Materials Literature
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Neue Gerüstmaterialien, die aus wohldefinierten Vanadiumoxidclustern bestehen, wurden durch Niedertemperatursynthesen hergestellt und röntgenographisch charakterisiert. In den Strukturen dieser Feststoffe sind {V18O42}-Käfige vorhanden, die über {M(H2O)4}-Brücken (M = FeII, CoII) zu zwei sich gegenseitig durchdringend…
The thermal stability of nonstoichiometric carbon nitride films has been studied by x-ray absorption near edge spectroscopy. Amorphous carbon nitride thin films were annealed in vacuum up to 1150 °C revealing the presence of nitrogen in different bonding configurations. Annealing to 450 °C results in the loss of ∼50%…
By the synthesis of new titanosilsesquioxanes, which incorporate both alkoxides and BINOL, significant correlations have been found between the nature of the ligands bound to the TiIV centers and the ablility of the complexes to act as catalysts active in the epoxidation of alkenes (see diagram).
An unprecedented nonplanar structure characterizes the complex [Fe(OCH3)2(dbm)]12 (on the left in the picture), which contains the largest cyclic ferric cluster yet reported with chemically equivalent bridging units. It is made up of twelve high-spin, antiferromagnetically coupled iron(III) centers and neatly reacts w…
Titanium alloys are commonly heat-treated to meet specific design requirements. In an effort to possibly create a better composite, the influence of heat treatments on the damage evolution and strength of a SiC/Ti-15-3 metal matrix composite (MMC) was studied. Heat treatments of 450°C and 700°C for 24 hours were perfo…
Local antiferroelectric order of lattice distortion caused by an ionic size difference has been discovered in relaxor lead scandium niobate, $\mathrm{Pb}(\mathrm{Sc}{}_{1/2}\mathrm{Nb}{}_{1/2})\mathrm{O}{}_{3}$, using an x-ray diffuse scattering technique. This ordering nature is thought to produce a glassy motion of…
More than 10 000 carboxylic acid groups are covalently coated on monodisperse silica nanoparticles (see schematic diagram) prepared by a Stöber synthesis. Colloidal super crystals form spontaneously on dissociation in aqueous dispersion with low ionic strength.
Secondary hydrogen-bonding interactions have been exploited to construct layered magnetic solids based on amidinium–carboxylate salt bridges. The salt bridge is utilized as a supramolecular synthon to set the structural organization in a layered motif; it also serves as a spin communication element. The magnetic mater…
In this work, we add a small amount of a guest–host dye G-206 in the polymer-dispersed liquid crystal mixtures to fabricate holographic gratings. Following formation, the grating is irradiated by a single Ar+ laser beam while probed by a He–Ne laser. Experimental results indicate that the first-order diffracted intens…
We report a technique which allows self-assembly of conducting nanoparticles into long continuous chains. Transport properties of such chains have been studied at low temperatures. At low bias voltages, the charges are pinned and the chain resistance is exponentially high. Above a certain threshold VT, the system ente…
A novel type of electron-rich (basic!) nanosized channels can be built up by linking giant ring-shaped building blocks, which occur in the layered compound of composition [Mo124VIMo28VO429(μ3-O)28H14(H2O)66.5]16− (see figure). The corresponding sodium salt is obtained by reduction of an acidified aqueous molybdate sol…
Direct reaction of ytterbium or europium metal with 2,6-diphenylphenol yields novel lanthanoid aryloxides, including a unique diytterbium(II) cation with aryloxides solely as bridging ligands (figure).
The anisotropic magnetic susceptibilities of single crystals of the isostructural layered antiferromagnets, MnPS 3 ( T N = 78 K) and MnPSe 3 ( T N = 74 K), have been measured as functions of temperature. In both compounds, divalent manganese is present in the high-spin S = 5/2 state. The anisotropies in the susceptibi…
We report on the direct observation of stretched exponential relaxation in low-temperature monatomic Lennard-Jones systems which were cooled slowly from the liquid phase to form crystals with a large number of defects. We use the cage correlation function [E. Rabani, J. D. Gezelter, and B. J. Berne, J. Chem. Phys. 107…
An experimental atomic resolution analysis of an undoped Σ5 36° [001] tilt grain boundary in SrTiO3 shows that the structure contains incomplete oxygen octahedra. These incomplete octahedra act as effective oxygen vacancies and lead to a fixed, positive boundary charge. Annealing the boundary in the presence of MnO2 d…
Mixed-metal mesocates [M2Pd3Br6L6]4− (M=TiIV, SnIV; L=4-diphenylphosphanyl-catecholate) have been synthesized, in which the two incommensurate symmetry elements generated by the different metal ions are linked by a rigid, bifunctional ligand to generate a C3h-symmetrical cluster (see picture).
We study both the longitudinal and transverse fluctuations of a semiflexible filament. Using scaling arguments and numerical simulations, we find several regimes for the longitudinal fluctuations which, for short times, scale as $〈\ensuremath{\delta}{r}_{\ensuremath{\Vert}}^{2}〉\ensuremath{\sim}{t}^{7/8}$ and are corr…
The fine-tuning of the critical temperature and the coercivity of compounds with two interpenetrating quasi-perpendicular honeycomblike networks (see diagram) are presented. Molecule-based magnets of formula [(Etrad)2M2{Cu(opba)}3]⋅S and mixed compounds of formula [Etrad2Mn2−2xCo2xCu3] were synthesized and their magne…
A molecular composite prepared by the solubilization of pyrene in poly(propyleneimine) dendrimers is investigated by fluorescence and absorption spectroscopy at a range of pH values. The release of pyrene is induced in acidic media, while pyrene incorporation is favored in basic environments, as shown here.
The morphology of surfaces of arbitrary orientation in the presence of step and kink Ehrlich-Schwoebel effects (SESE and KESE) during growth is studied within the framework of a model in which steps are continuous lines, and is illustrated by a simple solid-on-solid model. For vicinal surfaces KESE induces an instabil…