Materials Literature
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In semiconductor spintronic devices, the semiconductor is usually lightly doped and nondegenerate, and moderate electric fields can dominate the carrier motion. We recently derived a drift-diffusion equation for spin polarization in the semiconductors by consistently taking into account electric-field effects and nond…
Using the standard tight binding model of 2D graphite with short range electron repulsion, we predict a gapless spin-1, neutral collective mode branch below the particle-hole continuum with energy vanishing linearly with momenta at the Gamma and K points in the Brillouin zone. This spin-1 mode has a wide energy disper…
A series of star- and cone-shaped dendritic multiporphyrin arrays, (nPZn)4PFB and (nPZn)1PFB, respectively, that contain energy-donating dendritic zinc porphyrin (PZn) wedges of different numbers (n = 1, 3, and 7) of the PZn units, attached to an energy-accepting free-base porphyrin (PFB) core, were synthesized by a c…
Recent experimental results demonstrate that substantial improvements in the mechanical behavior of polymers can be obtained using very small amounts of carbon nanotubes as a reinforcing phase. Here, a method is developed to incorporate the typically observed curvature of the embedded nanotubes into traditional microm…
The layer-by-layer deposition method to prepare multilayers of polyelectrolytes of alternating charge has been followed in situ by means of optical reflectometry experiments. It turns out that in solutions containing both polyelectrolyte and appropriate salts up to a certain concentration, the regular build up of mult…
Theoretical predictions of the benefits of three-dimensional quantum confinement have provided motivation for the development of quantum-dot lasers. Such lasers, developed in the case of self-assembled quantum dots, have not been successfully demonstrated with quantum-confined colloidal nanocrystals (NCs). Here, using…
Structural and electronic properties of ${\mathrm{CaCu}}_{3}{\mathrm{Ti}}_{4}{\mathrm{O}}_{12}$ are calculated using density-functional theory within the local spin-density approximation. After an analysis of structural stability, zone-center optical phonon frequencies are evaluated using the frozen-phonon method and…
Abstract The preparation and properties of poly(vinylidene fluoride) (PVDF)/clay nanocomposites are reported for the first time. PVDF/clay nanocomposites were prepared by melt intercalation with organophilic clay. The composites were characterized with X‐ray diffraction, differential scanning calorimetry, and dynamic…
We report on ferromagnetic characteristics of Zn1−xMnxO (x=0.1 and 0.3) thin films grown on Al2O3(00⋅1) substrates using laser molecular-beam epitaxy. By increasing the Mn content, the films exhibited increases in both the c-axis lattice constant and fundamental band gap energy. The Curie temperature obtained from tem…
The processes for the selective oxidation of olefins have long been among the most useful tools for day-to-day organic synthesis. Herein, the focus is on the asymmetric-epoxidation (AE) and asymmetric-dihydroxylation (AD) reactions developed by Sharpless and co-workers. The reactions have a wide scope, are simple to r…
With an average diameter of 150−340 nm and a conductivity of 10 -1 −10 0 S/cm, nanostructures (e.g., nanotubes or nanorods) of polyaniline (PANI) were synthesized by a self-assembly method in the presence of inorganic acids (e.g., HCl, H 2 SO 4, HBF 4, and H 3 PO 4 ) as dopants. It was found that the morphology, size,…
Temperature dependent electron mobility measurements are reported for lightly doped n-type gallium arsenide (GaAs) grown by metal organic chemical vapor deposition (MOCVD GaAs). Using the Brooks–Herring model, the charge state of the impurity scattering centers is deduced to be 1. The same measurements are reported fo…
The temperature dependence of emission intensity of the Eu3+ ion in several silicate glasses was investigated between 77 and 670 K, under the excitation of a 488-nm laser. It was observed that in some glasses the total emission intensity of the Eu3+ ion had a maximum at a certain temperature below 670 K, while in the…
Experimental data for inductive cross shaped metal meshes with periodicity constant g=20 μm have been reproduced by the Micro-Stripes simulation program for various thicknesses. A similar calculation has been performed with the Fourier modal method for cross shaped meshes with periodicity constant g=1 μm. The transmit…
The thermoelectric properties of the binary quasicrystal Cd 84.6 Yb 15.4 and its approximant Cd 6 Yb are reported. The thermopowers decrease linearly from 14 and 12 µV/K, respectively, with decreasing temperature from 300 K. The resistivities at 300 K are 180 and 150 µΩ·cm, respectively, and decrease rapidly on coolin…
The exact expressions for defining the critical point of ferroelectric thin films as a function of temperature, film thickness and some other parameters are obtained on the basis of the Tilley–Zeks model. The cases of symmetric and asymmetric extrapolation lengths at the two surfaces of films are investigated. The tra…
Results are reported on the electron field emission properties of sulfur (S)-incorporated nanocrystalline carbon (n-C:S) thin films grown on molybdenum (Mo) substrates by hot-filament chemical vapor deposition (HFCVD) technique. In addition to the conventionally used methane (CH4) as carbon precursor with high hydroge…
The transient variations of a voltage holding ratio (VHR) with the progression of frames have been measured for two typical nematic liquid crystals (LCs), ZLI-4792 containing few ionic impurities and 5CB containing many more residual ionic impurities. Characteristic transient variations of the VHR were observed for bo…
Systematic dc and ac magnetic susceptibility studies have been performed on single-phase LaNi0.2Co0.8O3 powder samples. Evidence of hysteresis loops supports the existence of ferromagnetic correlations that lead to a rapid increase of the dc susceptibility at T⩽55 K. The frequency dependence of the ac susceptibility i…
Optical phonons of the ferroelectric-semiconductor Zn 1- x Li x O ceramics have been studied for several Li-concentrations as a function of temperature by using a micro-probed Raman scattering. With Li-doping, the Raman peak position of the A 1 ( z ) mode at 380 cm -1 shifts to a lower frequency side while the E 2 mod…