TY - JOUR A1 - Wollschläger, Nicole A1 - Tasdemir, Z. A1 - Häusler, Ines A1 - Leblebici, Y. A1 - Österle, Werner A1 - Alaca, B. E. T1 - Determination of the elastic behavior of silicon nanowires within a scanning electron microscope JF - Journal of Nanomaterials N2 - Three-point bending tests were performed on double-anchored, <110> silicon nanowire samples inside a scanning electron microscope (SEM) via a micromanipulator equipped with a piezo-resistive force sensor. Representing the upper and lower boundaries achievable in a consistent manner, silicon nanowires with widths of 35 nm and 74 nm and a height of 168 nm were fabricated. The nanowires were obtained monolithically along with their 10-m-tall supports through a top-down fabrication approach involving a series of etching processes. Hence, no interface compliance was introduced between supports and nanowires. Exact nanowire dimensions and cross-sectional features were determined by transmission electron microscopy (TEM) following sample preparation through focused ion beam (FIB) machining. Conducting the experiments inside an SEM chamber further raised the opportunity of the direct observation of any deviation from ideal loading conditions such as twisting, which was taken into consideration in simulations. Measured force-displacement behavior was observed to exhibit close resemblance to simulation results obtained by finite element modeling, when the bulk value of 169 GPa was taken as the modulus of elasticity for <110> silicon. Hence, test results show neither any size effect nor evidence of residual stresses for the considered nanoscale objects. The increased effect of the native oxide with reduced nanowire dimensions was captured as well. Thus this very simple in-situ testing method was found to be an alternative to elaborate AFM measurements on geometrically formidable nanostructures. The results demonstrate the applicability of the developed fabrication approach to the incorporation of silicon nanowires in functional micromechanical devices. KW - Silicon nanowire KW - Elastic behavior KW - Scanning electron microscope KW - Mechanical properties PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-370383 DO - https://doi.org/10.1155/2016/4905838 VL - 2016 SP - Article 4905838, 1 EP - 6 PB - Hindawi Publishing Corporation AN - OPUS4-37038 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ortel, Erik A1 - Häusler, Ines A1 - Österle, Werner A1 - Narbey, S. A1 - Oswald, F. A1 - Andersen, I. H. A1 - Holzweber, Markus A1 - Unger, Wolfgang A1 - Hodoroaba, Vasile-Dan T1 - In-depth structural and chemical characterization of engineered TiO2 films JF - Surface and Interface Analysis N2 - Analytical routines for a comprehensive in-depth morphological, structural, and chemical characterization of functionalized TiO2 films by using different state-of-the-art analytical techniques are presented and discussed with the main objective to identify potential reference TiO2 coating parameters able to be certified at a later stage. TiO2 films fabricated by two different synthetic procedures as representative for two main large-scale applications were selected: (i) pulsed d.c. magnetron sputtering for photocatalytic applications and (ii) screen printing from preformed anatase nanoparticles. The screen-printed films were further loaded with a sensitizing dye for application as a dye-sensitized solar cell. Film properties such as microstructure and crystallographic texture of pulsed d.c. magnetron sputtering synthesized films were systematically studied by means of scanning nanobeam electron diffraction in a transmission electron microscope and the surface and inner morphology by scanning electron microscopy. The dye distribution over the depth of screen-printed TiO2 layers was analyzed before and after dye-loading by means of energy dispersive X-ray spectroscopy at scanning electronmicroscope, Auger electron spectroscopy and time-of-flight secondary ion mass spectrometry. The long-term goal of the present study is the improvement of quality of the TiO2 film parameters as measured by using different types of reference TiO2 coatings having