Materials Literature
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ZnO films that have been used as active layers of optically pumped lasers are investigated by a number of optical and photoelectric techniques, such as transmission, reflectivity, photoluminescence and direct and alternating photocurrents. Homogeneity with respect to “bulk” and surface properties is evaluated. The spe…
Electrolytes formed with poly(oxyethylene), POE, and europium picrate, [Eu(pic)2(OH2)6]pic.6H2O (where pic denotes the picrate anion) or simply Eu(pic)3xH2O, have been investigated by infrared and photoluminescence spectroscopies. The complexes have been represented by POEnEu(pic)3xH2O (where n represents the molar ra…
1 H-NMR, EPR and static magnetic susceptibility measurements have been performed on an organic conductor, θ-(BEDT-TTF) 2 CsZn(SCN) 4 . The 1 H-NMR- T 1 -1 and the spin susceptibility exhibit anomalous enhancements at low temperatures. Around 20 K, where the spin susceptibility shows a minimum, the principal axes of th…
Dielectric breakdown of (Pb,La)(Zr,Ti)O3(PLZT) film capacitors with Pt and SrRuO3 electrodes, in its initial or virgin state and after voltage cycling that causes polarization fatigue, is studied by constant-current measurements. It is shown that for different types of PLZT capacitors, the breakdown onset is controlle…
Coupling nanocrystals (quantum dots) to a high-$Q$ whispering gallery mode (WGM) of a silica microsphere, can produce a strong coherent interaction between the WGM and the electronic states of the dots. Shifting the resonance frequencies of the dots, for instance by placing the entire system in an electric potential,…
The Fermi surface (FS) of $2H\ensuremath{-}{\mathrm{TaSe}}_{2}$ was investigated by high resolution angle resolved photoemission. Two FS pockets, one centered at the \ensuremath{\Gamma} point and the other centered at the K point, were observed and are found to be in excellent agreement with the band calculation resul…
Second-harmonic generation, one of the second-order nonlinear optical properties of thermally and electrically poled WO>(3)-TeO>(2) glasses, has been examined. We poled glass samples with two thicknesses (0.60 and 0.86 mm) at various temperatures to explore the effects of external electric field strength and poling te…
The dilatometric curves of 21 epoxide–amine network samples made from five distinct epoxide–amine pairs, with variable amine/epoxide functional ratio values for three of these pairs, were recorded in the 200 K to Tg (glass-transition temperature) − 50 K temperature range. The curves display a quasiparabolic shape cons…
The thermal decomposition behavior of six derivatives of maleated polyethylene was investigated by high-resolution pyrolysis gas chromatography–mass spectrometry. The results revealed that substituents attached to maleated polyethylene as amides formed from secondary amines were significantly less stable than imides f…
A polymer film surface modified by laser illumination was used as a command surface for nematic liquid crystal (LC). Azobenzene-containing polyurethanes were taken for the material of the film. A relief grating inscribed by laser illumination onto the surface of these polymers induced a reorientation of the LC directo…
Droplets of Ga24Mg36Zn40 were solidified in a 3 m, helium-filled drop tube. The solidified droplets contained uniformly distributed MgZn2 dendritic primary crystals, whose number was determined as a function of droplet size. A new model for the solidification in a gas-filled drop tube was developed. It allows introduc…
An electrically heated platinum filament mounted inside a quartz tube was used as a high temperature flow reactor for methane pyrolysis. The reaction products included carbon and a mixture of hydrocarbons, mainly C1−C5 alkanes, alkenes, and benzene. The hydrocarbons were measured by gas chromatography and the carbon g…
Direct ion beam deposition was successfully applied for the nucleation of nanodiamond crystallites on mirror-polished Si(001) substrates. Low-energy (80--200 eV) argon, hydrocarbon, and hydrogen ions from a Kaufman ion source were used. An amorphous carbon film was deposited on the substrate after ion bombardment. The…
The low-frequency electronic excitations of a two-dimensional graphite sheet are studied within the self-consistent-field approach. A zero-gap graphite sheet only exhibits the interband e-h excitations at zero temperature. Electrons and holes grow rapidly as temperature increases from zero. Temperature induces the int…
Electromigration-induced flow of islands and voids on the Cu(001) surface is studied at the atomic scale. The basic drift mechanisms are identified using a complete set of energy barriers for adatom hopping on the Cu(001) surface, combined with kinetic Monte Carlo simulations. The energy barriers are calculated by the…
Magnetite (Fe3O4) films and multilayers were grown using plasma-assisted molecular beam epitaxy and result in single-phase films grown in registry with a MgO substrate. No evidence of interdiffusion is detected on as-grown films. Both structural and magnetic probes indicate behaviors expected for a magnetite thin film…
Oxygen K near-edge x-ray-absorption fine-structure (NEXAFS) of polycrystalline and film ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CoO}}_{3\ensuremath{-}\ensuremath{\delta}}$ at room temperature was studied using fluorescence yield techniques. The bulk-sensitive nature of fluorescence yield (relative t…
A new and efficient synthesis of meso-linked porphyrin-quinone dyads and quinone-porphyrin-quinone triads has been developed via the intermediacy of porphyrins bearing 3-cyclobutenyl-1,2-dione and 3-(1-ethenyl)cyclobutenyl-1,2-dione substituents at one or two nonadjacent meso-positions. The free-base porphyrins 5-brom…
The temperature dependence of the current–voltage characteristics of Ba0.5Sr0.5TiO3 (BST) thin-film capacitors was studied from 300 to 433 K. An Au/BST/Pt/Ti/SiO2/Si structure was used. The BST films were deposited by rf magnetron sputtering. The conduction current was dominated by Schottky emission at room temperatur…
A microscopic model describing the electronic structure of carbon nanotubes formed from two-dimensional disordered graphite sheets is presented. The strong electronic-lattice coupling of states near the Fermi energy is shown to result in the formation of an energy gap. The model predicts that the energy gap in these t…