Materials Literature
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A variational technique is developed to investigate the polaronic features of the Holstein molecular-crystal model. It is based on a linear superposition of Bloch states that describe large and small polaron wave functions. It is shown that this method provides a very good description of the regime characterized by in…
Experiments have widely shown that a steady-state lamellar eutectic solidification front is destabilized on a scale much larger than the lamellar spacing by the rejection of a dilute ternary impurity and forms two-phase cells commonly referred to as "eutectic colonies." We extend the stability analysis of Datye and La…
The stability of derivatized mesoporous silicon in a physiological environment is investigated and potential applications are discussed. It is shown that, while the surface of hydride-terminated mesoporous silicon corrodes very rapidly upon exposure to simulated body fluid (see Figure), the dodecenyl-terminated materi…
Photolysis of [M(CO) 6 ] (M = Cr, W) in the presence of BH 3 ·L (L = NMe 3, PMe 3, PPh 3 ) gave isolable borane complexes [M(CO) 5 (η 1 -BH 3 ·L)] ( 1a, M = Cr, L = PMe 3; 1b, M = Cr, L = PPh 3; 1c, M = Cr, L = NMe 3; 2a, M = W, L = PMe 3; 2b, M = W, L = PPh 3; 2c, M = W, L = NMe 3 ). In products 1 and 2, the monobora…
A Monte Carlo simulation model for the random packing of unequal spherical particles is presented in this paper. With this model, the particle radii obeying a given distribution are generated and randomly placed within a cubic packing domain with high packing density and many overlaps. Then a relaxation iteration is a…
Control of Y 2 O 3:Eu Spherical Particle Phosphor Size, Assembly Properties, and Performance for FED and HDTV, Jing, X., Ireland, T., Gibbons, C., Barber, D. J., Silver, J., Vecht, A., Fern, G., Trowga, P., Morton, D. C.
We study analytically the equilibrium and near-equilibrium properties of a model of surfaces relaxing via linear surface diffusion and subject to a lattice potential. We employ the variational mean field formalism introduced by Saito for the study of the sine Gordon model. In equilibrium, our variational theory predic…
Direct experimental evidences for excitonic lasing is obtained in optically pumped V-groove quantum wire structures. We demonstrate that laser emission at a temperature of 10 K arises from a population inversion of localized excitons within the inhomogenously-broadened luminescence line. At the lasing threshold, we es…
CuInSe2 quantum dots are reported here for the first time. The highly crystalline nanoparticles of CuInSe2 and also of CuSe were prepared by reaction in tri-n-octylphosphine oxide (TOPO), producing TOPO-capped particles that are close to monodisperse. Transmission electron microscopy shows that the particles are spher…
We have used a recently developed computational technique based on density-functional theory to study the Raman-active modes of amorphous ${\mathrm{GeSe}}_{2}$ and ${\mathrm{GeS}}_{2}.$ Vibrational modes and the associated Raman activities for three cluster building blocks of the glasses are calculated directly from f…
The ability to tailor the intercalation preferences of porous solids would have important applications in sensing, separations, and catalysis. Shape-selective intercalation is reported here for a crystalline-ordered, layered double hydroxide, whose preference for the intercalation of 1,5- or 2,6-naphthalenedicarboxyla…
Two-dimensional (2D) photonic crystals in the visible wavelength region were fabricated using anodic porous alumina with a highly ordered hole array configuration. The transmission properties of an ordered triangular array of an air cylinders with high aspect ratio in alumina matrix showed a stop band in the spectrum…
Powder diffraction techniques are becoming increasingly popular as tools for the determination of crystal structures. The authors of this paper have developed a software package, named PowderSolve , to solve crystal structures from experimental powder diffraction patterns and have applied this package to solve the cry…
Two chemical treatments were applied to hemp, sisal, jute and kapok natural fibres to create better fibre to resin bonding in natural composite materials. The natural fibres have been treated with varying concentrations of caustic soda with the objective of removing surface impurities and developing fine structure mod…
Water repellency, high surface resistivity, vandalism resistance, low density and good processability have made silicone rubbers based on polydimethylsiloxane (PDMS) very attractive materials in housings for outdoor insulation. Their ability to recover hydrophobicity after oxida. tion or contamination is of paramount…
Well-defined polycrystalline Cu 2 O was electrodeposited on transparent conducting substrates from alkaline Cu(II) lactate solutions. The morphology of the layers could be controlled by choosing the appropriate experimental conditions; the pH and temperature of the deposition solution were especially important. The gr…
Time resolved photoluminescence (PL) decays have been measured for Si nanocrystals embedded in silicon dioxide. The nanocrystals were formed by implanting 40 keV Si ions into a 1000 Å thick film of thermally grown SiO2, followed by thermal annealing at 1000–1200 °C. The observed luminescence, peaking at 700–850 nm, is…
ABSTRACT The global demand for wood as a building material is steadily growing, while the availability of this natural resource is diminishing. This situation has led to the development of alternative materials. Of the various synthetic materials that have been explored and advocated, polymer composites claim a major…
Single phase La-doped BaTiO3 with the formula Ba1−xLaxTi1−x/4O3: 0⩽x⩽0.20 was prepared by solid state reaction of oxide mixtures at 1350 °C, 3 days, in O2. The tetragonal distortion in undoped BaTiO3 decreased with x and samples were cubic for x⩾0.05. Both the tetragonal/cubic and orthorhombic/tetragonal transition te…
The Young's moduli of various oxide glasses (silicate, borate, phosphate, and tellurite) were measured using an ultrasonic method. To predict the Young's moduli of the oxide glass systems, empirical compositional parameters G i and V i , based on the Makishima‐Mackenzie theory, were obtained, where G i is the dissocia…