Materials Literature
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ZnSe epilayers were grown on GaAs (001) substrates by metal organic chemical vapor phase deposition, using different group VI–II precursor flow ratios. Atomic force microscopy (AFM) examinations of their surface show that epilayers grown with a high VI/II ratio are not as stable as those grown with a low ratio. When e…
Electrodeposited polypyrrole films were formed on chemically modified hydrogen-terminated silicon surfaces that expose tethered pyrrole units. Semiconductor/polypyrrole junctions on the native and modified substrates exhibit diode-like characteristics, with those on the latter substrate exhibiting higher current densi…
Crystalline silicon nanoparticles (quantum dots) with diameters around 4 nm are produced via CO2-laser-induced decomposition of SiH4 in a flow reactor and subsequently transferred into a freely propagating cluster beam. Thin structured films are then obtained by shaping the beam with a mask and depositing the nanoclus…
Thermal composition fluctuations and the associated crossover from the 3D Ising to the isotropic Lifshitz universality class have been studied in a three component mixture made of a critical polymer blend and the corresponding diblock copolymer. The critical exponents were found to be appreciably larger than those of…
Strong electro-optical (EO) anisotropy has been measured in (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 [(1−x)PMN–xPT] single crystalline films epitaxially grown on (100)-cut LaAlO3 substrate, through using an improved dynamic alternating-current ellipsometric null EO detection technique with high accuracy. Large quadratic EO coeff…
We report on the thermoelectric properties of two ternary tellurides with known crystal structures. Both compounds have a very low lattice thermal conductivity. Tl2SnTe5 appears to have a p-type figure of merit about the same as that of Bi2Te3, the best thermoelectric material among binary compounds. We have synthesiz…
Surface relief gratings have been optically inscribed on azopolymer films on the interior surface of an empty liquid crystal (LC) cell. Uniform LC alignment is observed in the inscribed regions when the cell is filled. Since the microgrooves are on both sides, this may provide a higher degree of order than other techn…
We applied the technique of focal-series reconstruction in high-resolution electron microscopy for a precise determination of the spacings between atomic columns at a $\ensuremath{\Sigma}3$ ${111}$ twin boundary in perovskite ${\mathrm{BaTiO}}_{3}$. We succeeded in observing a predicted expansion of the nearest Ti-Ti…
Synchrotron x-ray diffraction measurements have been made on hexagonal crystal Ti3SiC2 under pressures up to 61 GPa and at room temperature. No phase transition was observed within the pressure range studied. Both the a and c axes exhibited decreases with pressure, accompanied by a decrease in the c/a ratio to about 5…
The blue mixed-crystal title compound Na15[MoMoO462H14 (H2O)70]0.5[MoMoO457H14 · (H2O)68]0.5 · ca. 400 H2O ≡ Na15[1 a]0.5[1 b]0.5 · ca. 400 H2O 1, which crystallizes in the triclinic space group P 1 (a = 30.785(2), b = 32.958(2), c = 47.318(3) Å, α = 90.53(1), β = 89.86(1), γ = 96.85(1)°, V = 47665(6) Å3, Z = 2, Dcalc…
The electronic and phase-coherent transport properties of doped carbon nanotube junctions are studied. It is shown that there are regions of negative differential resistance in the $I\ensuremath{-}V$ characteristic of small radius metallic tubes, which are not seen for semiconducting tubes. Their origin, as discussed,…
We have performed magnetic and transport measurements on La0.7Ca0.3MnO3 polycrystalline pellets and thin films. We propose a model that reproduces very well the low-field and high-field magnetoresistance at low temperature. The decrease of the resistance at high fields is modeled by the opening of new conduction chann…
We define a correlation function that quantifies the spatial correlation of single-particle displacements in liquids and amorphous materials. We show that for an equilibrium liquid this function is related to fluctuations in a bulk dynamical variable. We evaluate this function using computer simulations of an equilibr…
Peierls-type instabilities in quarter-filled ($\bar{n}=1/2$) and half-filled ($\bar{n}=1$) quantum double-well hydrogen-bonded chain are investigated analytically in the framework of two-stage orientational-tunnelling model with additional inclusion of the interactions of protons with two different optical phonon bran…
We have induced large elastic strains in ropes of single-wall carbon nanotubes, using an atomic force microscope in lateral force mode. Freely suspended ropes were observed to deform as elastic strings with tension proportional to elongation. Ropes were elastically deformed over >10 cycles without showing signs…
We have prepared a series of model porous glasses using a recently developed molecular dynamics procedure (Gelb, L. D. and Gubbins, K. E., 1998, Langmuir, 14, 2097) that mimics the experimental processes that produce Vycor and controlled pore glasses. Using Grand Canonical Monte Carlo simulations we have measured nitr…
α-methylstyrene–methyl methacrylate emulsion copolymerizations have been investigated at various temperatures (60, 70, 85°C) on the whole composition range. The kinetic behavior has been studied, such as conversion, particle size, and the average number of radicals per particle (ñ), as well as the following characteri…
The effect of self-nucleation on the crystallization and melting behavior of isotactic polypropylene (i-PP) and low ethylene content propylene–ethylene copolymers were investigated. Isothermal crystallization kinetics were studied using the Avrami equation and Lauritzen-Hoffman nucleation theory. It was found that sel…
Monoclinic (α) and hexagonal (β) polypropylene (α- and β-PP) were stained in the vapor of a ruthenium tetroxide solution prepared in situ. The effect of staining on the fusion behavior was investigated using a DSC. A staining duration between 10 and 24 h was found suitable for obtaining a good electron contrast betwee…
The disposal of used car tires has become a major environmental problem, especially in densely populated countries that use motor vehicles as the principle means of transportation. Widespread recycling of waste tires has not taken place because it has not proven to be cost effective. Although there are obvious environ…