specific parameters certified. T2 - 16th European Conference on Applications of Surface and Interface Analysis ECASIA'15 CY - Granada, Spain DA - 28.09.2015 KW - Mapping KW - Line scan KW - Depth profiling KW - TiO2 films KW - Crystallinity KW - Ru dye sensitizer PY - 2016 DO - https://doi.org/10.1002/sia.5966 SN - 0142-2421 SN - 1096-9918 VL - 48 SP - 664 EP - 669 PB - John Wiley & Sons, Ltd. AN - OPUS4-36791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, G. A1 - Österle, Werner A1 - Jim, B. A1 - Häusler, Ines A1 - Hesse, Rene A1 - Wetzel, B. T1 - The role of surface topography in the evolving microstructure and functionality of tribofilms of an epoxy-based nanocomposite JF - Wear N2 - The topographic effect of steel counterface, finished by mechanical grinding with Ra ranging from 0.01 to 0.95 µm, on the structure and functionality of the tribofilm of a hybrid nanocomposite, i.e. epoxy matrix filled with monodisperse silica nanoparticles, carbon fibers and graphite, was systematically investigated. The nanostructure of the tribofilm was comprehensively characterized by using combined focused ion beam and transmission electron microscope analyses. It was identified that oxidation of the steel surface, release, compaction and tribosintering of silica nanoparticles and deposition of an epoxy-like degradation product as well as fragmentation of carbon fibers are main mechanisms determining the structure and functionality of the tribofilm. The size of roughness grooves determines the type and size class of wear particles to be trapped at the surface. An optimum groove size leading to a maximum of surface coverage with a nanostructured tribofilm formed mainly from released silica nanoparticles was identified. KW - hybrid nanocomposite KW - tribological performance KW - topographic effect KW - tribofilm KW - nanostructure PY - 2016 DO - https://doi.org/10.1016/j.wear.2016.06.012 VL - 364-365 SP - 48 EP - 56 PB - Elsevier B.V. AN - OPUS4-37937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhao, F. A1 - Li, G. A1 - Österle, Werner A1 - Häusler, Ines A1 - Zhang, G. A1 - Wang, T. A1 - Wang, Q. T1 - Tribological investigations of glass fiber reinforced epoxy composites under oil lubrication conditions JF - Tribology International N2 - The tribological performance of short glass fibers (SGF),solid lubricants and silica nanoparticles filled epoxy (EP) composites was investigated under oil lubrication conditions. It is demonstrated that the addition of SGF greatly reduces the friction and wear of EP. However, further addition of solid lubricants and silica nanoparticles does not change obviously the friction and wear. It is identified that the high tribological performance of SGF reinforced EP is related to the high load carrying capacity and abrasion resistance of SGF. The nanostructure of the tribofilm was comprehensively characterized. It is deemed that the tribofilm plays an important role in the tribological performance by avoiding the direct rubbing of the sliding pairs exposed to boundary and mixed lubrication conditions. KW - Reinforced epoxy composites KW - Short glass fiber KW - Oil lubrication KW - Tribofilm PY - 2016 DO - https://doi.org/10.1016/j.triboint.2016.07.002 SN - 0301-679X VL - 103 SP - 208 EP - 217 PB - Elsevier Ltd. AN - OPUS4-38145 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Dmitriev, A.I. A1 - Gradt, Thomas A1 - Häusler, Ines A1 - Hammouri, Basem A1 - Morales Guzman, Pablo Israel A1 - Wetzel, B. A1 - Yigit, D. A1 - Zhang, G. T1 - Exploring the beneficial role of tribofilms formed from an epoxy-based hybrid nanocomposite JF - Tribology International N2 - The composition and nanostructure of a beneficial tribofilm formed during sliding of a hybrid nanocomposite against steel were characterized comprehensively. A similar nanostructure was produced by high energy ball milling of the three identified tribofilm constituents: silica, hematite and graphite. By supplying powders to a pin-on-disc test it has been shown that neither silica, nor hematite, nor a mixture of both provide the low coefficient of friction (COF) observed for the hybrid composite. Only if