Scientific Events

Room: Seminar Room 1

Workshop: Status and Future Challenges in Characterisation of Interfaces for Electrochemical Applications

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Unraveling the mysteries of faculty applications (in the US)

Unraveling the mysteries of faculty applications (in the US)
The application process for tenure-track university faculty positions in the US is often opaque and unclear. Job listings can be broad and vague and are sometimes difficult to find; clear guidelines for cover letters, research statements, and CVs are non-existent; interview formats vary drastically between departments, even in the same university or college. But fear not! All of these obstacles are surmountable, with sufficient preparation, of course. This talk will attempt to elucidate many of the aspects of the application process. Topics that will be covered include: a brief overview of the American university structure, job responsibilities of a tenure-track professor, how to find job listings, how to determine which universities and departments to apply to, and tips for applying, interviewing, and negotiating. [more]

Investigation of Nanostructural Materials by means of X-Ray Powder Diffraction

Investigation of Nanostructural Materials by means of X-Ray Powder Diffraction
Nanostructured materials represent a well-established part of nanoscience today due to their tunable electrical, optical, magnetic and catalytic properties, and their potential in nanomedicine. There are some common techniques used for the investigation of nanomaterials, e.g. light scattering (DLS and NTA), scanning and transmission electron microscopy (SEM and TEM), fluorescence and IR spectroscopy and many others. X-ray powder diffraction (PXRD) with different geometrical setups is a complementary non-destructive technique for the determination of crystallographic and size-related properties of nanostructured materials. Here, some examples of PXRD measurements in different applications with the use of Rietveld analysis, including size-specific data obtained from colloid-chemical analysis, transmission and scanning electron microscopy will be presented. Several scientific questions will be addressed, like: - How can crystallite size, residual stress and texture be determined for nanostructured materials? - How is it possible to investigate a thin coating of nanomaterials? - Which advantages does a characterization of samples in temperature chamber offer? It will be shown that the non-destructive X-ray method is well suited to describe not only the crystallographic properties of nanostructural materials, but also their size, shape and inner structure with a possible atomic substitution as well as their “nano”-orientation on the surface. All these scientific answers can be received by the use of different X-ray diffractometers such Bruker D8 Advance and Panalytical Empyrean available at the facility for X-ray Diffraction of the University of Duisburg-Essen. [more]

Doping Induced Properties of Nanocrystalline CVD Diamond Films and Particles

MPIE Colloquium
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Microstructures and Mechanical Behavior of FeNiMnAl(Cr) Alloys

FeNiMnAl alloys show a wide range of microstructures and mechanical properties, but have been little explored. Studies on four different types of microstructures in this alloy system will beoutlined: 1) ultrafine microstructures (5-50 nm), present in Fe30Ni20Mn20Al30,Fe25Ni25Mn20Al30 and Fe35Ni15Mn25Al25,which consist of (Fe, Mn)-rich B2-ordered (ordered b.c.c.) and (Ni, Al)-rich L21-ordered (Heusler) phases, and in Fe30Ni20Mn25Al25,which consist of (Ni, Al)-rich B2 and (Fe, Mn)-rich b.c.c. phases, with the phases aligned along <100>; 2) fine microstructures (50-70 nm), present in Fe30Ni20Mn30Al20, Fe25Ni25Mn30Al20, and Fe28Ni18Mn33Al21, which consist of alternating (Fe,Mn)-rich f.c.c and (Ni, Al)-rich B2-ordered plates with an orientation relationship close to f.c.c.(002)//B2(002); f.c.c.(011)//B2(001); 3) coarser (0.5-1.5µm) lamellar microstructures observed in alloys with a lower aluminum content, such as Fe30Ni20Mn35Al15, that consistof alternating (Fe,Mn)-rich f.c.c and (Ni, Al)-rich B2-ordered phases with a Kurdjumov-Sachs orientation relationship between the phases; and 4) high-entropy Fe40.4Ni11.3Mn34.8Al7.5Cr6alloys. The microstructures and mechanical properties in these alloys have been determined as a function of annealing time, testing temperature and strainrate.  Some of the unusual mechanical behavior that has been observed will be emphasized. This research was supported by the US Department of Energy (DOE), Office of Basic Energy Sciences (grant DE-FG02-07ER46392). [more]

Linking Microstructural Evolution and Tribology in Metallic Contacts

Linking Microstructural Evolution and Tribology in Metallic Contacts
The tribology community presently relies on phenomenological models to describe the various seemingly disjointed steady-state regimes of metal wear. Pure metals such as gold -- frequently used in electrical contacts - exhibit high friction and wear. In contrast, nanocrystalline metals, such as hard gold, often show much lower friction and correspondingly low wear. The engineering community has generally used a phenomenological connection between hardness and friction/wear to explain this macroscale response, and thus to guide designs. We present results of recent simulations and experiments that demonstrate a general framework for connecting materials properties (i.e. microstructural evolution) to tribological response. We present evidence that the competition between grain refinement (from cold working), grain coarsening (from stress-induced grain growth), and wear (delamination and plowing) can be used to describe transient and steady state tribological behavior of metals, alloys and composites. We will explore the seemingly disjointed steady-state friction regimes of metals and alloys, with a goal of elucidating the structure-property relationships, allowing for the engineering of tribological materials and contacts based on the kinetics of grain boundary motion. [more]

High-throughput with Particle Technology

High-throughput screening is a well-established method for scientific experimentation in chemistry and biology. Examples are heterogeneous catalysts, drug developments and nanoparticle toxicology. These methods involve the synthesis of small sample volumes often in form of particles that are quickly tested. These tests are designed to quickly obtain easily accessible data (called descriptors) that are related with a predictor function to the desired properties. The descriptor-predictor-relation is found through mathematical modelling and calibration. One particle based high-throughput concept for the evaluation of potential toxicological hazards will be presented in more detail. Furthermore, a new concept is presented which transfers high-throughput screening to the exploration of new structural metals. The method comprises the synthesis of many small alloy samples in form of particles. These samples obtain a defined microstructure by fast or parallel thermal and mechanical treatments and are subsequently subjected to novel fast descriptor tests while a mathematical algorithm develops the predictor function. The method presented here is a collaborative approach among many researchers and also involves sample routing and automation considerations as well as process modelling. [more]
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