TY - JOUR A1 - Wissel, Julian A1 - Freudenmann, Dominic A1 - Cichocka, Magdalena Ola A1 - Pöhl, Almut A1 - Stephan-Hofmann, Iris A1 - Röcke, Nicole A1 - Pérez, Nicolás A1 - Döhring, Thorsten A1 - Stadtmüller, Johannes A1 - Stollenwerk, Manfred T1 - Microstructure of highly effective platinum–iridium alloys as catalysts for hydrogen peroxide decomposition JF - Research on Chemical Intermediates KW - Iridium KW - Katalysator KW - Raumfahrttechnik KW - Antrieb, Technik KW - Wasserstoffperoxyd Y1 - 2024 U6 - https://doi.org/10.1007/s11164-024-05412-4 SN - 0922-6168 VL - 50 IS - 11 SP - 5385 EP - 5397 PB - Springer Science and Business Media LLC ER - TY - JOUR A1 - Amorim, Isilda A1 - Spera, Natalia C.M. A1 - Nicoara, Nicoleta A1 - Ramasamy, Devaraj A1 - Alves, Diana F. A1 - Stollenwerk, Manfred A1 - Stadtmüller, Johannes A1 - Döhring, Thorsten A1 - Sadewasser, Sascha A1 - Kolen'ko, Yury V. A1 - Sousa, Juliana P.S. T1 - Overall alkaline water electrolysis over active, stable, low loading iridium catalysts sputtered on nickel foam JF - International Journal of Hydrogen Energy KW - Iridium KW - Katalysator KW - Wasserstoffelektrolyse KW - Wasser KW - Elektrolyse KW - Wasserstofferzeugung Y1 - 2024 U6 - https://doi.org/10.1016/j.ijhydene.2024.10.306 SN - 0360-3199 VL - 92 SP - 852 EP - 864 PB - Elsevier BV ER - TY - JOUR A1 - Schmitt, Paul A1 - Felde, Nadja A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Uschmann, Ingo A1 - Hanemann, Kevin A1 - Siegler, Marie A1 - Klemm, Georg A1 - Gratzke, Nancy A1 - Tünnermann, Andreas A1 - Schwinde, Stefan A1 - Schröder, Sven A1 - Szeghalmi, Adriana T1 - Optical, structural, and functional properties of highly reflective and stable iridium mirrorcoatings for infrared applications: supplement JF - Optical Materials Express N2 - Metallic coatings are essential for numerous optical systems due to their high and broadband refl ectivity in the infrared spectral range. In contrast to well-established (protected)silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally,the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI, AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings diff er due to their topography and microstructure. KW - Iridium KW - mirror KW - ALD KW - Sputter KW - Iridium KW - Beschichtung Y1 - 2022 U6 - https://doi.org/10.6084/m9.figshare.17121509 VL - 2022 IS - 12/2 SP - 545 EP - 559 ER - TY - JOUR A1 - Schmitt, Paul A1 - Felde, Nadja A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred A1 - Uschmann, Ingo A1 - Hanemann, Kevin A1 - Siegler, Marie A1 - Klemm, Georg A1 - Gratzke, Nancy A1 - Tünnermann, Andreas A1 - Schwinde, Stefan A1 - Schröder, Sven A1 - Szeghalmi, Adriana T1 - Optical, structural, and functional properties of highly reflective and stable iridium mirror coatings for infrared applications JF - Optical Materials Express N2 - Metallic coatings are essential for numerous optical systems due to their high and broadband refl ectivity in the infrared spectral range. In contrast to well-established (protected)silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally,the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI,AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings diff er due to their topography and microstructure. KW - Iridium KW - mirror KW - Sputter KW - ALD KW - Iridium KW - Beschichtung Y1 - 2022 U6 - https://doi.org/10.1364/OME.447306 VL - 2022 IS - 12 / 2 SP - 545 EP - 559 ER - TY - JOUR A1 - Döhring, Thorsten ED - IHK Aschaffenburg, T1 - Forscher entwickeln umweltfreundliche Satellitenantriebe JF - Wirtschaft am Bayerischen Untermain N2 - In der aktuellen Förderrunde des vom Bayerischen Staatsministeriums für Wissenschaft und Kunst aufgesetzten „Programms zur Förderung der angewandten Forschung und Entwicklung an Hochschulen für angewandte Wissenschaften – Fachhochschulen“ war die Technische Hochschule Aschaffenburg sehr erfolgreich. Für das Technologieprojekt ACCASI („Aschaffenburg Competence Center for Astronomical and Space Instrumentation“) erhält sie über eine Laufzeit von drei Jahren insgesamt 250.000 Euro. KW - Satellit KW - Triebwerk KW - Iridium KW - Katalysator KW - Satellitentechnik Y1 - 2021 UR - https://www.aschaffenburg.ihk.de/share/flipping-book/5064860/flippingbook.pdf VL - 2021 IS - März SP - 12 EP - 13 ER - TY - JOUR A1 - Stollenwerk, Manfred A1 - Döhring, Thorsten A1 - Freudenmann, Dominic A1 - Schäfer, Tobias A1 - Stadtmüller, Johannes A1 - Röcke, Nicole T1 - Sputtered highly effective iridium catalysts: a new approach for green satellite propulsion JF - Journal of Materials Science N2 - This work