graphite was blended with the oxides, the low COF was obtained. Thus, a film of finely dispersed stable inorganic wear products containing 15 vol% graphite provides low friction and wear in the considered case. KW - TEM KW - Nanocomposite KW - Tribofilm KW - Ball milling KW - Pin-on-disc test PY - 2015 DO - https://doi.org/10.1016/j.triboint.2015.03.006 SN - 0301-679X VL - 88 SP - 126 EP - 134 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-33035 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wollschläger, Nicole A1 - Österle, Werner A1 - Häusler, Ines A1 - Stewart, M. T1 - Ga+ implantation in a PZT film during focused ion beam micro-machining JF - Physica status solidi C N2 - The objective of the present work was to study the impact of Focused Ion Beam (FIB) machining parameters on the thickness of the damaged layer within a thin film PZT. Therefore, different Ga+- ion doses and ion energies were applied to a standard PZT film (80/20 lead zirconium titanate) under two beam incidence angles (90° and 1°). The thicknesses of the corresponding Ga+-implanted layers were then determined by cross-sectional TEM in combination with energy dispersive spectroscopic (EDS) line-scans and correlated with polarisation hysteresis loops. The results show a decrease of Ga+-implanted layer thickness with decreasing inclination angle, whereas ion energy and ion dose could be correlated with gallium concentration in the implanted layers.. Under the most unfavorable conditions the depth of the affected zone was 26 nm, it was only 2 nm for the most favorable conditions. KW - PZT KW - Focused ion beam KW - Gallium implantation KW - Polarisation-electric field loop PY - 2015 DO - https://doi.org/10.1002/pssc.201400096 SN - 1610-1634 SN - 1862-6351 SN - 1610-1642 VL - 12 IS - 3 SP - 314 EP - 317 PB - Wiley-VCH CY - Berlin AN - OPUS4-32872 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Giovannozzi, A. A1 - Gradt, Thomas A1 - Häusler, Ines A1 - Rossi, A. A1 - Wetzel, B. A1 - Zhang, G. A1 - Dmitriev, A.I. T1 - Exploring the potential of Raman spectroscopy for the identification of silicone oil residue and wear scar characterization for the assessment of tribofilm functionality JF - Tribology International N2 - We applied a combination of Raman spectroscopy (RS) and cross-sectional transmission electron microscopy (X-TEM) to identify silicone oil residues and tribofilms at steel disc surfaces after tribological testing. Neither chemical cleaning nor mechanical removal of a 50 µm thick surface layer produced a surface without any silicone residue. Nevertheless, long-term tribological properties are not affected due to silicone degradation which has been proved by Raman spectroscopy. Excellent anti-wear and anti-friction properties of a nanocomposite at severe stressing conditions correlated with the formation of a silica-based tribofilm containing amorphous and graphite-like carbon nanoparticles. Since reliable carbon quantification by analytical TEM is difficult, RS is a useful complementary method for carbon identification at wear scars. KW - Raman spectroscopy KW - Cross-sectional TEM KW - Silicone oil residue KW - Tribofilm PY - 2015 DO - https://doi.org/10.1016/j.triboint.2015.04.046 SN - 0301-679X VL - 90 SP - 481 EP - 490 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-33421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Häusler, Ines A1 - Moeck, P. A1 - Volz, K. A1 - Neumann, W. T1 - Orientation relationships of Mn0.75Ga0.25As crystallites on and within GaAs determined by scanning nano beam electron diffraction JF - Crystal Research and Technology N2 - Mn0.75Ga0.25As crystallites, partially embedded on and fully embedded within a single crystalline matrix of GaAs formed during metal organic vapor phase epitaxy (MOVPE) of Mn-rich (Mn,Ga)As on (001) oriented GaAs wafers. Phase and orientation analysis of these crystallites were performed with scanning nano beam electron diffraction (SNBED). The investigation of plan-view specimens using a liquid nitrogen cooling stage enabled the phase and orientation analysis of partially embedded ferromagnetic a-phase particles. In all specimens