Materials Literature
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We investigate the homogeneous linewidth of localized type-I excitons in type-II GaAs/AlAs superlattices. These localizing centers represent the intermediate case between quasi-two-dimensional (Q2D) and quasi-zero-dimensional localizations. The temperature dependence of the homogeneous linewidth is obtained with high…
We report the electronic structure and magnetic ordering of the single molecule magnet $[{\mathrm{Mn}}_{10}{\mathrm{O}}_{4}{(2,2}^{\ensuremath{'}}\ensuremath{-}\mathrm{biphenoxide}{)}_{4}{\mathrm{Br}}_{12}{]}^{4\ensuremath{-}}$ based on first-principles all-electron density-functional calculations. We find that two of…
How can optimum long-range order be achieved by self-assembly of polystyrene/polymethylmethacrylate (PS/PMMA) block copolymers? Here the film thickness, annealing temperature, annealing time, and molecular weight are varied to derive optimum values for these parameters. The Figure shows SEM images of the microstructur…
We combine molecular dynamics simulations of deformation at the submicron scale with a simple continuum fracture mechanics model for the onset of crack propagation to calculate the macroscopic fracture energy of amorphous glassy polymers. Key ingredients in this multiscale approach are the elastic properties of polyme…
The gas of the interacted electrons is usually described within Kohn-Sham approximation by the set of Poisson and Schrödinger equations with an effective potential for the single-particle wave functions. The solution of these equations should give the self-consistent electron density distribution and Coulomb potential…
Thermodynamically stable, but kinetically labile: Trigonal-prismatic M3L2 metallocages occur in [BF4⊂{Ag3(MsTBim)2}](BF4)2 (1) and [{CuI3⊂[Cu3(MsTBim)2]}2](Cu2I4) (2), the latter with an unprecedented metal-complex-host/metal-complex-guest arrangement. Large anions such as CF3SO3− or BPh4− have to reside outside the c…
Using a variety of optical probe techniques we studied the steady state and transient dynamics of charged and neutral photoexcitations in thin films of poly-3-alkyl thiophene with regioregular order, which forms self-assembled lamellae structures with increased interchain interaction, as well as regiorandom order that…
Hollow polyaniline microspheres have been synthesized from a monomeric aniline-based template, which makes template removal unnecessary. The template for the microstructures is an aniline emulsion with β-naphthalenesulfonic acid (NSA) as dopant, and ammonium persulfate (APS) as oxidizer. The Figure is a TEM image of p…
Colloidal inks, comprised of silica microspheres with tailored attractive interactions between them, have been directly assembled via a robotically controlled deposition technique. 3D periodic lattices, whose periodicity far exceeds the dimensions of the colloidal building blocks (see Figure for a cross-sectional imag…
The grain size dependence of the “giant dielectric effect” in CaCu3Ti4O12 ceramics (arising from a semiconducting grain/insulating grain boundary microstructure) has been revealed by impedance spectroscopy of ceramics sintered for 3 h (see Figure, left) and 24 h (see Figure, right); a rise in permittivity from 9000 to…
Polymers can be theoretically and computationally described by models pertaining to different length scales and corresponding time scales. These models have traditionally been used independently of each other. Recently, considerable progress has been made in systematically linking models of different scales. This Revi…
Inorganic nanostructures that interface with biological systems have recently attracted widespread interest in biology and medicine. Nanoparticles are thought to have potential as novel intravascular probes for both diagnostic (e.g., imaging) and therapeutic purposes (e.g., drug delivery). Critical issues for successf…
We study effects of an oxygen vacancy on the electronic state of the CuO 2 plane in the normal state, on the basis of the d – p model. We calculate the local density of states at copper sites and oxygen sites around the p x -oxygen vacancy, at T = T c . The spatial distribution has a shape which oscillates along the d…
Determination of the Switching Response in Reflective Twisted Nematic Liquid Crystal Displays, Bougrioua, Fatiha, Oepts, Wouter, Vleeschouwer, Herbert De, Alexander, Els, Neyts, Kristiaan, Pauwels, Herman
The notion of random close packing (RCP) has been utilized as a guiding concept for analysis of randomly packed structure of hard spheres. The concept has been proved to be useful in many practical applications in which some elements are packed in a limited space. Carbon blacks dispersed in a solvent and colloidal sus…
Tin-doped indium oxide (ITO) thin films were deposited at room temperature by a dual-oxygen-ion-beam-assisted evaporator system and the effects of doped tin concentrations in the films on the electrical properties of the ITO films were investigated. Doped tin atoms in amorphous ITO films caused extra scattering and st…
Amorphous hydrogenated silicon carbide (a-SiC:H) films were deposited from a mixture of silane and methane gases using the plasma-enhanced chemical vapor deposition (PECVD) process. The properties of the film, following ammonia plasma treatment, are reported. A lower silane flow rate reduces the refractive index, but…
Optical properties of single-walled boron nitride nanotubes have been studied theoretically. The dielectric functions calculated from the gradient approximation and the random-phase approximation are consistent with each other. The imaginary and the real parts of the dielectric function, respectively, exihibit the spe…
We have studied an oxidation effect of multiwalled carbon nanotubes (MWCNTs) grown by thermal chemical vapor deposition (CVD) using ultraviolet photoelectron spectroscopy (UPS) and transmission electron microscopy (TEM). With an increasing oxygen exposure, the carbon 2 p -π states at ∼3 eV below the Fermi level in the…
The analysis of the different amino acid sequences deduced from the complete genome sequence of the gram-positive bacterium Staphylococcus aureus suggested the presence of two eukaryotic-protein-like low-molecular-mass phosphotyrosine protein phosphatases, which are usually found in gram-negative bacteria. To check th…