Materials Literature
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We report improvements in the crystallinity of a III–V-based diluted magnetic semiconductor (Ga, Mn)As by heat treatment (annealing) after growth at comparatively low temperatures. This method can be used to raise the Curie temperature to 100 K without the need for severe optimization of growth conditions, as well as…
The diffusive coarsening of 2D soap froths is governed by von Neumann's law. A statistical version of this law for dry 3D foams has long been conjectured. A new derivation, based on a theorem by Minkowski, yields an explicit analytical von Neumann's law in 3D which is in very good agreement with detailed simulations a…
We have studied the electronic structure of the skutterudite compounds Co(Sb$_{1-x}$Te$_{x}$)$_3$ (x= 0, 0.02, 0.04) by photoemission spectroscopy. Valence-band spectra revealed that Sb 5p states are dominant near the Fermi level and are hybridized with Co 3d states just below it. The spectra of {\it p}-type CoSb$_3$…
Low-temperature (1.8 K) excitonic absorption, reflection and photoluminescence spectra of mixed $Zn(P_{1 - x}As_{x})_{2}$ crystals were studied at $x = $0.01, 0.02, 0.03 and 0.05. Energy gap and rydbergs of excitonic B, C and A-series decrease monotonically at the increase of $x$. Spectral half-widths of absorption $n…
Sintered powders and wires of superconducting $MgB_2$ have been fabricated under a variety of conditions in order to determine details of the diffusion of the $Mg$ into $B$ and to study the types of defects that arise during growth. For samples prepared by exposure of boron to $Mg$ vapor at $950^{\circ}C$, the convers…
We investigate electronic structures of Al quantum wires, both unsupported and supported on the (100) NaCl surface, using the density-functional theory. We confirm that unsupported nanowires, constrained to be linear, show magnetization when elongated beyond the equilibrium length. Allowing ions to relax, the wires de…
Localized interface states in abrupt semiconductor heterojunctions are studied within a tight-binding model. The intention is to provide a microscopic foundation for the results of similar studies which were based upon the two-band model within the envelope function approximation. In a two-dimensional description, the…
The first global simulation of semiconductor-based quantum-cascade lasers is presented; Our fully three-dimensional approach allows to study in a purely microscopic way -without resorting to phenomenological parameters- the current-voltage characteristics of state-of-the-art unipolar nanostructures. Based on the propo…
Transparent lyotropic ferronematic dispersions are synthesized by admixing a cationic ferrofluid to the lyotropic liquid crystal PL/1D/Wt. The transparency is spontaneous and time-independent. It is observed in zero magnetic field in white and polarized light for disordered layers of ferroliquid crystals of thicknesse…
The properties of neutral and anionic ${\mathrm{Pd}}_{N}$ clusters were investigated with spin-density-functional calculations. The ground-state structures are three dimensional for $N>3$ and they are magnetic with a spin triplet for $2\ensuremath{\le}N\ensuremath{\le}7$ and a spin nonet for $N\phantom{\rule{0ex}{0…
The work function at the tips of individual multiwalled carbon nanotubes has been measured by an in situ transmission electron microscopy technique. The tip work function shows no significant dependence on the diameter of the nanotubes in the range of 14–55 nm. Majority of the nanotubes have a work function of 4.6–4.8…
A low energy Ar + ion-beam was used to modify the surface of a high-density polyethylene (HDPE) dry powder. The modification reaction was promoted by the oxygen gas injected during the irradiation. This simple modification route is characterized as a heterogeneous, solvent-free, environmentally favorable process. The…
The coordination chemistry of a Rh(III) porphyrin building block was investigated with a view to the construction of heterometallic arrays of porphyrins. The Rh(III) porphyrin was found to coordinate methanol in the solid state and weakly in CDCl(3) solution. Crystallization afforded five coordinate pi stacked Rh(III)…
The morphological behavior of a series of binary mixtures of polystyrene- block -polyisoprene (SI) diblock copolymers has been investigated by small-angle X-ray scattering and transmission electron microscopy. These mixtures consist of a given asymmetric SI diblock, coded as, which itself exhibits a morphology of poly…
Thermoplastic sheets prepared from soy protein isolate (SPI) with ethylene glycol (EG) as the plasticizer were obtained by compression molding under a pressure of 15 MPa at 150 °C. The effects of the glycol content on the structure and properties of thermoplastic SPI were investigated by using infrared, X-ray diffract…
The change in hardness and chemical potential along a reaction coordinate has been studied on the basis of the finite difference formula for hardness and chemical potential. The conditions where the hardness profile can have an extremum along the reaction coordinate are identified. Numerical demonstrations of inversio…
The kinetics, molecular weight averages, and the average degree of branching, DB, are calculated for the self-condensing vinyl copolymerization (SCVCP) of a vinyl monomer M with an “inimer” AB* in the case of different reactivities of active species. Emphasis is given to two limiting cases: formation of “macroinimers”…
The synthesis of planar arrays of metal nanoparticles is an important goal in nanotechnology. As shown in the picture, superlattices of gold nanoparticles are readily assembled by biomolecular templating using bacterial S-layer membranes. Only nanoparticles of certain size and charge are organized in regular patterns,…
Silberdoppelsalze mit eingeschlossenen Carbidionen wurden mit [15]Krone-5 (15C5) als Strukturdirektor hergestellt. Die Dimensionalität der Verbindungen ist ausgesprochen niedrig; es handelt sich entweder um diskrete Moleküle oder Zickzack-Ketten. Sie enthalten verschiedenartige Silberkäfige, die sandwichartig durch η5…
The order-disorder phase transitions of ${\mathrm{KNO}}_{2},$ ${\mathrm{CsNO}}_{2},$ and ${\mathrm{TlNO}}_{2}$ have been studied using parameter-free molecular dynamics simulation. It is found that the phase transitions in nitrites investigated are driven by the rotations of the ${\mathrm{NO}}_{2}^{\ensuremath{-}}$ io…