demonstrated the large potential of sputtered iridium metal for catalytic reactions shown by the example of decomposition of hydrogen peroxide (H2O2) for space propulsion systems. For this purpose, iridium was coated onto Al2O3 pellets by a sputter process under varied process parameters. Depending on previously selected parameters, the obtained metal-loaded pellets offer closed- and/or open-shell structures. Catalytic productivity of these first-generation iridium-sputtered catalysts was estimated in laboratory experiments and compared to platinum-loaded pellets. Under optimized sputter-process conditions, the reactivity is significantly improved compared to the platinum-impregnated pellets. The better catalytic productivity can be explained by the increased active surface area of the iridium layers on the pellets. The surface morphology and the microstructure of the iridium coating can be actively controlled by the sputter pressure. The results are in accordance with the sputtering process pressure tendency described by the Thornton Structure–Zone Model. KW - Iridium KW - Katalysator KW - Satellitentechnik Y1 - 2021 U6 - https://doi.org/https://doi.org/10.1007/s10853-021-05897-z VL - 2021 IS - 2021 SP - 1 EP - 11 ER - TY - JOUR A1 - Probst, Anne-Catherine A1 - Begou, Thomas A1 - Döhring, Thorsten A1 - Zeising, Sebastian A1 - Stollenwerk, Manfred A1 - Stadtmüller, Johannes A1 - Emmerich, Florian A1 - Lumeau, Julien ED - Publishing OSA, T1 - Coating stress analysis and compensation for iridium-based x-ray mirrors JF - Applied Optics N2 - Iridium-based coatings for mirrors of x-ray telescopes are studied. In particular, stress-induced deformation is characterized and shown to be compressive and equal to −1786  MPa. Two methods for stress compensation are then studied. One relies on the deposition of silica on the back surface of the substrate and a second one relies on the deposition of a chromium sublayer. Advantages and drawbacks of each of these techniques are presented. KW - iridium KW - coating stress KW - X-ray KW - mirror KW - astronomy KW - Röntgenteleskop KW - Iridium KW - Spiegelteleskop Y1 - 2018 UR - https://doi.org/10.1364/AO.57.008775 VL - 2018 IS - 57 (29) SP - 8775 EP - 8779 ER - TY - JOUR A1 - Probst, Anne-Catherine A1 - Stollenwerk, Manfred A1 - Emmerich, Florian A1 - Büttner, Andre A1 - Zeising, Sebastian A1 - Stadtmüller, Johannes A1 - Riethmüller, Franziska A1 - Stehlikova, Veronika A1 - Mingwu, Wen A1 - Proserpio, Laura A1 - Damm, Christine A1 - Rellinghaus, Bernd A1 - Döhring, Thorsten T1 - Influence of sputtering pressure on the nanostructure and the X-ray reflectivity of iridium coatings JF - Surface and Coatings Technology N2 - Reflective mirror coatings made of iridium are used in X-ray telescopes of the Chandra X-ray Observatory (CXO) launched in 1999 by the National Aeronautics and Space Administration (NASA) to investigate astronomical sources at photon energies below 10. keV. These coatings were produced in a DC magnetron sputtering process and have so far proven their suitability for space-based applications. We are considering in the present paper the processing of thin iridium films for lightweight telescopes using the radio frequency magnetron sputtering technique with an oblique angle deposition. The coating development presented here is focused on the influence of total sputtering pressure on film properties as well as on its impact on the mirror's performance. Characterisation methods such as X-ray diffractometry, X-ray reflectometry, atomic force microscopy and transmission electron microscopy have been used. Correlations between morphology, density, surface micro-roughness, crystal structure of the iridium layer and the expected reflectivity of the X-ray mirror are described and discussed. KW - Iridium KW - sputtering KW - microstructure KW - coating KW - X-ray KW - Iridium KW - Röntgenteleskop Y1 - 2017 UR - https://doi.org/10.1016/j.surfcoat.2017.10.062 SN - 0257-8972 VL - 2017 IS - 343 SP - 101 EP - 107 ER - TY - JOUR A1 - Büttner, Andre A1 - Probst, Anne-Catherine A1 - Emmerich, Florian A1 - Damm, Christine A1 - Rellinghaus, Bernd A1 - Döhring, Thorsten A1 - Stollenwerk, Manfred T1 - Influence of Sputtering Pressure on the Microstructure and Layer Properties of Iridium Thin Films JF - Thin Solid Films N2 - Iridium layers with low stress, high density, and low surface roughness find widespread use in different high-technology applications. This paper presents a study of the influence of the sputtering pressure on the properties of iridium thin films and of its effect on the substrate