Materials Literature
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Molecular dynamics simulations have been used to study the driving force of ion irradiation induced interfacial mixing in metal bilayers in which the relative mass of the constituents is considerable. We find no apparent effect of chemical forces, such as heat of mixing or cohesive energy up to 8 keV ion energy, altho…
Effects of temperature changes on the nonequilibrium spin-glass dynamics of a strongly interacting ferromagnetic nanoparticle system (superspin glass) are studied. In contrary to atomic spin glasses, strong cooling rate effects are observed, and no evidence for temperature-chaos is found. The flip time of a magnetic m…
We present a combined experimental and theoretical study of submonolayer heteroepitaxial growth of Ag on Si(111)-7x7 at temperatures from 420 K to 550 K when Ag atoms can easily diffuse on the surface and the reconstruction 7x7 remains stable. STM measurements for coverages from 0.05 ML to 0.6 ML show that there is an…
A growth model and parameters obtained in our previous experimental (scanning tunneling microscopy, KMC) and theoretical (kinetic Monte Carlo simulations, KMC) studies of Ag/Si(111)-(7x7) heteroepitaxy were used to optimise growth conditions (temperature and deposition rate) for the most ordered self-organized growth…
We report on a significant failure of LDA and GGA to reproduce the phase stability and thermodynamics of mixed-valence Li$_x$FePO$_4$ compounds. Experimentally, Li$_x$FePO$_4$ compositions ($0 \leq x \leq 1$) are known to be unstable and phase separate into Li FePO$_4$ and FePO$_4$. However, first-principles calculati…
Time resolved measurements of magnetization in n-GaAs have revealed a rich array of spin decoherence processes, and have shown that fairly long lifetimes (\sim 100 ns) can be achieved under certain circumstances. In time-resolved Faraday rotation and time-resolved Kerr rotation the evolution of the magnetization can b…
We demonstrate an element-specific measurement of magnetization precession in a metallic ferromagnetic alloy, separating Ni and Fe moment motion in Ni81Fe19. Pump-probe X-ray magnetic circular dichroism (XMCD), synchronized with short magnetic field pulses, is used to measure free magnetization oscillations up to 2.6…
We calculate the cohesive energies of Fe-based glass-forming alloys in the B-Fe-Y-Zr quaternary system. Our {\it ab-initio} calculations fully relax atomic positions and lattice parameters yielding enthalpies of mixing at T=0K. We examine both the known equilibrium and metastable phases as well as a selection of plaus…
We present a methodology for computing the current-voltage response of a molecular wire within the Landauer-Buttiker formalism based upon transforming the cummulative transmission probability into an eigenvalue problem. The method is extremely simple to apply since does not involve construction of the molecular Greens…
Single crystals of Zn_(1-x)Mn_xIn_2Se_4 were grown by the chemical vapour phase transport technique (CVT). The Mn concentration was varied from x=1 to x=0.01. Through X-rays powder diffraction patterns and Laue diagrams of single crystals we studied the transformation from the hexagonal structure of MnIn_2Se_4 to the…
Very rough surfaces can suspend small liquid drops and produce very large contact angles. This behavior often is referred to as ultralyophobicity or super repellency. It is proposed that two criteria must be met to invoke ultralyophobicity: a contact line density criterion and asperity height criterion. The proposed c…
The interactions between various functionalized carbon nanotubes and several types of human cancer cells are explored. We have prepared modified nanotubes and have shown that these can be derivatized in a way that enables attachment of small molecules and of proteins, the latter through a novel noncovalent association…
The alteration in water of homogeneous sodium borosilicate glasses containing different concentrations of zirconium has been studied. The dissolution kinetics were followed by chemical analysis, and the morphology of the interfacial altered layer was studied by small-angle X-ray scattering (SAXS). Two types of dissolu…
Abstract In this article the synthesis and characterization of an elastomeric conducting material, obtained by grafting polyaniline (EB) on commercial cis ‐1,4‐polybutadiene (PB), are described. PB was first partially epoxidized in chloroform solution using meta‐chloroperbenzoic acid (MCPBA). The conducting polymer wa…
Ein alternativer Ansatz zur Synthese von nanostrukturierten Kohlenstoffmaterialien (NCs) beruht auf der Verwendung von kovalent stabilisierten micellaren Vorstufen in wässriger Lösung (siehe Schema). Diese Vorstufen gehören zu einer Klasse schalenvernetzter Nanopartikel (SCKs), die durch Selbstorganisation und Stabili…
We report the results of stochastic molecular dynamics simulations for the structural formation of charged dendrimers and dendrimer-based star polymers. The variation in the radius of gyration explains quite well recent small-angle neutron-scattering experiments for higher-generation charged dendrimers under different…
Reduced-temperature synthesis of single-wall carbon nanotubes (SWNTs) is of interest for their growth into device architectures and their efficient bulk production. SWNTs were grown via the thermal chemical vapor deposition (CVD) of low-pressure ethylene over iron particles supported on silicon wafers at temperatures…
A simultaneous experimental and computational search for polymorphs of chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile) has been conducted, leading to the first characterization of forms 2 and 3. The crystal structure prediction study, using a specifically developed anisotropic atom-atom potential for ch…
Konsekutive Bedampfungszyklen zur Herstellung heterogener Katalysatoren: Aktive Cu- und ZnO-haltige Methanolsynthesekatalysatoren wurden durch die Bedampfung mesoporöser Silicate mit metallorganischen Vorstufen und thermische Nachbehandlung erhalten (siehe Schema). Im Zielmaterial liegen die aktiven Komponenten in nan…
Aromatische Nanokanäle umschließen lineare Gastmoleküle mit konjugierten π-Systemen. Die supramolekularen Architekturen sind durch schwache Wechselwirkungen stabilisiert und schmelzen daher erst bei deutlich höheren Temperaturen als ihre Komponenten. Kurze Kontakte von 2.5 Å zwischen Wasserstoffatomen der Gastmoleküle…