Materials Literature
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We have studied electric-field-induced Raman scattering in SrTiO3 thin films using an indium-tin-oxide/SrTiO3/SrRuO3 structure grown by pulsed laser deposition. The soft mode polarized along the field becomes Raman active. Experimental data for electric-field-induced hardening of the soft modes and the tuning of the s…
We present an extensive electron energy loss spectroscopy study of the low-loss energy region, recorded on multishell carbon and boron-nitride nanotubes and carbon hyperfullerenes. Collections of spectra were recorded in a scanning transmission electron microscope by scanning a subnanometer probe from vacuum into the…
The hexa-tert-butyl substituted hexa-peri-hexabenzocoronene was synthesized in an overall yield of 83% from 4-tert-butylphenylacetylene. The key step was the oxidative cyclodehydrogenation of hexa(4-tert-butylphenyl)benzene with anhydrous FeCl3 in CH2Cl2 The high solubility of hexa-tert-butyl-hexa-peri-hexabenzocorone…
A series of BaTiO3 thin films with various thicknesses from 10 to 400 nm were epitaxially grown under various oxygen pressures from 2×10−4 to 12 Pa on SrTiO3 (001) substrates using laser molecular beam epitaxy. Being confirmed by reflection high energy electron diffraction, atomic force microscopy, x-ray diffraction,…
We investigated the hydrostatic and shear strain components introduced in the graphite hexagons by applying hydrostatic pressure to single-walled carbon nanotubes. The vibrational modes are expected to show different pressure derivatives depending on the polarization of the eigenvector with respect to the nanotube axi…
The structure and electronic properties of 1-ML Au supported on ${\mathrm{TiO}}_{2}(110)$ have been theoretically investigated using the full potential linearized augmented plane-wave method. Based on total-energy and atomic-force calculations, the preferential adsorption site for the Au adatom is predicted to be the…
Specific peaks of the Raman spectrum of single-wall nanotubes shift significantly upon immersion of the tubes in a liquid, relative to the corresponding peaks in air. This observation means that nanotubes are sensitive to molecular forces, and is interpreted by relating the corresponding molecular strain to a thermody…
Extended π-conjugated systems and tunable optic properties are characteristic for compounds with linear backbones based on electron-donating thiophene, electron-accepting pyridine, and a σ3,λ3-phosphole core. The oligomers 1 and 2 are fluorescent chromophores and, for 2, these properties are tunable through chemical m…
This review article covers the research work that has been conducted in solid-electrolyte membrane reactors (SEMR). An overview of the types of solid electrolytes and their applications in heterogeneous catalysis is first presented, followed by a survey of SEMR studies published until 1998. Earlier and recent developm…
Increasingly expanded porphyrinoids (example shown) are provided by new synthetic methods. These nonaromatic systems, which contain up to 16 conjugated pyrrole subunits, exhibit novel metal coordination chemistry, chirality, and anion binding characteristics.
In this letter, we report an experimental study on the influences of 10 at. % Ca2+ and La3+ doping on dielectric properties and dc conductivity of SrBi2Nb2O9 ferroelectric ceramics. All the samples were made by two-step solid-state reaction sintering at temperatures up to 1150 °C for 0.5–1 h in air. X-ray diffraction…
Heterogeneous catalytic epoxidation of functionalized olefins in the liquid phase has been reviewed, focusing on catalyst performance and its interrelation with the crucial parameters of the catalytic systems. Efficient catalysts include supported and mixed oxides, framework-substituted (“redox”) molecular sieves, lay…
The Landau-Zener method allows to measure very small tunnel splittings Δ in molecular clusters Fe 8 . The observed oscillations of Δ as a function of the magnetic field applied along the hard anisotropy axis are explained in terms of topological quantum interference of two tunnel paths of opposite windings. Studies of…
Uniform arrays of Fe nanowires were prepared by electrochemical deposition of iron into nanoporous anodic aluminum oxide films. The microstructure and crystal structures of the nanowires were studied by transmission electron microscopy and electron diffraction. It was found that each nanowire looked like a chain of do…
The thermal conductivity of polycrystalline samples of $(\mathrm{N}\mathrm{a},\mathrm{C}\mathrm{a}){\mathrm{Co}}_{2}{\mathrm{O}}_{4}$ is found to be unusually low, 20 mW/cmK at 280 K. On the assumption of the Wiedemann-Franz law, the lattice thermal conductivity is estimated to be 18 mW/cm K at 280 K, and it does not…
Temperature variation of the crystal structure has been investigated for ${\mathrm{TbBaCo}}_{2}{\mathrm{O}}_{5+\ensuremath{\delta}} (\ensuremath{\delta}=0.5),$ which shows a metal-insulator (MI) transition at ${T}_{\mathrm{MI}}\ensuremath{\approx}340 \mathrm{K}.$ The compound has an oxygen-deficient perovskite structu…
In this letter evidence for the formation of a valence-fluctuation state of iron, formally denoted as Fe2.5+, is presented. The system under study is the Sr2FeMoO6−w double perovskite, known for exhibiting a very large magnetoresistance. Samples of Sr2FeMoO6−w were synthesized by means of an encapsulation technique ut…
A right-handed helical motif is shown by the spiral silica shown in the picture. It is formed by sol–gel polycondensation of tetraethoxysilane in the gel phase supported by an azacrown-appended cholesterol gelator. This is rare example of “chirality” being created in the inorganic material by the template method.
We report atomic resolution Z-contrast scanning transmission electron microscopy images that reveal the incorporation of I atoms in the form of helical chains inside single-walled carbon nanotubes. Density functional calculations and topological considerations provide a consistent interpretation of the experimental da…
Bridging methylene groups are transformed into terminal methyl groups when periodic mesoporous methylenesilicas, prepared for the first time by surfactant-templated synthesis, are subjected to controlled thermal treatment at 350–600°C. The methylene groups integrated “inside the channel walls” transform smoothly to me…