TY - CONF A1 - Florian, Camilo A1 - Deziel, J.-L. A1 - Kirner, Sabrina V. A1 - Siegel, J. A1 - Bonse, Jörn T1 - Femtosecond laser-induced oxidation in the formation of periodic surface structures N2 - Micro- and nanostructuring with laser-induced periodic surface structures (LIPSS) has been demonstrated to be feasible in a wide variety of materials including metals, semiconductors and dielectrics. Suitable processing regimes for flat, curved and complex surfaces have been identified for many materials, allowing the generation of diverse applications in fields such as optics, tribology and medicine, to name a few. A common side effect when producing such structures in air environment is the formation of a thin surface oxide layer in the laser irradiated areas. Previous studies have shown that oxidation plays an important role in the tribological performance for which the structures where created, and very recently it has been shown that the laser-induced oxide graded layers may contribute to the formation of a new type of embedded low-spatial frequency LIPSS (LSFL) with annomalous orientation parallel to the laser polarization, in addition to the appearance of the well-known high-spatial frequency LIPSS (HSFL) at the surface. In this contribution, we explore this effect experimentally for chromium nitride (CrN) irradiated with femtosecond laser pulses and compare the findings to finite-difference time-domain (FDTD) simulations of the intensity distributions at different depth positions. T2 - 2021 Conference on Lasers and Electro-Optics/Europe – European Quantum Electronics Virtual Conferences CY - Munich, Germany DA - 21.06.2021 KW - Femtosecond laser ablation KW - Finite-difference time-domain calculations KW - Laser-induced periodic surface structures (LIPSS) KW - Surface oxidation PY - 2021 SN - 978-1-6654-1876-8 U6 - https://doi.org/10.1109/CLEO/Europe-EQEC52157.2021.9542774 VL - 2021 SP - 1 PB - Institute of Electrical and Electronics Engineers (IEEE) CY - Piscataway, NJ, USA AN - OPUS4-53457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmid, M. A1 - Heidmann, B. A1 - Ringleb, F. A1 - Eylers, K. A1 - Ernst, O. A1 - Andree, Stefan A1 - Bonse, Jörn A1 - Boeck, T. A1 - Krüger, Jörg T1 - Locally grown Cu(In,Ga)Se2 micro islands for concentrator solar cells N2 - Light concentration opens up the path to enhanced material efficiency of solar cells via increased conversion efficiency and decreased material requirement. For true material saving, a fabrication method allowing local growth of high quality absorber material is essential. We present two scalable fs-laser based approaches for bottom-up growth of Cu(In,Ga)Se2 micro islands utilizing either site-controlled assembly of In(,Ga) droplets on laser-patterned substrates during physical vapor deposition, or laser-induced forward transfer of (Cu,In,Ga) layers for local precursor arrangement. The Cu(In,Ga)Se2 absorbers formed after selenization can deliver working solar devices showing efficiency enhancement under light concentration. T2 - SPIE OPTO, 2018 CY - San Francisco, USA DA - 29.01.2018 KW - Chalcopyrite KW - Cu(In,Ga)Se2 KW - Fs-laser patterning KW - Laser-induced forward transfer KW - Micro solar cell PY - 2018 SN - 978-1-5106-1540-3 SN - 0277-786X SN - 1996-756X VL - 10527 SP - 1052707-1 EP - 1052707-9 PB - SPIE CY - Bellingham, WA, USA AN - OPUS4-44450 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stajanca, Pavol A1 - Topolniak, Ievgeniia A1 - Pötschke, Samuel A1 - Krebber, Katerina ED - Kalli, K. ED - Mendez, A. ED - Bunge, C.-A. T1 - Solution doping of commercial plastic optical fibers N2 - Solution doping of off-the-shelf plastic optical fibers (POFs) represents rather simple and cheap way for preparing custom cladding-doped POFs (CD-POFs) with short to medium lengths. CD-POFs are especially attractive for environmental sensing applications, but might be of interest for illumination task as well. In this work, the proposed doping technique is tested with three different commercial low-cost polymethyl methacrylate (PMMA) POFs; Eska CK-40 and Eska GK-40 from Mitsubishi Rayon and Raytela PGU-FB1000 from Toray. The aim of the work is to aid the selection of the most suitable fiber yielding highest optical quality of prepared CD-POFs. Firstly, the optimal doping times are determined for the individual