Materials Literature
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The rodlike microcrystal suspension prepared by sulfuric acid hydrolysis of bacterial cellulose was found to undergo spontaneous nematic phase separation after complete desalination. This phase separation was preceded by a birefringent glassy-like state for about 1 week. Addition of trace electrolyte (<1 mM NaCl) caus…
The paper reports the synthesis of the first-row transition metal hexaethylporphodimethene derivatives [(Et6N4)M] [M=Mn, 3; M=Co, 5; M = Cu, 7] on a multigram scale, which makes them easily available for reactivity studies. After synthesis they were converted into the corresponding five-coordinate [(Et6,N4)M(L)] [M =…
The dynamic structure factor of cubic boron nitride has been measured using nonresonant inelastic x-ray scattering. The experimental data are compared with the results of a recently developed ab initio calculation scheme, which takes into account the interaction between the excited electron and the hole. The agreement…
Crystalline SiGe alloy sheet polymers were topotactically prepared from epitaxially grown calcium germanosilicide Ca(Si1−xGex)2 precursor films in the whole composition range. These polygermanosilynes are found to be a well-defined mixture of the known siloxene and polygermyne sheet polymers with the OH groups exclusi…
The interaction of phonon states with the point, line, and plane defects is considered near the edge of an optical-phonon branch. Because the effect of disorder on optical phonons is ordinarily studied in the Raman experiments, we calculate the averaged phonon Green's function characterizing the Raman line shape. Ther…
Mit dem organischen Segment konjugiert ist die Mo≡N-Bindung in den neuartigen molekularen organisch-anorganischen Hybridmaterialien, die durch Pd-katalysierte Kupplung eines iodfunktionalisierten Hexamolybdatanions und eines Alkins erhalten wurden (siehe Schema; Ar=4-Methylphenyl, 3,5-Di(tert-butyl)phenyl). Die Wechse…
The effect of an exchange field on the electrical transport in thin films of metallic ferromagnetic manganites has been investigated. The exchange field was induced both by direct exchange coupling in a ferromagnet/antiferromagnet multilayer and by indirect exchange interaction in a ferromagnet/paramagnet metallic sup…
Representative metal complexes of a biconcave D4-symmetric porphyrin were synthesised by metalion insertion into the porphyrin ligand 1. The NMR spectra suggested D4-symmetry for the ZnII and dioxo-RuVI complexes of 1 and C4-symmetry for the unsymmetrically ligated RuII and RhIII complexes. Metal complexes of 1 proved…
Wetting of the Sigma = 5 (310) <001> symmetrical tilt grain boundary (GB) close to the solubility limit in the Cu(Ag) solid solution has been observed by means of Monte Carlo simulations at T = 600 K. More precisely, a finite thickness film almost pure in Ag, separating the two initial Cu(Ag) grains, can be obtained f…
Mid-infrared pump-probe measurements with subpicosecond time resolution reveal the existence of a metastable condensed phase of the electron-hole ensemble in a direct-gap semiconductor CuCl. High-density electrons and holes are directly created in a low-temperature state by the resonant femtosecond excitation of excit…
The nucleation and growth of carbon nanotubes assisted by microwave plasma on metal surfaces have been observed by transmission electron microscopy. Microwave plasma generated nanoparticles of various sizes on metal surfaces. Initially, the nanoparticles were embedded in an amorphous carbon layer and led to the format…
The dielectric loss in amorphous, thin-film oxide insulators produces a real part of the ac conductivity σ′(ω) that scales as ωs with s∼1. Conventional models explain this frequency dependence by hopping or tunneling of charge between neighboring defect sites. These models fail at low temperatures since they predict t…
Eine stabile Organokupfer(II)-Verbindung mit einem einfach N-invertierten Calix[4]phyrin als C-Ligand wurde synthetisiert und durch eine Röntgenstrukturanalyse charakterisiert (siehe Bild). Für die Bildung der Metall-Kohlenstoff-Bindung erwies sich eine vollständige π-Konjugation als nicht notwendig.
High diffraction efficiencies have been achieved with polarization gratings recorded in thin films of an azobenzene side-chain liquid crystalline polyester by means of biphotonic processes. Efficiency values up to 30% have been reached after an induction period of 300 s and subsequent evolution with the sample in dark…
We use the anomalous x-ray diffraction technique to investigate the nature of the tantalum displacement pattern in the modulated phase of the charge-density-wave compound (TaSe4)2I. In addition to the known acousticlike modulation, we find the first direct evidence for the condensation of opticlike Ta displacements al…
Nanotubes like feather boas were synthesised by the decomposition of methane in a nitrogen atmosphere using a bias-enhanced hot-filament chemical vapour deposition technique. This new type of slightly nitrogenated carbon (C:N) nanotubes exhibits a vermicular shape. Graphitic thin foils growing perpendicular to the tub…
The magnetic properties and microstructural evolution of Zr-doped FePt alloy films prepared by dc-magnetron sputtering were investigated. Compared to an undoped Fe59Pt41 binary film, Zr-doped FePt alloy films showed accelerated ordering transformation kinetics accompanying smaller grains: we were able to fabricate a Z…
Transparent glasses in the system (100–x) Li2B4O7–xSrBi2Ta2O9 (0⩽x⩽20) were fabricated via a splat-quenching technique. The glassy nature of the as-quenched samples was established by differential thermal analyses. X-ray powder diffraction and transmission electron microscopic studies confirmed the amorphous nature of…
The first experimental evidence for triclinic symmetry of bulk smectic liquid-crystal samples of achiral banana-shaped molecules is presented. This phase corresponds to the so-called Sm-CG phase consisting of biaxial molecules and characterized by two tilt directions with respect to the layer normal: tilt of the molec…
We report experimental and theoretical results on the effect of electromagnetic coupling between metal particles in surface-enhanced Raman scattering (SERS). Model calculations of the near-field optical properties of Ag and Au nanoparticle-aggregates show that the electromagnetic surface-enhancement factor can reach 1…