16 research outputs found
Structural reorientation and compaction of porous MoS2 coatings during wear testing
Industrial upscaling frequently results in a different coating microstructure
than the laboratory prototypes presented in the literature. Here, we
investigate the wear behavior of physical vapor deposited (PVD) MoS2 coatings:
A dense, nanocrystalline MoS2 coating, and a porous, prismatic-textured MoS2
coating. Transmission electron microscopy (TEM) investigations before and after
wear testing evidence a crystallographic reorientation towards a basal texture
in both samples. A basal texture is usually desirable due to its low-friction
properties. This favorable reorientation is associated to a tribological
compaction of the porous specimens. Following running-in, sliding under high
contact pressure ultimately leads to a wear rate as small as for an ideal
chemical vapor deposited (CVD) grown bulk MoS2 single crystal reference. This
suggests that the imperfections of industrial grade MoS2 coatings can be
remediated by a suitable pretreatment
Butterfly gyroid nanostructures as a time-frozen glimpse of intracellular membrane development
The formation of the biophotonic gyroid material in butterflywing scales is an exceptional feat of evolutionary engineering of functional nanostructures. It is hypothesized that this nanostructure forms by chitin polymerization inside a convolutedmembrane of corresponding shape in the endoplasmic reticulum. However, this dynamic formation process, including whether membrane folding and chitin expression are simultaneous or sequential processes, cannot yet be elucidated by in vivo imaging. We report an unusual hierarchical ultrastructure in the butterfly Thecla opisena that, as a solid material, allows high-resolution three-dimensional microscopy. Rather than the conventional polycrystalline spacefilling arrangement, a gyroid occurs in isolated facetted crystallites with a pronounced size gradient.When interpreted as a sequence of time-frozen snapshots of the morphogenesis, this arrangement provides insight into the formation mechanisms of the nanoporous gyroid material as well as of the intracellular organelle membrane that acts as the template
Using openBIS as virtual research environment: An ELN-LIMS open-source database tool as a framework within the CRC 1411 Design of Particulate Products
Using openBIS as virtual research environment: An ELN-LIMS open-source database tool as a framework within the CRC 1411 Design of Particulate Products
The digital transformation and, thus, the use of new digital technologies not only has a substantial impact on society and companies but also on science. Analog documentation as we have known it for centuries will eventually be replaced by intelligent and FAIR (Findable, Accessible, Interoperable, and Reusable) systems. In addition to the actual research data and results, metadata now plays an important role, not only in the use of individual, independently existing projects, but also for future use by other scientists and in interdisciplinary research groups and disciplines. The solution presented here of an electronic laboratory notebook and laboratory information management system (ELN-LIMS) based on the openBIS (open Biology Information System) environment offers interesting features and advantages, especially for interdisciplinary work. The Collaborative Research Centre (CRC) 1411 âDesign of Particulate Productsâ of the German Research Foundation is characterized by the cooperation of different working groups of synthesis, characterization, and simulation, and therefore serves as a model environment to present the implementation of openBIS. OpenBIS, as an open source ELN-LIMS solution following FAIR principles, provides a common set of general entries with the possibility of sharing and linking (meta-)data to improve the scientific exchange between all users
Correlative Laboratory NanoâCT and 360° Electron Tomography of Macropore Structures in Hierarchical Zeolites
Hierarchical pore structures exhibit morphological features on several length scales, which govern important materials properties in catalysis, such as catalytic activity, diffusivity or selectivity. Correlative tomography offers unique opportunities for a comprehensive and scaleâbridging 3D characterization of such complex pore morphologies, which is crucial to further optimize materials design and synthesis routines. This study explores the capabilities of correlative 360° electron tomography (ET) and labâbased nano Xâray computed tomography (NanoâCT) enabling 3D analyses of volumes of up to (60 ”m)Âł with down to nm resolution, as demonstrated for zeolite particles with embedded macropores. By first applying the two techniques to the same particle the higher resolution and fidelity of ET are used to improve the segmentation of pore space in the NanoâCT reconstruction. Extended statistical relevance and access to interparticle pore space are obtained from reconstructions of larger particle agglomerates, using the largeâfieldâofâview mode of the NanoâCT. The presented correlative approach enables real space analyses of important pore characteristics for comparison with complementary pore characterization techniques. Moreover, by investigating samples from different stages of the synthesis, 360°âET and NanoâCT provide unique insights into the formation mechanism of porous materials, as demonstrated for the steamâassisted crystallization of the macroporous zeolite particles
Unraveling Structural Details in Ga-Pd SCALMS Systems Using Correlative Nano-CT, 360° Electron Tomography and Analytical TEM
We present a comprehensive structural and analytical characterization of the highly promising supported catalytically active liquid metal solutions (SCALMS) system. This novel catalyst shows excellent performance for alkane dehydrogenation, especially in terms of resistance to coking. SCALMS consists of a porous support containing catalytically active low-melting alloy particles (e.g., Ga-Pd) featuring a complex structure, which are liquid at reaction temperature. High-resolution 3D characterization at various length scales is required to reveal the complex pore morphology and catalytically active sitesâ location. Nano X-ray computed tomography (nano-CT) in combination with electron tomography (ET) enables nondestructive and scale-bridging 3D materials research. We developed and applied a correlative approach using nano-CT, 360°-ET and analytical transmission electron microscopy (TEM) to decipher the morphology, distribution and chemical composition of the Ga-Pd droplets of the SCALMS system over several length scales. Utilizing ET-based segmentations of nano-CT reconstructions, we are able to reliably reveal the homogenous porous support network with embedded Ga-Pd droplets featuring a nonhomogenous elemental distribution of Ga and Pd. In contrast, large Ga-Pd droplets with a high Ga/Pd ratio are located on the surface of SCALMS primary particles, whereas the droplet size and the Ga/Pd ratio decreases while advancing into the porous volume. Our studies reveal new findings about the complex structure of SCALMS which are required to understand its superior catalytic performance. Furthermore, advancements in lab-based nano-CT imaging are presented by extending the field of view (FOV) of a single experiment via a multiple region-of-interest (ROI) stitching approach
Structural reorientation and compaction of porous MoSâ coatings during wear testing
This research was funded by the German Research Foundation (DFG) Priority Program SPP 2074 âFluid-free lubrication systems with high mechanical loadsâ, grant number (GEPRIS) 407707942 (ME 4368/7-1, ME 2670/8-1 and TR 1043/7-1)