio-temporal resolution experiments allow to uniquely reveal and distinguish early signatures of coherent/plasmonic electromagnetic scattering effects, separately followed by hydrodynamic matter reorganization. T2 - EMRS Spring Meeting 2023, 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 - XUV scattering KW - Free electron laser KW - Pump-probe KW - Capillary waves PY - 2023 AN - OPUS4-57601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Single Femtosecond Laser Pulse induced Amorphization, Re-crystallization and Native Oxide Removal at Silicon Wafer Surfaces N2 - Single femtosecond laser pulse induced amorphization, re-crystallization and native oxide layer removal at silicon wafer surfaces of different crystal orientation is studied via spectroscopic imaging ellipsometry, atomic force microscopy, and high-resolution transmission electron microscopy. T2 - 2023 Conference on Lasers and Electro-Optics/Europe – European Quantum Electronics Conferences CY - Munich, Germany DA - 26.06.2023 KW - Femtosecond laser KW - Laser-induced amorphization KW - Spectroscopic imaging ellipsometry KW - Transmission electron microscopy KW - Native oxide layer PY - 2023 AN - OPUS4-57829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoell, A. T1 - On the usage of anomalous SAXS to analyzethe structure and composition of bimetallic nanoparticles and quantum dots N2 - Tailor-made nanoparticles are of increasing interest in e.g. catalysis, as sensor materials, analytical assays, or can have superior photophysical properties. A major issue concerning the preparation of high-quality and functional nanoparticles is a good control of particle size, shape, polydispersity, and composition. Small Angle X-ray Scattering (SAXS) is a non-destructive method for the analysis of nanostructures in a wide variety of materials. This method allows determining averaged structural parameters on a length scale from just above atomic sizes up to several 100 nanometers such as sizes, size distributions, volume fractions, and inner surface sizes. Moreover, anomalous Small Angle X-ray Scattering (ASAXS) exploits the anomalous dispersion of the scattering amplitudes near the X-ray absorption edges of the elements contained in the sample. These element sensitive contrast variations can be used to analyse average composition fluctuations on the nm scale. Two kinds of nanoparticles are chosen here to elaborate the advantages of ASAXS in the analysis of complex materials. A facile and efficient methodology is developed for the thermal synthesis of size-tunable, stable, and uniform bimetallic NiCu core–shell nanoparticles (NPs) for various application in catalysis. Their diameter can be tuned in a range from 6 nm to 30 nm and the Ni:Cu ratio is adjustable in a wide range from 1:1 to 30:1. The NPs are structurally characterized by a method combination of transmission electron microscopy, anomalous small-angle X-ray scattering (ASAXS), X-ray absorption fine structure, and X-ray photoelectron spectroscopy. Here, we focus on the ASAXS method and its ability to analyses nanostructure parts and their compositions at once. As a result, a NiCu alloyed core surrounded by a Ni enriched shell and an outer NiO shell was found. Semiconductor nanocrystals (quantum dots, QDs) are well known for their superior photophysical properties and enabled advancements in several key technologies of the 21st century and numerous technological applications like in photovoltaics, LED displays, photocatalysis, and biosensing. To achieve high photoluminescence quantum yields (PLQY) and enhanced photostability the QD core needs to be passivated by a second semiconductor, which possess a larger band gap to confine the charges within the QD core. An important parameter is thereby the lattice mismatch between the core and shell. To avoid strong lattice strain, which would alter the photophysical properties, an intermediary shell can be used as a lattice adapter between the core and the outer shell leading to core/shell/shell systems. These systems have shown to possess high PLQYs combined with a strong long-term stability and can be found in modern QLED displays. ASAXS was used here to better understand the core/shell/shell structure of InP/ZnSe/ZnS QDs to enable a correlation between their structural and photophysical properties. T2 - IUCr - International Union of Crystallography CY - Melbourne, Australia