Materials Literature
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Molten Si was allowed to solidify isothermally at initial bulk undercoolings ΔT from 5.7 to 157 K. It was found that in addition to the 〈211〉 twin dendrites two novel dendrites were found: the 〈110〉 twin and the 〈100〉 twin free dendrite. The 〈110〉 twin dendrite has multiple twin planes, and the orientation of the twin…
Room-temperature luminescence observed in porous silicon has been attributed either to direct radiative recombination in nanometer-size silicon in the porous silicon network, or to chemical complexes of silicon, hydrogen, and/or oxygen. In this paper, we attempt to correlate results of infrared and photoluminescence s…
We present a theoretical study of the structural stability of ordered configurations of ${\mathrm{B}}_{\mathit{x}}$${\mathrm{C}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$ solid solutions with the graphite structure. The calculations were carried out self-consistently using norm-conserving pseudopotentials in the local-den…
We have used neutron reflection and phase contrast microscopy to investigate the morphology and surface topology of thin films of nearly symmetric (f=0.55) and asymmetric (f=0.77), poly (ethylene–propylene)–poly (ethylethylene) (PEP–PEE) diblock copolymers (f being the PEP volume fraction) and have identified three im…
A deterministic global optimization algorithm is introduced for locating global minimum potential energy molecular conformations. The proposed branch and bound type algorithm attains finite ε-convergence to the global minimum through the successive refinement of converging lower and upper bounds on the solution. These…
Abstract Electrochemical synthesis of polyaniline (PANI) was carried out under cyclovoltammetric conditions using H 2 SO 4 , HCl, HNO 3 , and HClO 4 as supporting electrolytes. The observed different rate of PANI deposit growth depending on the acid in the solution has been explained on the grounds of a different degr…
The ab initio full-potential linearized-augmented-plane-wave method for a free-slab geometry was used to calculate the electronic structure and geometry of a clean ${\mathrm{TiO}}_{2}$ (110) rutile surface. Surface induced states were found in the density of states, such as an s-like surface state at -15 eV. Band bend…
Time-zero current-voltage characteristics and time-dependent current behavior of metal-ferroelectric-metal (Pt-PZT-Pt) capacitor structures have been studied. Under constant-voltage stressing, the current density through the 1500-Å-thick lead-zirconate-titanate (PZT) film exhibits a power-law dependence on time, with…
Intense laser irradiation has been used to anneal porous silicon. In situ Raman spectroscopy and photoluminescence (PL) spectroscopies have been used as probes of the silicon particle sizes and temperatures, and the resulting light emission of porous silicon. Once annealed, the PL of porous silicon while at 830 \ifmmo…
A microscopic tight-binding model of the spin-dependent coupling between effective-mass electrons and localized spins in the IV-VI diluted magnetic semiconductors is proposed. Contributions from the direct Coulomb exchange as well as from the hybridization between band states and resonant levels associated with magnet…
The absorption spectrum of Ti3+:Al2O3 crystals grown in a reducing atmosphere consists of the main blue-green absorption band and a weak infrared band. This infrared absorption decreases in intensity on annealing the as-grown samples in a reducing atmosphere. The analysis of electron spin resonance spectra of the as-g…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThin silver films: influence of substrate and postdeposition treatment on morphology and optical propertiesShane E. Roark and Kathy L. RowlenCite this: Anal. Chem. 1994, 66, 2, 261–270Publication Date (Print):January 15, 1994Publication History Published online1 May 2002Publ…
The dielectric constant and ac conductivity of rf-sputtered insulating zinc oxide films has been measured in the metal-insulator-metal configuration over a wide temperature (90--500 K) and frequency (0.1--100 KHz) range. The films sputtered from oxide targets in argon were c-axis oriented having a resistivity of \ensu…
The transitional properties of the liquid crystal dimers formed by two mesogenic groups linked by a flexible chain exhibit a pronounced dependence on the number of atoms in the spacer. Here we present the results of a theoretical calculation of the nematic–isotropic transition temperature, the entropy of transition, a…
We report the dependence of the microwave-frequency dielectric constant and dc conductivity on the crystallinity and local order of doped polyaniline. The dramatic increase of the dielectric response in the three highest crystalline physically crosslinked polyaniline samples provides evidence for the formation of thre…
We present a study of the electrical transport in porous Si layers prepared by anodic etching of two different kinds of (100) p-type Si substrates. It is shown that by choosing a sufficiently thick layer, the problem of injection from the contacts can be eliminated. In this way we measure the intrinsic transport prope…
Cathodoluminescence has been investigated in diamond films, prepared by microwave plasma assisted chemical-vapor deposition. Results are presented for various diamond films differing in crystalline structure and doping. In the energy range 2.0--2.7 eV a series of 13 sharp luminescence lines has been observed at temper…
A general and practical model for heat generation that can be used in the heat conduction equation for nonisothermal semiconductor device simulations is presented. The model is developed for cubic semiconductors with position-dependent, multivalley, and multiband band structures, Fermi-Dirac statistics and an accurate…
Abstract When 4,4'‐bis (3,4‐dicyanophenoxy) biphenyl is heated with small amounts of aromatic amine or amidine salts, a highly crosslinked polytriazine is obtained. This polymer has been shown to be the same as that reported when bisphthalonitriles are heated with amines. Salts promote this reaction more readily and t…
Photoemission and bremsstrahlung isochromat spectra have been measured on TiO 2 (rutile) and SrTiO 3 . The magnitudes of the fundamental band gaps estimated from the combined spectra agree well with the results of the photoabsorption and the energy-band calculations. The profiles of the observed spectra do not reveal…