surface microstructure. We analysed the dependence of the microstructure, crystalline structure, electrical resistivity, and deposition rate on the sputtering pressure and surface defects of the substrate. For the latter, plasma etching of the substrate was performed for different processing times and its effect on the surface roughness of substrates and, subsequently, on the grown iridium films, was examined. The sputtering pressure and the substrate plasma etching time both had a strong influence on the microstructure and surface roughness. These microstructural changes are in good agreement with the tendency described in the Thornton Structure-Zone Model for different sputtering pressures and the microstructure phase map of Alvarez. The electrical resistivity, deposition rate, and crystalline structure were highly dependent on the sputtering pressure. KW - Iridium KW - microstructure KW - TEM KW - sputtering KW - thin films KW - Iridium KW - Dünne Schicht Y1 - 2018 UR - https://doi.org/10.1016/j.tsf.2018.06.056 SN - 0040-6090 VL - 2018 IS - 662 SP - 41 EP - 46 ER - TY - JOUR A1 - Stehlikova, Veronika A1 - Probst, Anne-Catherine A1 - Nentvich, Ondrej A1 - Urban, Martin A1 - Sieger, Ladislav A1 - Döhring, Thorsten A1 - Hudec, René ED - Skopal, Augustín T1 - Study of multiple layers coatings for X–ray mirrors JF - Contributions of the Astronomical Observatory Skalnaté Pleso N2 - This paper focuses on a theoretical background that motivated the experimental campaign of multiple layer coatings of X-ray mirrors, and the first results of the testing of the prepared samples. Simulations of the use of different overcoats were performed in order to improve the reflectivity of thin iridium coatings designed for X-ray optics effective in the energy up to 10 keV. Samples based on these simulations were prepared and are being tested for the properties that influence the X-ray optical performance, such as layer homogeneity, density and surface micro-roughness. Further the topic of the coating stress was addressed, as it is an issue in case of thin, lightweight X-ray mirrors and affects the time stability of layers. The discussion and preliminary results conclude our contribution. KW - X-ray KW - optics KW - coating KW - reflectivity KW - iridium KW - Röntgenspiegel KW - Iridium Y1 - 3018 UR - https://www.ta3.sk/caosp/Eedition/Abstracts/2018/Vol_48/No_3/pp488-497_abstract.html VL - 2018 IS - 48 SP - 488 EP - 497 ER - TY - JOUR A1 - Döhring, Thorsten A1 - Hudec, Rene ED - Skopal, Augustín T1 - JEUMICO and TRILAMICO: Dimensions of successful Bavarian-Czech cooperation JF - Contributions of the Astronomical Observatory Skalnaté Pleso N2 - In December 2017 the two projects JEUMICO (an acronym for Joint European Mirror Cooperation) and TRILAMICO (standing for Trilateral Mirror Collaboration) are ending. Different aspects of this Bavarian-Czech collaboration between Aschaffenburg University and the Czech Technical University in Prague are discussed. The multiple dimensions of this cooperation are scientific achievements, public relation measures, internationalization of education, financial aspects, inter-cultural communication, and also the actual political situation within Europe. KW - JEUMICO KW - TRILAMICO KW - BTHA KW - Iridium KW - astronomy KW - Röntgenspiegel KW - Spiegelteleskop Y1 - 2018 UR - https://www.astro.sk/caosp/Eedition/Abstracts/2018/Vol_48/No_3/pp430-436_abstract.html VL - 2018 IS - Vol. 48 / 3 SP - 430 EP - 436 ER - TY - JOUR A1 - Hudec, Rene A1 - Döhring, Thorsten ED - Slovak Academy of Sciences Astronomical Institute, T1 - JEUMICO: Czech-Bavarian astronomical X-ray optics project JF - Contributions of the Astronomical Observatory Skalnaté Pleso N2 - Within the project JEUMICO, an acronym for Joint European Mirror Competence, the Aschaffenburg University of Applied Sciences and the Czech Technical University in Prague started a collaboration to develop mirrors for X-ray telescopes. Corresponding mirror segments use substrates of at silicon wafers which are coated with thin iridium � lms, as this material is promising high re ectivity in the X-ray range of interest. The sputtering parameters are optimized in the context of the expected re ectivity of the coated X-ray mirrors. In near future measurements of the assembled mirror modules optical performances are planned at an X-ray test facility. KW - JEUMICO KW - astronomy KW - mirror KW - iridium KW - Iridium KW - Spiegelteleskop Y1 - 2017 UR - https://www.ta3.sk/caosp/Eedition/Abstracts/2017/Vol_47/No_2/pp170-177_abstract.html VL - 2017 IS - 47 SP - 170 EP - 177 ER -