the following two orientation relationships (O) between the a-phase particles and the GaAs matrix were determined: O1: [1-2.0] Mn0.75Ga0.25As || [110] GaAs and [10.2] Mn0.75Ga0.25As || [-110] GaAs O2: [10.2] Mn0.75Ga0.25As || [110] GaAs and [1-2.0] Mn0.75Ga0.25As || [-110] GaAs. The study of cross-sectional specimens enabled the analysis of fully embedded crystallites. It could be unambiguously detected that a fully embedded crystallite has the structure of the atomically ordered monoclinic β' phase. The β' phase crystallite consists of two domains which are related in twin positions to each other. The orientation relations of the different particles are illustrated by color coded stereographic projections. KW - (Mn,Ga)As crystallites KW - Scanning nano beam electron diffraction KW - Crystal phase determination KW - Orientation mapping KW - STEM/TEM imaging PY - 2017 DO - https://doi.org/10.1002/crat.201600261 SN - 1521-4079 SN - 0232-1300 VL - 52 IS - 1, Special Issue: Anniversary Issue: 50 Years of Crystal Research & Technology SP - 138 EP - 145 PB - Wiley AN - OPUS4-38939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Häusler, Ines T1 - Volume fraction determination of discretely oriented disc-shaped precipitates in transmission mode T1 - Bestimmung des Volumenanteils von diskret orientierten kreisscheibenförmigen Ausscheidungen im Transmissionsmodus JF - Practical Metallography N2 - In der vorliegenden Arbeit wurde eine Formel zur Berechnung des Volumenantei ls dis­ kret orientierter scheibenförmiger Phasen für die Untersuchung im Transmissionsmodus hergeleitet, validiert und mit bereits veröffent­ lichen Formeln verglichen. Bei diesem Ver­ gleich konnte gezeigt werden,dass die in zahl­ reichen Veröffentlichungen benutzte Formel von E. E. Underwood für die Volumenanteils­ bestimmungbeidiskret orientierten Ausschei­ dungsphasen nicht benutzt werden sollte, da sie den Volumenanteil deutlich unterschätzt. Die Ursache liegt in der von E.E. Underwood getroffenen Annahme, dass die kreisförmigen Scheiben regellos angeordnet und nicht aus­ gerichtet sind, was in Al-Legierungen in der Regel nicht der Fall ist. KW - Material KW - TEM KW - Volumenbruchteil KW - Al-Cu-Li-Legierung KW - Ausscheidungen PY - 2017 DO - https://doi.org/10.3139/147.110471 SN - 0032-678X SN - 2195-8599 VL - 54 IS - 12 SP - 816 EP - 837 PB - Carl Hanser AN - OPUS4-43722 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dmitriev, A. I. A1 - Häusler, Ines A1 - Wetzel, B. A1 - Zhang, G. A1 - Österle, Werner T1 - Modeling of the stress-strain behavior of an epoxy-based nanocomposite filled with silica nanoparticles JF - Materials and Design N2 - The method of movable cellular automata (MCA) was applied to simulate the stress-strain behavior of a nano composite consisting of an epoxy matrix and 6 vol. % silica nano particles. The size of the elements used for modelling was fixed at 10 nm, corresponding approximately to the diameter of the filler particles. Since not only the stress-strain response of the two constituents but also debonding of neighboring particles and granular flow was taken into account, plastic deformation as well as crack initiation and propagation could be simulated with the model. Modelling results were compared with tensile test results of both, pure epoxy as well as the epoxy-6 vol. % SiO2 composite. Since assuming bulk properties of the two constituents did not yield satisfactory results, slight modifications of the nanoparticle response functions and nanostructures were tested numerically. Finally, it was observed that only the assumption of slightly increased strength properties of the epoxy yielded good correlation between experimental and modelling results. This was attributed to an increased cross linking of the epoxy caused by the presence of silica nano particles. KW - Nanocomposite KW - Polymer matrix composite KW - Stress-strain behavior KW - Modeling KW - Computational mechanics PY - 2016 DO - https://doi.org/http://dx.doi.org/10.1016/j.matdes.2015.10.038 SN - 0264-1275 VL - 89 SP - 950 EP - 956 PB - Elsevier AN - OPUS4-35596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -