Materials Literature
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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…
A family of crystal structures of carbon composed of alternating ${\mathrm{sp}}^{2}$ and ${\mathrm{sp}}^{3}$ bonds is investigated. Graphitic strips are connected by ${\mathrm{sp}}^{3}$ bonds to form an array of hexagonal pillars exhibiting a honeycomb lattice in the perpendicular plane. The electronic structure and e…
This paper considers the effects of a realistic description of phonons in diamondlike semiconductors and their conversion on the abrupt heterointerfaces on the thermal conductivity of the superlattice (SL). Due to the much larger mass of Ge atoms in comparison to Si, the most probable acoustic phonons in Si layers at…
We study the effective interactions, structure, and the isothermal compressibility of a binary mixture interacting with pairwise additive pair potentials. By integrating out the degrees of freedom of species 2 in the partition sum we first show that a binary mixture can be mapped formally onto an effective one-compone…
The spin configuration of isoelectronic vacancies surrounded by first-row atoms is studied within density-functional theory (DFT) using the local spin density approximation. Allowing for a symmetry break in the electronic system, a mixed-spin state is found to be lowest in energy. It is accompanied by a magnetization…
High-resolution Compton scattering measurements on Be single crystals along three main crystallographic directions ([10\ensuremath{\cdot}0], [11\ensuremath{\cdot}0], and [00\ensuremath{\cdot}1]) have been carried out using incident photon energies of 10, 29, and 56 keV to study the energy dependence of the scattering…
We have calculated the electronic structure of spherical PbS, PbSe, and PbTe quantum dots using a four-band envelope-function formalism that accounts for band anisotropy. By comparing our results with an analytical calculation that assumes a spherical approximation of the $\stackrel{\ensuremath{\rightarrow}}{k}\ensure…