DA - 22.08.2023 KW - ASAXS KW - Quantum dot KW - Core/shell materials KW - Safer by design PY - 2023 AN - OPUS4-58812 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reichelt, Manuel A1 - Cappella, Brunero T1 - Micro- and nanowear of self-mated steel generated and studied with an AFM at the single asperity level N2 - We show for the first time tribotests performed with self-mated 100Cr6 steel, taking advantage of an AFM, employed as a tribometer for the tribotests as well as for the inspection of wear of both tribopartners. Emphasis is put on the morphology of the scars, on wear particles, and on wear of the “colloidal” particles glued on the AFM cantilever. Measurements demonstrate the possibility of characterizing single asperity events leading to very small wear. We highlight several phenomena, which are elementary key constituents of tribological processes. Such phenomena, probably occurring also at the macroscale, can be detected, identified, and characterized with high spatial and time resolution only at the nanoscale, thus giving insight into conditions and causes of their emergence. KW - Nanowear KW - Atomic force microscope KW - 100Cr6 (AISI 52100) steel KW - Wear particles KW - Single asperity contact KW - Particle transfer KW - Zero wear PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531389 DO - https://doi.org/10.3389/fmech.2021.722434 SN - 2297-3079 VL - 7 SP - 1 EP - 16 PB - Frontiers Media CY - Lausanne AN - OPUS4-53138 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, P. A1 - Ihlemann, J. A1 - Bonse, Jörn T1 - Editorial: Special issue "Laser-generated periodic nanostructures" N2 - The study of laser-fabricated periodic nanostructures is one of the leading topics of today’s photonics research. Such structures on the surface of metals, semiconductors, dielectrics, or polymers can generate new material properties with special functionalities. Depending on the specific material parameters and the morphology of the structures, new devices such as microlasers, optical nanoswitches, optical storage devices, sensors or antifraud features can be realized. Furthermore, laser-generated surface textures can be used to improve the tribological properties of surfaces in contact and in relative motion—to reduce friction losses or wear, to modify the wettability or the cell and biofilm growth properties of surfaces through bioinspired laser engineering, for emerging medical applications, or as decoration elements for the refinement of precious goods. This Special Issue “Laser-Generated Periodic Nanostructures” focuses on the latest experimental and theoretical developments and practical applications of laser-generated periodic structures that can be generated in a “self-organized” way (laser-induced periodic surface structures, LIPSS, ripples) or via laser interference-based direct ablation (often referred to as direct laser interference patterning, DLIP). We aimed to attract both academic and industrial researchers in order to collate the current knowledge of nanomaterials and to present new ideas for future applications and new technologies. By 8 August 2021, 22 scientific articles have been published in the Special Issue, see www.mdpi.com/journal/nanomaterials/special_issues/laser-generated_periodic. KW - Laser-induced periodic surface structures (LIPSS) KW - Direct laser interference patterning (DLIP) KW - Surface functionalization KW - Laser ablation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-530980 DO - https://doi.org/10.3390/nano11082054 SN - 2079-4991 VL - 11 IS - 8 SP - 1 EP - 7 PB - MDPI CY - Basel AN - OPUS4-53098 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Sebastian A1 - Cappella, Brunero T1 - Friction and mechanical properties of AFM-scan-induced ripples in polymer films N2 - In the present paper, friction and mechanical properties of AFM-Scan-Induced ripple structures on films of polystyrene and poly-n-(butyl methacrylate) are investigated. Force volume measurements allow a quantitative analysis of the elastic moduli with nanometer resolution, showing a contrast in mechanical response between bundles and troughs. Additionally, analysis of the lateral cantilever deflection shows a clear correlation between friction and the sample topography. Those results support the theory of crack propagation and the formation of voids as a mechanism responsible for the formation of ripples. This