Materials Literature
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Abstract Epoxy foams were prepared from the commercial system (LY 5054 epoxy resin, HY 5054 amine as curing agent, and DY 5054 siloxane as foaming agent) supplied by Ciba‐Geigy. From the differential scanning calorimeter results the optimal epoxy–amine ratio was determined. A maximum T g ∞ value of 85°C was found for…
Der CO-induzierte Abbau von Rh-Clustern auf einer Al2O3-Oberfläche wurde mithilfe der energiedispersiven Röntgenabsorptionsspektroskopie (DXAFS) mit einer Zeitauflösung von 100 ms in Elementarschritten verfolgt (siehe Bild). Diese verbesserte, zeitaufgelöste DXAFS-Technik ermöglicht die detaillierte Untersuchungen der…
The disintegration of Rh clusters on an Al2O3 surface induced by CO, the elementary steps, and timescale of the reaction are analyzed for the first time by energy-dispersive X-ray absorption fine structure (DXAFS) at a time resolution of 100 ms (see picture). This study by the improved time-resolved DXAFS technique pr…
A ferroelectric field effect approach is presented for modulating magnetism in the colossal magnetoresistive oxide ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ (LSMO). The ferromagnetic Curie temperature of ultrathin LSMO films was shifted by 35 K reversibly using the polarization field of the…
The sulfur–nitrogen radical p-O2NC6F4CNSSN. (see packing diagram) provides a rare example of an organic radical that orders ferromagnetically above 1 K. It is suggested that the near orthogonal nature of the singly occupied molecular orbitals of neighboring molecules is important for such behavior to be observed.
Große Einkristalle des chiralen Ferrimagneten [{Cr(CN)6}{Mn(S)-pnH(H2O)}](H2O) entstehen bei der Reaktion von K3[Cr(CN)6], Mn(ClO4)2 und (S)-1,2-Diaminopropan-Dihydrochlorid (siehe Bild; (S)-pn=(S)-1,2-Diaminopropan). Die MnII- und CrIII-Zentren der Verbindung wechselwirken ferrimagnetisch; die Übergangstemperatur bet…
Large single crystals of the chiral ferrimagnet [{Cr(CN)6}{Mn(S)-pnH(H2O)}](H2O) can be recovered from the reaction between K3[Cr(CN)6], Mn(ClO4)2, and (S)-1,2-diaminopropane dihydrochloride (see picture). Magnetic measurements of the complex show that MnII and CrIII ions interact ferrimagnetically, with a magnetic tr…
Electron spins in a semiconductor quantum well couple to an electric field {\it via} spin-orbit interaction. We show that the standard spin-orbit coupling mechanisms can provide extraordinary efficient electron spin manipulation by an in-plane ac electric field.
We report on the fabrication and electrical characterization of field-effect transistors at the surface of tetracene single crystals. We find that the mobility of these transistors reaches the room-temperature value of $0.4 \ cm^2/Vs$. The non-monotonous temperature dependence of the mobility, its weak gate voltage de…
We extend the phase-field approach to model the solidification of faceted materials. Our approach consists of using an approximate gamma plot with rounded cusps that can approach arbitrarily closely the true gamma plot with sharp cusps that correspond to faceted orientations. The phase-field equations are solved in th…
We have studied the phase diagram of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ for $0.5<~x<~0.9$ using neutron powder diffraction and magnetization measurements. At 300 K all samples are paramagnetic and single phase with crystallographic symmetry Pnma. As the temperature is reduced a…
The phonon-dispersion relations and elastic constants for ferromagnetic ${\mathrm{Ni}}_{2}\mathrm{MnGa}$ in the cubic and tetragonally distorted Heusler structures are computed using density-functional and density-functional-perturbation theory within the spin-polarized generalized-gradient approximation. For $0.9<…
The surface stress and the contact potential differences of elastically deformed faces of Al, Cu, Au, Ni, and Ti crystals are calculated within the modified stabilized jellium model using the self-consistent Kohn-Sham method. The obtained values of the surface stress are in agreement with the results of the available…
The quantum size oscillations of the energetic properties and the elongation force of the gold slabs and wires, isolated and in a contact with electrodes, are calculated in a free-electron model. A simple relation between the Fermi energy and the square-potential-well depth is used and tested for low-dimensional syste…
We report on the 29Si nuclear spin decoherence time at room temperature for a pure (99.99999%, 7N) and carrier-less (p-type, doping level of 10^15cm-3) silicon in which 29Si nuclei are naturally abundant (4.7%). Despite the experimental difficulties coming from the extremely long spin-lattice relaxation time T1 (of th…
Accurate ab initio full-potential augmented plane wave (FLAPW) electronic calculations within density functional theory in both local density and generalized gradient approximations have been performed for ${\mathrm{Mn}}_{x}{\mathrm{Ge}}_{1\ensuremath{-}x}$ and ${\mathrm{Mn}}_{x}{\mathrm{Si}}_{1\ensuremath{-}x}$ order…
The evolution of the optical phonon spectra of colloidal core/shell CdSe/ZnS quantum dots with an increase of the shell thickness from 0.5 to 3.4 monolayers has been studied by resonant Raman spectroscopy. The results obtained suggest that the ZnS shell changes its structure from amorphous to partly crystalline as the…
The galvanic replacement reaction between Ag nanoparticles and an aqueous HAuCl 4 solution has recently been demonstrated as a simple and convenient route to metal nanostructures with hollow interiors and highly crystalline walls (see, for example, Sun, Y.; Mayers, B. T.; Xia, Y. Nano Lett. 2002, 2, 481. Sun, Y.; Xia,…
A glowing response: Novel fluoride-selective sensors, utilizing fluoride-induced lactonization to highly fluorescent coumarin derivatives, are reported. The incorporation of this sensory system into a conjugated polymer amplifies the fluorescence response which can be detected visually, see scheme; TIPS=triisopropylsi…
We discuss dissipative particle dynamics as a thermostat to molecular dynamics, and highlight some of its virtues: (i) universal applicability irrespective of the interatomic potential; (ii) correct and unscreened reproduction of hydrodynamic correlations; (iii) stabilization of the numerical integration of the equati…