fiber types using short fiber samples. Secondly, longer 10 m CD-POFs are prepared from all tested fibersusing the optimized doping procedure. Finally, attenuation of pristine POFs and prepared CD-POFs is measured using optical time domain reflectometry in order to characterize the impacts of the doping on fiber optical properties. In addition, the importance of post-doping drying procedure for CD-POF optical performance is investigated as well. The results suggest that, although doping of all tested fibers is generally feasible, Eska CK-40 is the most suitable candidate with regard to the Doping efficiency and fiber post-doping performance. T2 - SPIE Photonics Europe 2018 CY - Strasbourg, France DA - 22.04.2018 KW - Plastic optical fibers KW - Solution doping KW - Polzmethyl methacrylate KW - PMMA KW - Rhodamine B KW - Fluorescent optical fibers KW - Cladding-doped fibers PY - 2018 U6 - https://doi.org/10.1117/12.2315619 SN - 0277-786X VL - 10681 SP - 106810O-1 EP - 106810O-7 AN - OPUS4-44907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor A1 - Sturm, Patrick A1 - Greiser, Sebastian A1 - Jäger, Christian A1 - Kühne, Hans-Carsten ED - Wang, J. ED - Kriven, W. ED - Fey, T. ED - Colombo, P. ED - Weber, W.J. ED - Amoroso, J. ED - Fahrenholtz, W.G. ED - Shimamura, K. ED - Halbig, M. ED - Kirihara, S. ED - Wu, Y. ED - Shurgart, K. T1 - One-part geopolymers and aluminosilicate gel-zeolite composites: factors influencing microstructure and engineering properties N2 - Mixing and curing of geopolymers and related alkali-activated materials without storage and handling of highly alkaline solutions possesses advantages regarding safety and economic viability. One possible approach is to produce these materials from solid silica feedstocks and solid sodium aluminate, and subsequent mixing with water. We present a comparison between geopolymers and aluminosilicate gel-zeolite composites synthesized by this route from different silica feedstocks (by-product silica from chlorosilane production, microsilica, rice husk ash) and with different SiO2/Al2O3 ratios, using results from XRD, NMR, SEM, thermal analysis, mechanical and acid resistance testing. The use of rice husk ash favors formation of a fully amorphous geopolymer with high strength. Utilization of the other silica feedstocks leads to formation of aluminosilicate gel-zeolite composites, the amount and kind of zeolites depending on the feedstock and the SiO2/Al2O3 ratio. These composites show beneficial dehydration behavior, viz. no distinct dehydration step of thermal strain, with the phase assemblage after heating to 1000°C controlled by the starting composition. Mortars produced from both, the geopolymers as well as the composites, exhibit high resistance to sulfuric acid attack, making them promising materials for the construction and the repair of industrial and sewer structures. T2 - 42nd International Conference on Advanced Ceramics and Composites CY - Daytona Beach, FL, USA DA - 21.01.2018 KW - Alkali-activated materials KW - One-part geopolymers KW - Sulfuric acid resistance KW - High-temperature resistance PY - 2019 U6 - https://doi.org/10.1002/9781119543381.ch17 VL - 39 IS - 3 SP - 183 EP - 196 PB - John Wiley & Sons AN - OPUS4-47282 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - X-ray emission during ultrashort pulse laser processing N2 - The industrial use of ultrashort laser pulses has made considerable progress in recent years. The reasons for this lie in the availability of high average powers at pulse repetition rates in the several 100 kHz range. The advantages of using ultrashort laser pulses in terms of processing precision can thus be fully exploited. However, high laser intensities on the workpiece can also lead to the generation of unwanted X-rays. Even if the emitted X-ray dose per pulse is low, the accumulated X-ray dose can become significant for high-repetition-rate laser systems so that X-ray exposure safety limits must be considered. The X-ray emission during ultrashort pulse laser processing was investigated for a pulse duration of 925 fs at 1030 nm wavelength and 400 kHz repetition rate. Industrially relevant materials such as steel,aluminum and glass were treated. Tungsten served as reference. X-ray spectra were recorded, and X-ray dose measurements were performed for laser treatment in