Materials Literature
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The size dependence of the contribution to the excitonic dephasing rate in semiconductor nanocrystals is clarified for various electron-phonon coupling mechanisms. On the basis of these dependencies, the commonly observed linearly temperature-dependent term of the excitonic dephasing rate and the proportionality of it…
Abstract Blends of poly(vinyl chloride) (PVC) and epoxidized natural rubber (ENR) were prepared by melt‐blending and studied using a Monsanto rheometer, infrared spectrophotometer, and dynamic mechanical analyzer. The PVC/ENR blends were found to be self‐crosslinkable, but immiscible at 25/75, 50/50, and 75/25 blend r…
静的破砕剤は, 岩盤やコンクリートの解体に広く用いられているが, 最も重要なのは, ボーリング孔中の膨張圧の挙動をいかに正確に把握するかである. 本研究ではまず, ボーリング孔中の膨張圧の直接的測定方法を開発し, それを用いて膨張圧に及ぼす各種要因とそれらに対する膨張圧の挙動について検討を行った. その結果, 1) 膨張圧はあまり拘束度の影響を受けず, 2) 液圧的伝播をする, 3) 周囲の温度の影響が顕著であるが, 温度が変化しても水和率が同じであれば, 膨張圧は同じである等のことを明らかにした.
The dynamics and spectroscopy of silicon nanocrystals that emit at visible wavelengths were analyzed. Size-selective precipitation and size-exclusion chromatography cleanly separate the silicon nanocrystals from larger crystallites and aggregates and provide direct evidence for quantum confinement in luminescence. Mea…
The electrical properties of nitrogen-containing amorphous hydrogenated carbon layers are investigated. The nitrogen concentration was between 0 and 6 at%. The electrical conductivity is found to increase with the nitrogen content. The temperature dependent conductivity in the temperature range between 150 and 350 K c…
Push-pull fatigue deformation of 99.999 Al polycrystals is performed at room temperature at strain amplitudes in the range (25 to 800) × 10−6. Variations of the stress σ, energy loss ΔE, and ultrasonic attenuation Δα versus cycle number N under various push-pull fatigue strain amplitude εa are measured systematically,…
The alloys with composition around Sm11.5Co58.4Fe22.5Cu5.3Zr2.4 (at%) present hard magnet properties when their microstructure consists of a network of cells based on Sm2(Co, Fe)17, limited by boundaries based on Sm(Co, Cu)5 and cut by platelets based on (Sm, Zr)Co3. The genesis of this microstructure is studied by tr…
Dimolybdenum dithallium diphosphate, Tl 2 Mo 2 P 2 O 11 , is isotypic with K 2 Mo 2 P 2 O 11 . Its framework is built from the original Mo 2 P 2 O 15 unit, formed by one Mo 2 O 11 group sharing four of its corners with two PO 4 tetrahedra, leading to [Mo 2 P 2 O 13 ]∞ chains running along c. The [Mo 2 P 2 O 11 ]∞ fram…
Pulsed laser ablation from oxide surfaces in hydrogen atmosphere is shown to be a powerful new method for deposition of high quality metal films. Specifically, the cases of ablation from CuO and α-Fe2O3 are studied. By examining the effects of hydrogen pressure, laser energy density, and the substrate temperature on t…
Abstract This work deals with the heat treatment of fibers and nonoriented specimens made of the thermotropic liquid crystalline polymer Vectra A900 in the light of tensile properties and DSC measurements. In calorimetric measurements, there seem to be some differences in the effects of the treatment between macroscop…
We utilize a geometric argument to determine the effects of boundary scattering on the carrier mean free path in samples of various cross sections. Analytic expressions for samples with rectangular and circular cross sections are obtained. We also outline a method for incorporating these results into calculations of t…
The mechanisms responsible for the core-level binding-energy (BE) shifts that occur for surface and bulk atoms of the Al(100) surface are identified and characterized through theoretical analyses of the surface electronic structure. Two initial-state mechanisms are shown to be responsible for the shifts of the surface…
An EL5-like trap in metalorganic vapor-phase epitaxially grown GaAs:Sb has been detected by deep-level transient spectroscopy. The trap behavior has been investigated by changing the growth conditions—the V/III ratio and the level of isoelectronic doping with Sb. It has been found that the activation energy of the EL5…
A method for solving wave propagation problems in bounded media that operates entirely in wave-vector space is presented. No boundary conditions are used in the solution in contrast to the real-space method. The transmission/reflection problem of an electromagnetic wave on a dielectric half-space is solved as an illus…
Passivating films were grown on gallium arsenide by direct nitridation with hydrazine at 300–400 °C. Auger electron spectroscopy and x-ray photoelectron spectroscopy analysis show that the films are primarily gallium nitride with an oxide impurity. The oxide content is a function of the surface pretreatment, reaction…
We review mixing and phase separation (demixing) in mixtures of low molecular weight liquid crystals (LCs) and organic matrices, with emphasis on aspects relevant to the formation of polymer-dispersed liquid crystal films. These films, which contain a myriad of micron-sized LC droplets, are of interest because of thei…
A formalism is presented for determining the magnetoelastic (ME) coefficients of tetragonally distorted surfaces and thin films. The equation of motion of the magnetization is determined from free-energy-density expressions containing terms for crystalline and shape anisotropy, ME anisotropy, and applied field. Canoni…
A symmetric phase-field model is used to study directional solidification in two and three dimensions. Numerical evidence of tip-splitting, breathing modes, solitary modes, and other non-steady-state behavior is seen in 2D. A simple model for the breathing modes is proposed. Finally, 3D simulations indicate a hexagona…
The dc electrical conductivity (\ensuremath{\sigma}) of activated carbon fibers (ACF's) heat treated at temperatures (${\mathit{T}}_{\mathrm{HT}}$) ranging from 300 to 2500 \ifmmode^\circ\else\textdegree\fi{}C has been measured from 4.2 K to room temperature, and the magnetoresistance of these same fibers has been mea…
Using the x-ray excited optical luminescence technique, we have investigated the soft x-ray induced photoluminescence of porous silicon in the optical region (200–900 nm) and the Si K-edge x-ray absorption fine structures of porous silicon in the near edge region. It is found that while porous silicon prepared at low…