Materials Literature
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Infrared reflectivity spectra of sintered crystal CdCr2S4 have been measured in the temperature range of 15–300 K. The frequencies of transverse and longitudinal phonon modes were determined from the spectra with the Kramers–Kronig relation. The temperature dependencies of those showed anomalously large shifts near th…
The intensities of vibrational resonance hyper-Raman transitions are developed in the usual framework of vibronic theory. In analogy to linear Raman scattering, the leading terms of RHR scattering, A, B, and C, are found when the electronic transitions moments, appearing in the transition hyperpolarizability, are expa…
The values of the optical constants of magnesium fluoride (MgF(2)) and zinc sulfide (ZnS) thin films are obtained using a classical oscillator model and the experimental values of their spectral transmittance. Auger electron spectroscopy was performed on the samples to determine the chemical composition of the films.…
Two approaches to the growth of high-quality epitaxial Ge epilayers on (100) Si have been investigated. The first consisted of compositional-grading Si1−xGex layers and the use of strained-layer superlattices as dislocation filters. In general, this method produced unsatisfactory results, due to the difficulty in achi…
The optical properties of extremely small isolated semiconductors provide a sensitive probe of the developing electronic structure in the materials. Cadmium sulfide and ${\mathrm{CdS}}_{\mathrm{x}}$${\mathrm{Se}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ crystallites are precipitated in an insulating glass matrix during a…
A new band-structure method which allows the self-consistent solution of the Schr\"odinger equation with a full (all-electron, non-muffin-tin) crystal potential has been developed. A basis set consisting of the 9 (16) s, p, and d (f) linear-muffin-tin orbitals per site is used. The wave functions as well as the electr…
Many liquids have heat capacities that substantially exceed those of the corresponding crystal, and this discrepancy magnifies in the supercooled regime. Thus, liquid entropy declines more rapidly with temperature than does crystal entropy, and the former paradoxically seems to fall below the latter for temperatures b…
Films of ZnO:Al were produced by weakly reactive dual-target magnetron sputtering. Optical band gaps, evaluated from spectrophotometric data, were widened in proportion to the Al doping. The widening could be quantitatively reconciled with an effective-mass model for n-doped semiconductors, provided the polar characte…
The liquid-fluid tension at the edge of a liquid drop may provoke a wetting ridge on a sufficiently soft solid substrate. Many soft solids such as polymers, and in particular elastomers, are viscoelastic and display hysteretic characteristics in a strain cycle. Such a strain cycle can be present near the advancing wet…
A smecticlike structure of a simple liquid adjacent to a solid surface gives rise to an attenuating oscillating potential in which the free surface of the film fluctuates. These capillary fluctuations lead to critical wetting phenomena of an earlier unknown origin. The corresponding wetting, layering, and surface melt…
Infrared diode laser absorption spectroscopy is employed as an in situ method to examine gas phase species present during filament-assisted deposition of diamond films. From a reactant mixture of 0.5% methane in hydrogen, methyl radical (CH3 ), acetylene (C2H2), and ethylene (C2H4 ) are detected above the growing surf…
Abstract This paper presets a new mathematical formulation chat provides a realistic and appropriate representation of foam behaviour in a porous medium. Foams are gaining increasing importance in the petroleum industry in a number of roles, notably as mobility control and/or blocking agents in enhanced oil recovery o…
A systematic study of the infrared photoluminescence from deep centres in polycrystalline CdSe layers is presented. The authors observe two emission bands at about 0.92 mu m and about 1.22 mu m. The evolution of the band shape and emission intensity quenching with temperature is analysed using a semiclassical model, a…
Hot pressed composites of Si3N4 containing 30% SiC whiskers have shown substantial improvements in strength and fracture toughness relative to monolithic silicon nitride. Injection molded samples made of this composite material distorted in a systematic manner during densification by hot isostatic pressing. Whisker or…
Thermal barrier coatings (TBC) have been used in jet engine combustors for over 15 years. However, it is only recently that they have been actively used in the harsh turbine environment on nozzle guide vane platforms. It is intended to use TBCs on vane airfoils, and on rotating turbine blades where the maximum payoff…
The observation of optical and electric first-order Freedericksz transitions in a homeotropically aligned nematic liquid crystal film induced by electric and optical fields, respectively, is reported. The experimental results are in good agreement with theoretical predictions.
We present the first precise characterization of the profile of the precursor films which progressively develop ahead of the macroscopic edge of a spreading liquid drop. Experiments are performed on a model system (nonvolatile high-molecular-weight polydimethylsiloxane on smooth silicon wafers), using an ellipsometer…
Abstract The effects of water‐soluble and monomer‐soluble impurities on the kinetics of emulsion polymerization of monomers following Case II kinetics (e.g., styrene) are investigated. Experimental studies reveal that impurities can have an appreciable effect on both polymer particle nucleation and growth. These effec…
Abstract The development of new methods of spinning cellulosic fibers requires a better understanding of their fibrillar structure in order to explain their special physical properties. By means of transmission electron microscopy (TEM), light microscopy (LM), small‐angle X‐ray scattering (SAXS), and wide‐angle X‐ray…
Abstract Various amounts of a styrene‐butadiene‐based triblock copolymer (SEBS) was used to compatibilize immiscible blends of high density polyethylene (HDPE) and an amorphous glassy phase consisting of either pure polystyrene (PS) or a miscible blend of PS and a polyether copolymer (PEC). PEC is structurally similar…