Materials Literature
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We study electron-phonon coupling in the case of Fr\"ohlich or polar interaction, with special emphasis on the size dependence of the coupling strength for semiconductor nanospheres exhibiting quantum confinement of the carriers. We first derive the expression of the vibrational LO (longitudinal optic) and SO (surface…
The paper presents results of experiments undertaken to elucidate the behaviour of polyethylene under the influence of high electric fields. Especially when using virgin samples, some 'anomalies' occur that are a result of a slow transition of the polymer to a preloaded state. It is shown that if two sets of traps are…
In recent years investigations of the use of digital evaluation of partial discharges have become increasingly important. Such methods of evaluation greatly improve the recognition of discharge patterns and the correlation of these patterns with various types of defects. Conventional methods of oscillographic observat…
Measurements of electrical breakdown, high-field conduction current and pre-breakdown current are made on various kinds of polymeric insulating films. The experimental results on electrical breakdown and conduction indicate that the electrical breakdown current starts to increase rapidly at about 1 ms before breakdown…
The time dependence of the discharge processes in dielectric bounded voids of 40 mm have been studied under power frequency voltage. Fast oscilloscopic techniques were used to observe the pulse shape of single discharges or clusters of discharges. Synchronous optical registration of discharge images was performed usin…
A narrow size distribution of irregular aluminium particles was blended into power cable insulation grade polyethylene. Some batches of the resulting material were then melt-filtered to reduce the size of particles present and narrow the distributions further. The failure statistics of the loaded polymers were then de…
The photoluminescence of Ti-doped sapphire (Ti:Al 2 O 3 ) crystals excited using the second (532 nm) and fourth (266 nm) harmonics of a high power pulsed Nd:YAG laser has been investigated. Excitation at 532 nm into the crystal field band of Ti 3+ produces the well known broad infrared emission band corresponding to t…
Energy gap and hydrogen concentration have been measured in hydrogenated amorphous carbon (a-C:H) after bombardment with 100 keV He+ and 300 keV Ar+ ion beams, up to ion fluences 3×1016 ions/cm2. a-C:H films have been obtained by ion irradiation at low ion fluences of polystyrene layers and with a subsequent low-tempe…
Direct measurements of the surface recombination velocity (SRV) on etched InP(110) and at its interfaces with various metals deposited by thermal evaporation have been performed using ultrafast time-resolved photoluminescence. The results show that the original InP low SRV is retained when these surfaces are coverd wi…
We report the growth of epitaxial τ-MnAl ferromagnetic films on GaAs substrates by molecular beam epitaxy (MBE). Reflection high-energy electron diffraction and x-ray diffraction show that the τ-phase films grow with the c axis of the tetragonal unit cell normal to the {100}GaAs substrate surface. In the bulk, τ-MnAl…
We describe a new type of color display consisting of polymer-dispersed droplets of chiral liquid crystal having negative dielectric anisotropy. In the field-off state, the droplets scatter light randomly. In the field-on state the droplets selectively reflect a bright color. Measurements of reflectivities and switchi…
The temperature dependence of the room pressure Raman spectra of the GeO 2 (hexagonal and tetragonal) and SiO 2 (quartz, coesite, and stishovite) polymorphs is presented. Several transformations upon heating are reported: α‐β quartz, coesite‐cristobalite, stishovite‐silica glass (with Si in four‐fold coordination). Fo…
Abstract Surface properties of fluoroalkylsilicone—poly(methyl methacrylate) block copolymers and their poly(methyl methacrylate) (PMMA) blends have been intensively studied to draw a relationship between surface segregation behavior and adhesion performance. The fluoroalkylsilicone—PMMA block copolymers containing th…
Abstract The charge transfer (CT) interactions between polyemeraldine (PEM) and six organic electron acceptors were studied. The complexing ability of the acceptors, based on the maximum attainable electrical conductivity of the resulting complex, could be arranged in the following ascending order:tetrachloro‐ p ‐benz…
Abstract The zone‐drawing method has been applied to prepare ultra‐high modulus polyvinyl alcohol fibers. First, the suitable temperature for zone‐drawing was decided. In the first zone drawing, when drawing temperature was as high as near melting point, the highest draw ratio and modulus were obtained. The modulus wa…
Abstract The thermal degradation of polystyrene (PS) in various kinds of solvents was studied in the temperature range from 300 to 450°C. The conversion of PS to low molecular weight products was dependent on the hydrogen donating ability of the solvents used: Solvents with greater donating ability resulted in less co…
Abstract The effect of a remote nitrogen plasma on polyethylene and polystyrene was studied. The gas flow rate, the dilution of reactant gas, exposure times, and reactor base pressure were all found to have a large impact on the efficiency of nitrogen incorporation. Optimum conditions caused 18 atom % nitrogen to be i…
High dielectric constant SrTiO3 thin films were sputter deposited on barrier layers/Si substrate to fabricate a capacitor for dynamic random access memories. Dielectric constant (εr) values of 140–210 were achieved for the 150-nm-thick SrTiO3 films using a Pt/Ti or Pt/Ta double-layer barrier. In the Pt(50 nm)/Ti(10 nm…
Molecular-dynamics simulations of highly nonspherical rodlike and platelike molecules reveal that one of the two diffusion coefficients in the nematic-liquid-crystal phase increases with density, reaches a maximum, and decreases, while the other coefficient decreases monotonically in the usual way. This effect seems t…
The authors describe the application of the reverse Monte Carlo simulation technique to the analysis of EXAFS data. This technique generates a series of three dimensional particle configurations which are consistent with the experimental EXAFS spectrum. No input information other than the density and the chemical comp…