Technische Universität Darmstadt

About: Technische Universität Darmstadt is a education organization based out in Darmstadt, Germany. It is known for research contribution in the topics: Neutron & Finite element method. The organization has 17316 authors who have published 40619 publications receiving 937916 citations. The organization is also known as: Darmstadt University of Technology & University of Darmstadt.

Water-Mediated Ion Pairing: Occurrence and Relevance

Abstract: We present an overview of the studies of ion pairing in aqueous media of the past decade. In these studies, interactions between ions, and between ions and water, are investigated with relatively novel approaches, including dielectric relaxation spectroscopy, far-infrared (terahertz) absorption spectroscopy, femtosecond mid-infrared spectroscopy, and X-ray spectroscopy and scattering, as well as molecular dynamics simulation methods. With these methods, it is found that ion pairing is not a rare phenomenon only occurring for very particular, strongly interacting cations and anions. Instead, for many salt solutions and their interfaces, the measured and calculated structure and dynamics reveal the presence of a distinct concentration of contact ion pairs (CIPs), solvent shared ion pairs (SIPs), and solvent-separated ion pairs (2SIPs). We discuss the importance of specific ion-pairing interactions between cations like Li+ and Na+ and anionic carboxylate and phosphate groups for the structure and functioning...

Understanding Structural Changes in NMC Li-Ion Cells by In Situ Neutron Diffraction

Abstract: Commercial NMC cells of 18650-type based on a Lix(Ni0.5Mn0.3Co0.2)O2 cathode and a graphitic anode were studied in situ using a combination of high-resolution monochromatic neutron powder diffraction and electrochemical analysis. The structural changes of the electrode materials during cell charge/discharge have been determined using Rietveld refinement and single profile decomposition techniques. A transformation of the graphitic anode to LiC12 and LiC6 through the formation of higher ordered lithium intercalated carbons was observed. A different behavior of electrochemically-driven lattice distortion was observed for NMC material in comparison to LixCoO2 and its influence on the overall cell performance has been discussed in brief. Detailed analysis of the structural changes in the Lix(Ni0.5Mn0.3Co0.2)O2 cathode material revealed reversible Li/Ni cation mixing (5.6(8)%), which is state-of-charge independent below 1600 mAh and vanishing above 1800 mAh (∼0.8Qmax).

Sr2CrOsO6 : End point of a spin-polarized metal-insulator transition by 5d band filling

Abstract: In the search for new spintronic materials with high spin polarization at room temperature, we have synthesized an osmium-based double perovskite with a Curie temperature of 725 K. Our combined exp ...

On the Modelling and Stabilization of Flows in Networks of Open Canals

Abstract: In this paper, we present a model for the controlled flow of a fluid through a network of canals using a coupled system of St. Venant equations. We then generalize in a variety of ways recent results of Coron, d'Andrea-Novel, and Bastin concerning the stabilizability around equilibrium of the flow through a single channel. This work is based on the theory of quasilinear hyperbolic systems and, in particular, on a delicate result of Li Ta-tsien concerning the existence and decay of global classical solutions.