Materials Literature
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Abstract The thermal properties of silver powder‐filled polypropylene composites were studied as a function of filler concentration. Thermal conductivities of the composites increased with filler content. Comparison of the data with theoretical predictive models for two‐phase systems showed that the Nielson equation a…
Enhancement of the conductivity of zinc oxide through doping with hydrogen atoms was examined by using ion implantation of highly resistive thin films deposited by rf magnetron sputtering at room temperature. With a doping of 1×1017 atoms cm−2, the conductivity after annealing at 200 °C in an N2 atmosphere at 1 atm ro…
The properties of thin films of Cu-doped with different percentages of Mg were investigated. It was found that as-deposited films of Cu (2 at. % Mg) oxidize orders of magnitude more slowly than do those of pure Cu. More importantly, when Cu(2 at. % Mg) films are annealed in Ar at 400 °C for 30 min, a thin protective l…
A highly tetrahedral, diamond-like form of hydrogenated amorphous carbon (a-C:H) with density of 2.9 g cm−3, sp3 fraction of 0.75, and hardness of 61 GPa, the highest values so far attained from a hydrocarbon source gas, has been deposited from acetylene in a novel plasma beam source. The ion energy for highest sp3 fr…
We report the fabrication by PECVD of silicon-rich erbium-doped silica films that exhibit both 1535 nm fluorescence and visible photoluminescence. Fluorescence spectra are presented along with absorption spectra that display a strong band edge in the blue, which we ascribe to the presence of Si microclusters. We are u…
We report the first room-temperature sharp line electroluminescence of an erbium-doped silicon light-emitting diode at λ=1.54 μm. The electroluminescence originates from an internal f-shell transition of Er3+. The wavelength and linewidth are relatively independent of temperature. The light intensity saturates at a dr…
The electronic and structural properties of ${\mathrm{VO}}_{2}$ across its metal-insulator transition are studied using the local-density approximation. Band theory finds a monoclinic distorted ground state in good agreement with experiment, and an almost open gap to charge excitations. Although rigid criteria for dis…
A new class of porphyrin-based chromophore systems has been prepared from ethyne-elaborated porphyrin synthons through the use of metal-mediated cross-coupling methodologies. These systems feature porphyrin chromophores wired together through single ethynyl linkages. This type of topological connectivity affords excep…
Abstract Cyclotrimerization of phenyl isocyanate in the presence of various catalysts was studied. All reactions were carried out in 1,4‐dioxane at 30–50°C. Reaction products were determined by reverse‐phase liquid chromatography. 1,3,5‐Triphenyl isocyanurate was formed and also traces of 1,3‐diphenylurea and 1,3,5‐tr…
Reorientations of Fe3+ spins have been studied in TbFeO3 single-crystal absorbers by Mossbauer spectroscopy. At low temperature we observed two closely spaced changes of direction of the Fe3+ spins. Below 6.5 K the spins moved from the a towards the c orthorhombic axis with decreasing temperature. This movement was re…
The crystal structures and Mössbauer spectra of various mixed oxides LaFe1−xMnxO3 and LaFe1−xCoxO3 (x = 0 to 0.9) are determined and measured at room temperature. The results indicate that the crystal structure of both the La–Fe–Mn–O and the La–Fe–Co–O systems vary with the relative content of manganese and cobalt in…
Neutron diffraction experiments over the momentum transfer range 0<Q(AA) -1 <40 have been used to investigate the structural properties of liquid sulphur from 140 degrees C up to 300 degrees C, i.e. from conditions near the melting point of sulphur up to temperatures well above its lambda -transition (T lambda =159 de…
Abstract Morphology–property relationships for simultaneously biaxially stretched films and heatset with fixed dimensions in the temperature range of 100–240°C have been studied. The observed transition in various properties at 180°C can be explained on the basis of microstructural changes caused by competition among…
Heteroepitaxial growth of tin-doped indium oxide (ITO) film was achieved for the first time by using single crystalline yttria stabilized zirconia (YSZ) as substrates. The epitaxial relationship between ITO film and YSZ substrate was ITO[100]∥YSZ[100]. By comparing the electrical properties of this epitaxial ITO film…
We propose a mechanism for creating lateral order in thin films of a homopolymer mixture via spinodal decomposition in the presence of a laterally structured substrate surface. The system under consideration is a mixture of deuterated polystyrene and partially brominated polystyrene (PBrxS, x=0.5) spuncast onto differ…
Abstract Three conventional polyurethane (PU) elastomers were blended physically with various ratios of high molecular weight of poly(4,4′‐diphenylsulfone terephthalamide) (PSA) to form 12 PU/PSA polyblends in order to modify their physical properties. Also three new polyurethanes were synthesized with a low‐molecular…
Abstract Polyurethanes were synthesized from polyester polyols, derived from PET Waste. The PET waste was first depolymerized by glycolysis. The glycolysized products were reacted with adipic acid to yield polyester polyols, and the polyester polyols were then reacted with either MDI or TDI to obtain polyurethanes. In…
Deep level transient spectroscopy (DLTS) has been used to investigate trap levels in sol-gel derived polycrystalline Pb(Zr0.54,Ti0.46)O3 thin films. Metal-ferroelectric-metal capacitor structures 2400 and 3000 Å in thickness were fabricated and characterized using a constant voltage DLTS system. Prominent peaks associ…
Transparent conducting cadmium oxide films are prepared by the spray pyrolytic technique. The dependence of structural, optical, and electrical properties on the film thickness is investigated. X-ray diffraction studies confirm the polycrystallinity of the films and the films show preferential orientation along the (2…
A diamond field emitter array has been fabricated. by Chemical vapor deposition. Diamond was grown on an inverted pyramidal-shape Si substrate followed by removal of the substrate. The fabricated array was placed in a high vacuum pumping system with the pressure of ∼10−7 Torr and the emission current as a function of…