Materials Literature
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We present ab initio density-functional calculations for acceptors, donors, and native defects in aluminum nitride, showing that acceptors are deeper (Be ~ 0.25 eV, Mg_ 0.45 eV) and less soluble than in GaN; at further variance with GaN, both the extrinsic donors Si_Al and C_Al, and the native donor V_N (the anion vac…
Infra-red (IR) absorption results on irradiated and annealed synthetic diamond are presented which confirm an earlier proposal that a component found in the defect-induced one-phonon region of some diamonds arises from positively charged single-substitutional nitrogen . The concentration ratio of to neutral substituti…
Contact resistances of multiwalled nanotubes deposited on gold contact fingers are very large. We show that the contact resistances decrease by orders of magnitudes when the contact areas are selectively exposed to the electron beam in a scanning electron microscope. The focused electron beam enables the selection of…
Recent experiments in some polymer melts quenched below the melting temperature have reported spinodal kinetics in small-angle x-ray scattering before the emergence of a crystalline structure. To explain these observations we propose that the coupling between density and chain conformation induces a liquid-liquid bino…
SrCu 2 O 2 thin films were prepared on SiO2 glass substrates by pulsed laser deposition. The film deposited in O2 atmosphere of 7×10−4 Pa at 573 K showed high optical transmission in visible and near-infrared regions. Potassium was doped at Sr site for substitutional doping. The optical band gap of the K-doped film wa…
The electron affinity $\ensuremath{\chi}$ and the band diagram of single crystal diamond (111) surfaces was determined as a function of hydrogen coverage by combining work function measurements with photoelectron yield and core level photoemission spectroscopy. $\ensuremath{\chi}$ ranges from $\ensuremath{-}1.27\mathr…
Transport properties of polycrystalline Ge clathrates with general composition Sr8Ga16Ge30 are reported in the temperature range 5 K⩽T⩽300 K. These compounds exhibit N-type semiconducting behavior with relatively high Seebeck coefficients and electrical conductivity, and room temperature carrier concentrations in the…
1. An introduction to the phthalocyanines 2. Phthalocyanine synthesis 3. The fabrication of phthalocyanine materials 4. Optical properties 5. Electronic conductivity 6. Optoelectronic properties of phthalocyanine materials 7. Miscellaneous properties and uses of Pc materials 8. Future developments.
The aim of this study is to investigate the influence of temperature, initiator concentration, and vinyl monomer on silk yellowing during grafting. A series of silk fabrics was treated at four different temperatures (70, 75, 80, and 88°C), with different concentrations of initiator in the range 1–4% owf, with and with…
This article provides a method to obtain high-hoop-strength high-density polyethylene (HDPE) pipe by mandrel-rotating extrusion. With properly selected processing temperature, pressure, and mandrel-rotating speed, the hoop strength of 90 Mpa has been got. Differential scanning calorimetry and X-ray scattering found th…
Size-quantized CdS nanocrystals of controlled dimensions are synthesized within monodisperse egg lecithin vesicles made by detergent depletion. Cryo-transmission electron microscopy (cryo-TEM) enables imaging in situ both of the vesicle wall and of the encapsulated nanocrystal. Cryo-TEM images confirm that only one pa…
Polystyrene surfaces have been modified by poly( N -isopropylacrylamide) (PIPAAm) grafting. Beside observing the adhesion and the effect of low-temperature treatment on anchorage-dependent cells, the wetting behavior of PIPAAm-grafted surfaces was studied by dynamic contact angle measurement by Wilhelmy microbalances.…
Environmental scanning electron microscopy is a technique capable of imaging fluid systems in their natural state without prior specimen preparation. As such, it is potentially a very powerful tool for studying emulsion structures at a resolution significantly higher than that for conventional optical microscopy. We p…
The liquid-phase oxidation of eight fuels and a series of 1:1 blends has been studied at elevated temperature and pressure to simulate some of the chemical-reaction conditions that cause surface fouling in aircraft fuel lines. The time, t, needed to deplete dissolved O 2 by 50% was determined for each blend and compon…
Free-radical solution terpolymerization of acrylamide, acrylic acid, and acrylonitrile was carried out in a mixture of dimethylformamide and water (60 : 40,v/v) at 85°C using benzoyl peroxide as the initiator. The polymers were characterized by elemental analysis, IR, 1H-NMR, TGA, and viscosity measurements. Elemental…
A series of rigid interpenetrating polymer network (IPN) foams, based on a rosin-based polyurethane and an epoxy resin, were prepared by a simultaneous polymerization technique. The changes in the chemical structure, dynamic mechanical properties, and morphology of the rigid IPN foams were investigated by Fourier tran…
Reactions of vinyl trimethoxysilane grafting onto low-density polyethylene (LDPE) were investigated using Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermal gravimetric analysis. The silane grafting reactions were induced by a fixed amount of dicumyl peroxide at 0.2 part of reagent…
Conducting polymers with very small band gaps have been prepared by the electrochemical copolymerization of 4-dicyanomethylene-4 H -cyclopenta[2,1- b;3,4- b ‘]dithiophene ( 1 ) with 3,4-ethylenedioxythiophene ( 2 ). Strong evidence that the materials formed are true copolymers rather than polymer blends is obtained fr…
Alkyl 2-naphthyl ethers are an important class of precursors for the manufacture of fine chemicals useful as perfumery and pharmaceutical chemicals. The efficacy of solid acid catalysts such as acid-treated clays (Filtrol-24 and K-10), heteropolyacids (dodecatungstophosphoric acid, dodecatungstosilicic acid, dodecapho…
A new procedure for the preparation of nanosized In(OH) 3 particles in high concentrations without added surfactants is described. The process is based on the peptization of In(OH) 3 dispersions consisting of micrometer colloids, which are obtained by the hydrolysis of InCl 3 in ethylene glycol to which aqueous sodium…