Materials Literature
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Bismuth–silica nanocomposites and polycrystalline bismuth were prepared via powder metallurgy in order to study the influence of silica inclusions on the thermoelectric properties of bismuth. Bi–SiO2 powders containing from 0.5 to 15 vol. % of silica and pure Bi powders were produced by an arc-plasma processing. Trans…
The synthesis and characterization of the copper(II) complex [Cu 2 (dpt) 2 {(μ-O 2 C)[(η 5 -C 5 H 4 )Fe(η 5 -C 5 H 5 )]} 2 ](ClO 4 ) 2 ( 1 ), where dpt = dipropylenetriamine, are reported, and its structure was determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group…
Scanning tunneling spectroscopy was performed on small pristine silicon clusters on graphite. For the investigated clusters with sizes between 2.5 and 40 \AA{}, two distinct size regimes, were found: below 15 \AA{}, Si clusters show energy gaps up to 450 meV, above that size only zero gaps are observed. We conclude th…
We present a linear stability analysis for epitaxial growth of strained-layer superlattices, calculating how a shape perturbation propagates through the whole multilayer stack. We assume that bulk diffusion is negligible, so the morphology is controlled by surface diffusion. Unlike the case of a single strained layer,…
We have prepared a sintered CoSb3–FeSb2 composite where the FeSb2 particles are dispersed in the CoSb3 matrix by mechanical grinding (MG) and hot pressing, and investigated the Seebeck coefficient, electrical resistivity, and thermal conductivity in order to estimate the corresponding figure of merit. The thermal cond…
Nd 57 Fe 20 B 8 Co 5 Al 10 bulk cylinders and ribbons were quenched from the melt at different cooling rates using copper mold casting and melt spinning, respectively. Both the melt-spun ribbons and the cast cylinders display x-ray diffraction patterns without obvious crystalline peaks. However, the ribbons show soft…
The \ensuremath{\pi}-electron excitations are studied for a multiwall carbon nanotube, a single-wall carbon nanotube bundle with finite nanotubes, and graphite layers. The loss spectra of the nanotube systems exhibit several plasmon peaks. The most prominent one is the \ensuremath{\pi} plasmon, and the others are the…
The control of the B-site order of Pb(Mg1/3Nb2/3)O3 was studied by the partial substitution at the A site by both donor La3+/Bi3+ and acceptor K+1. Different A-site cations and their concentrations were chosen to modify the chemical order at the B site. The Raman scattering results over a wide temperature range (−190–…
The crystal structure of ZnO is wurtzite and the stacking sequence of atomic layers along the “c” axis is not symmetric. As a result, a ZnO crystal surface that is normal to the c axis exposes one of two distinct polar faces, with (0001̄) being considered the O face and (0001) the Zn face. Photoluminescence (PL) measu…
Wide angle x-ray scattering and classical molecular-dynamics simulations were employed to study structural and dynamic properties of two low-molecular weight glass-forming liquids, propylene carbonate, and salol. We observe pronounced changes in the liquid structure as a function of temperature in a wide temperature r…
The field emission properties of diamond-graphite composites were investigated as a function of composition both for oxidized and hydrogen covered diamond. The composites consist of mixtures of nanocrystalline diamond and graphite particles. In this way their composition could be varied at will while the field enhance…
Cyclooligomeric phthalocyanines with the special feature of having a dehydroannulene core are described. Compounds 4a,b and 5a,b were prepared by an oxidative coupling mediated by copper from the corresponding diethynyl unsymmetrically substituted phthalocyanines 8a,b, which are easily accessible from the correspondin…
Photoluminescence (PL) spectra of as-made porous Si samples were obtained in a wide peak-wavelength range. After exposure to air or coupling with ${\mathrm{C}}_{60}$ molecules, the PL peak shifts to a pinning wavelength within the range of 610--630 nm. This pinning wavelength is almost independent of the size of the o…
Electron transport through nanotubes is studied theoretically using the Landauer formalism. The studies are carried out for finite metallic nanotubes that bridge two contacts pads. The current is observed to increase stepwise with the applied voltage. Each step corresponds to resonance tunneling including one single-p…
On the basis of density-functional theory, we study electronic structures of thin carbon nanotube bundles. We find that nearly-free-electron (NFE) states, which are distributed in intra- and intertube regions, are present at $3\ensuremath{\sim}4\mathrm{eV}$ above the Fermi level. In the intertube region the NFE state…
Raman scattering spectra of polycrystalline ${\mathrm{Sr}}_{8}{\mathrm{Ga}}_{16}{\mathrm{Ge}}_{30},$ ${\mathrm{Eu}}_{8}{\mathrm{Ga}}_{16}{\mathrm{Ge}}_{30},$ ${\mathrm{Cs}}_{8}{\mathrm{Ga}}_{8}{\mathrm{Sn}}_{38},$ and ${\mathrm{Cs}}_{8}{\mathrm{Zn}}_{4}{\mathrm{Sn}}_{37}{\mathrm{Ge}}_{5},$ all with the type-I clathrat…
Abstract. – The change of the structure of concentrated colloidal suspensions upon addition of non–adsorbing polymer is studied within a two–component, Ornstein–Zernicke based liquid state approach. The polymers ’ conformational degrees of freedom are considered and excluded volume is enforced at the segment level. Th…
We have investigated the electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ [at room temperature (RT) and 100 K] and TSeF-TCNQ (RT), which have isomorphic crystal structure, by an ab initio plane-wave pseudopotential band calculation. To express the exchange and correlation energy for electro…
Electrochromic tungsten oxide film was fabricated by a new soft chemistry route, in which the transparent conducting glass substrate was successively dip-coated with poly(acrylic acid) (PAA) and ammonium tungstate solutions. The as-coated composite layer of PAA/(NH 4 ) 2 WO 4 · n H 2 O was dried at a low temperature (…
The core-level x-ray photoemission spectroscopy (XPS) satellites of single-crystalline ${\mathrm{SrTiO}}_{3},$ ${\mathrm{SrTiO}}_{3}:\mathrm{La},$ and ${\mathrm{SrTiO}}_{3}:\mathrm{Nb}$ in situ fractured in ultrahigh vacuum were compared with the electron-energy-loss spectrum and theoretical electron-energy-loss funct…