paper also shows the limits of the presented measuring methods for soft, compliant, and small structures. KW - AFM KW - Polymer KW - Ripples KW - Mechanical properties KW - Friction PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-532772 DO - https://doi.org/10.3389/fmech.2021.672898 SN - 2297-3079 VL - 7 SP - 1 EP - 8 PB - Frontiers Media CY - Lausanne AN - OPUS4-53277 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Omar, Hassan T1 - Growth Kinetics and Molecular Mobility of the Adsorbed Layer of Poly(bisphenol-A Carbonate) (PBAC), Polysulfone (PSU), and Poly (2-Vinyl Pyridine) (P2VP) N2 - Interactions between a polymer and a substrate interface play a vital role in understanding the improvement in thin film material properties as well as serving as a model for nanocomposites. For any non-repulsive polymer-substrate interactions, polymer segments form an irreversibly adsorbed layer and show a slowdown in the glassy dynamics and thus an increase in the thermal glass transition temperature compared to the bulk-like values. The growth kinetics of the adsorbed layer showed a deviation for both poly (bisphenol-A carbonate) (PBAC) and polysulfone (PSU), two bulky polymers containing a functional group (phenyl ring) in the backbone, compared to conventional polymers previously studied like poly-2-vinyl pyridine (P2VP). This deviation was attributed to the bulkiness of the phenyl rings. . Further investigations into the influence of the adsorbed layer on glassy dynamics were conducted. The molecular mobility and glass transition for thin films of PBAC and PSU were compared to bulk samples of each polymer. Broadband dielectric spectroscopy, atomic force microscopy, and ellipsometry were primarily used and additionally supported by sum frequency generation spectroscopy. T2 - Deutsche Physikalische Gesellschaft (DPG) Tagung CY - Berlin, Germany DA - 17.03.2024 KW - Thin films KW - Adsorbed Layer KW - Atomic Force Microscopy KW - Ellipsometry KW - Dielectric Spectroscopy PY - 2024 AN - OPUS4-59821 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Gräf, S. T1 - Ten Open Questions about Laser-Induced Periodic Surface Structures N2 - Laser-induced periodic surface structures (LIPSS) are a simple and robust route for the nanostructuring of solids that can create various surface functionalities featuring applications in optics, medicine, tribology, energy technologies, etc. While the current laser technologies already allow surface processing rates at the level of m2/min, industrial applications of LIPSS are sometimes hampered by the complex interplay between the nanoscale surface topography and the specific surface chemistry, as well as by limitations in controlling the processing of LIPSS and in the long-term stability of the created surface functions. This Perspective article aims to identify some open questions about LIPSS, discusses the pending technological limitations, and sketches the current state of theoretical modelling. Hereby, we intend to stimulate further research and developments in the field of LIPSS for overcoming these limitations and for supporting the transfer of the LIPSS technology into industry. KW - Laser-induced periodic surface structures (LIPSS) KW - Industrial application KW - Functional properties KW - Surface functionalization KW - Modelling PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539503 DO - https://doi.org/10.3390/nano11123326 SN - 2079-4991 VL - 11 IS - 12 SP - 1 EP - 21 PB - MDPI CY - Basel, Switzerland AN - OPUS4-53950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lindemann, Franziska T1 - Bestimmung der spezifischen Oberfläche mittels Gasadsorption (BET-Verfahren) N2 - Im Rahmen des 2. BAM-Akademie Info-Tages "Nano or not Nano" wurde die OECD TG 124 "Volume Specific Surface Area of Manufactured Nanomaterials" vorgestellt. Der Vortrag beschreibt die Bestimmung der spezifischen Oberfläche von dispersen und/oder porösen Pulvern mittels Gasadsorption nach dem BET-Verfahren. Es wird auf die Anwendbarkeit der Methode eingegangen und es werden praktische Hinweise zur Probenvorbereitung und Messung von Nanomaterialien gegeben. T2 - BAM Akademie II: Info-Tage "Nano or not Nano" CY - Online meeting DA - 25.01.2024 KW - OECD TG 124 KW - Nanopulver KW - VSSA KW - Nano powder KW - BET KW - Spezifische Oberfläche PY - 2024 AN - OPUS4-59623 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -