Materials Literature
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The cleaved and (2 x 1) reconstructed (111) surface of p-type Si is investigated by scanning tunneling microscopy (STM). Single B acceptors are identified due to their characteristic voltage-dependent contrast which is explained by a local energetic shift of the electronic density of states caused by the Coulomb poten…
We report on the magnetic resonance of NH_3K_3C_60 powders in the frequency range of 9 to 225 GHz. The observation of an antiferromagnetic resonance below the phase transition at 40 K is evidence for an antiferromagnetically ordered ground state. In the normal state, above 40 K, the temperature dependence of the spin-…
The aim of this work is to investigate the performance of internal reforming solid oxide fuel cell (IRSOFC) and gas turbine (GT) combined cycles. To study complex systems involving IRSOFC a mathematical model has been developed that simulates the fuel cell steady-state operation. The model, tested with data available…
Dynamic light scattering data from highly absorbing solutions exhibit intensity−intensity correlation functions characterized by a sum of exponential decays superposed with an oscillatory term. A new analytical treatment is proposed, which explains this behavior as arising from the heterodyning of scattered light from…
We report the bulk polymerization of ethylglycolide (3,6-diethyl-1,4-dioxane-2,5-dione), isobutylglycolide (3,6-diisobutyl-1,4-dioxane-2,5-dione), and hexylglycolide (3,6-dihexyl-1,4-dioxane-2,5-dione) to high molecular weight polymers. The glycolides were prepared by two routes: the reaction of 2-bromoacyl bromides a…
Ein neuer Rekord ist die Gleichgewichtskonstante Kc von 1019, die für die Komproportionierung des Dieisen(II,III)-Komplexes 1 in Acetonitril bestimmt wurde. In Wasser ist der Kc-Wert von 1 viel geringer (107.9), jedoch immer noch höher als der des Creutz-Taube-Ions. Intervalence-Charge-Transfer-Banden treten bei 2520…
A GaN-based metal–insulator–semiconductor (MIS) structure has been fabricated by using ferroelectric Pb(Zr0.53Ti0.47)O3 instead of conventional oxides as insulator gate. Because of the polarization field provided by ferroelectric and the high dielectric constant of ferroelectric insulator, the capacitance–voltage char…
Nanoscale field-effect transistor (FET) has been fabricated from single-walled carbon nanotubes (CNTs). At ∼5 K, the transistor shows pronounced field effect. Most interestingly, reproducible spikes are observed in the channel conductance as a function of the gate voltage. These conductance spikes are attributed to va…
Photostimulated luminescence at room temperature was observed in a fluorozirconate glass which was doped with 1% Eu2+ or 1% Ce3+ and 5% Br− ions. Small crystals of BaBr2 (high-pressure phase) form in the glass on cooling. The Eu2+ and Ce3+ luminescence spectra comprised two emission lines each: for Eu2+ one line at 41…
We observe current rectification in a molecular diode consisting of a semiconducting single-wall carbon nanotube and an impurity. One-half of the nanotube has no impurity, and it has a current-voltage $(I\ensuremath{-}V)$ characteristic of a typical semiconducting nanotube. The other half of the nanotube has the impur…
Many liquid crystal compounds are known to give structures periodic in only one direction, say z , with a period p comparable with the light wavelength . Their optical properties are fully defined by a dielectric tensor field ( z ), which for most crystals is well known. For p < , the periodic structures behave optica…
Local environment surrounding Y atoms in Y2O3:Tb nanocrystals under various heat treatment conditions has been investigated by using the extended x-ray absorption fine structure (EXAFS) technique. X-ray excited luminescence (XEL) with the incident x-ray energy near Y K edge and Tb L edges has also been measured to inv…
Theoretical electronic structure studies of the ground state geometries, binding energies, and magnetic coupling of ${\mathrm{Cr}}_{2}{\mathrm{O}}_{n}$ $(n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1--6)$ clusters have been carried out within a density functional scheme. It is shown that the magnetic coupling…
We observed violet/blue light emitted from cerium silicates which may be useful for silicon-based optoelectronics. The cerium silicate was produced during a rapid thermal annealing at high temperature (&gt;1100 °C) from the interface between silicon substrate and cerium oxide film. Detailed experiments including x…
Organic, nanoporous heterogeneous catalysts based on a carboxylate-containing, amphiphilic mesogen catalyze the Knoevenagel condensation (see schematic representation). These networks maintain their order in solution and can be recycled. Enhanced basicity, excellent site accessibility, and substrate size exclusion are…
By tailoring capillary interactions at a fluid-fluid interface, a hierarchical two-dimensional self-assembly of hexagonal millimeter-sized poly(dimethylsiloxane) plates has been demonstrated (see picture). The strength and direction of capillary forces between plates was controlled by patterning of the surfaces of the…
6.7 Gigatonnes of silicon are processed each year by marine organisms. Since it was known that silicon is an essential element for many biological systems, significant advances in the biochemistry of this element have been achieved from the classical viewpoint of silicon being a purely inorganic element. This article…
The concept of carrier pocket engineering is applied to strained Si/Ge superlattices to obtain a large thermoelectric figure of merit ZT. In this system, the effect of the lattice strain at the Si/Ge interfaces provides another degree of freedom to control the conduction band structure of the superlattice. We explore…
The observation of localized stationary structures, coined oscillons, in granular media has evoked much interest. By parametric excitation of clay suspensions, we demonstrate a hysteretic transition to oscillon-type states in a nongranular medium. When the symmetry of up-down $\mathrm{reflection}+\mathrm{time}$ transl…
We investigate the disordering of an initially phase-segregated binary alloy, due to a highly mobile defect which couples to an electric or gravitational field. Using both mean-field and Monte Carlo methods, we show that the late stages of this process exhibit dynamic scaling, characterized by a set of exponents and s…