air. For laser intensities > 2 × 10^13 W/cm2, X-ray doses exceeding the regulatory exposure limits for members of the public were found. Suitable X-ray protection strategies are proposed. T2 - SPIE Photonics West CY - San Francisco, USA DA - 02.02.2019 KW - Laser-induced X-ray emission KW - Ultrashort laser material interaction KW - Radiation protection PY - 2019 SN - 978-1-5106-2459-7 U6 - https://doi.org/10.1117/12.2516165 SN - 0277-786X SN - 1996-756X VL - 10908 SP - 1090802-1 EP - 1090802-7 PB - SPIE - The international society for optics and photonics CY - Bellingham, WA, USA AN - OPUS4-47510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bauer, J. A1 - Miclea, P.-T. A1 - Braun, U. A1 - Altmann, Korinna A1 - Turek, M. A1 - Hagendorf, C. T1 - Microplastic detection and analysis in water samples N2 - Microplastic detection in water samples becomes important for tracing microplastic sources. Microplastic may harm desalination facilities by blocking filters and disturbing the marine food chain. Thermo analytical methods such as pyrolysis gas chromatography mass spectroscopy, and spectroscopic methods like (micro) Raman spectroscopy or (micro) Fouriertransform infrared spectroscopy in combination with appropriate filters and sample preparation are suitable for analyzing microplastics on a scale from 1 µm to 1000 µm fast and unambiguous. While the thermo analytical methods are suitable for larger sample volumes, Raman spectroscopy and Fouriertransform infrared spectroscopy are able to detect and analyze single microplastic particles for instance in bottled water. Machine learning algorithms ensure a reliable classification of different plastic materials. T2 - International Conference on Sustainable Energy-Water-Environment Nexus in Desert Climate 2019 CY - Ar-Rayyan, Qatar DA - 02.12.2019 KW - Microplastics KW - Water samples PY - 2022 SP - 111 EP - 113 PB - Springer AN - OPUS4-56240 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhsler, Andreas A1 - Sobol, Oded A1 - Nolze, Gert A1 - Unger, Wolfgang A1 - Böllinghaus, Thomas T1 - Use of time-of-flight secondary ion mass spectrometry for the investigation of hydrogen-induced effects in austenitic steel AISI 304L N2 - During the energy transformation from fossil fuels to renewable energy sources, the use of hydrogen as fuel and energy storage can play a key role. This presents new challenges to industry and the scientific community alike. The storage and transport of hydrogen, which is nowadays mainly realized by austenitic stainless steels, remains problematic, which is due to the degradation of mechanical properties and the possibility of phase transformation by hydrogen diffusion and accumulation. The development of materials and technologies requires a fundamental understanding of these degradation processes. Therefore, studying the behavior of hydrogen in austenitic steel contributes to an understanding of the damage processes, which is crucial for both life assessment and safe use of components in industry and transportation. As one of the few tools that is capable of depicting the distribution of hydrogen in steels, time-of-flight secondary ion mass spectrometry was conducted after electrochemical charging. To obtain further information about the structural composition and cracking behavior, electron-backscattered diffraction and scanning electron microscopy were performed. Gathered data of chemical composition and topography were treated employing data fusion, thus creating a comprehensive portrait of hydrogen-induced effects in the austenite grade AISI 304L. Specimens were electrochemically charged with deuterium instead of hydrogen. This arises from the difficulties to distinguish between artificially charged hydrogen and traces existing in the material or the rest gas in the analysis chamber. Similar diffusion and permeation behavior, as well as solubility, allow nonetheless to draw conclusions from the experiments. T2 - 21st International Conference on Secondary Ion Mass Spectrometry CY - Kraków, Poland DA - 10.09.2017 KW - AISI 304L KW - Hydrogen KW - ToF-SIMS KW - Austenitic stainless steel PY - 2018 U6 - https://doi.org/10.1116/1.5013931 SN - 1071-1023 VL - 36 IS - 3 SP - Article 03F103, 1 EP - 6 PB - American Vacuum Society (AVS) AN - OPUS4-44840 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -