Materials Literature
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We study the equilibrium and kinetic properties of a model for polydisperse mixture adsorption. The system consists of a bulk phase of hard disks with a given size distribution and overall concentration that adsorb and desorb on a continuous planar surface. The disks adsorb at a rate proportional to their bulk concent…
The graft copolymerization of butyl acrylate onto poly(vinyl alcohol) with ceric ammonium nitrate as redox initiator in a aqueous medium has been investigated. The formation of graft copolymer was confirmed by means of IR, scanning electron microscopy (SEM), and wide-angle X-ray diffraction (WAXD). The percentage of m…
The recycled polyolefinic product from discarded standard car bumpers collected from Rio de Janeiro suburb shops was characterized by mechanical and wide-angle X-ray scattering (WAXS) methods. We found that the recycled plastic mixture is composed mainly of polypropylene (PP), containing ethylene-propylene-diene (EPDM…
Accelerated flex fatigue testing was carried out on nylon 6.6 tire cords, under various applied tensions (stress), at standard atmospheric conditions of 65% relative humidity and 21°C. Fatigue lifetime was measured and scanning electron microscope used to investigate the nature of failure. The study concluded that the…
Ab initio calculations on a linear –OTiOTiO– chain embedded in an envelope of (SiO4) tetrahedra, mimicking the structure of Na2TiSi5O13 molecular sieve (ETS-10), confirm that the peculiar optical properties of the solid are associated with the presence of –OTiOTiO– linear chains behaving as quantum wires. The optical…
Aminoalkyl phenol derivatives were prepared and tested for electrooxidation in alkaline hydroalcoholic electrolytes. We estimated the relative insulating character of thin (<0.3 μm) organic coatings on several metal electrodes (Fe, Cu, and Ni), through both voltammetric and potentiostatic runs. Unsaturated allyl and b…
Low-temperature synthesis of spinels Mg x Co 1 - x Co 2 O 4 ( x = 0.0−0.9) has been investigated with two important synthetic parameters and XRD/FTIR/DSC/BET/ICP/CHN methods. It is found that with an increase in hydrothermal treatment temperature, precursor compounds change from the hydrotalcite-like to brucite-like a…
The two-band Hubbard model with the density of states obtained from the band calculation is applied for FeSi, which is suggested to be a Kondo insulator or a correlated band insulator. Using this model, the correlation effects on FeSi are investigated in terms of the self-consistent second-order perturbation theory co…
Compositionally step-varied (Pb, Ca)TiO3 thin films were prepared on platinum-coated silicon substrates by a monoethanolamine-modified sol-gel technique. The dielectric constant and dissipation factor were found to be 342 and 0.019, respectively, for thin films of 0.6μm in thickness annealed at 550 °C for 60 min. The…
The oxygen-deficiency-activated charge ordering (CO) transition has been observed in C-oriented La2/3Sr1/3MnO3−δ thin films prepared by pulsed laser deposition on LaAlO3 substrates. A rapid growth of the sample resistivity at temperatures below TC is observed, while significant thermal hysteresis and electrical field…
Intra-valence band photocurrent investigations of self-assembled Ge dots in Si are reported. Boron-doped Ge dots of about 70 nm diameter and 6.5 nm height are deposited by molecular beam epitaxy in the Stranski–Krastanov growth mode within the intrinsic region of a p+-i-p+ Si structure. For a broad excitation waveleng…
An icosahedral (I) quasicrystalline phase with a grain size below 40 nm was formed as a metastable phase in crystallization of the bulk glassy Zr65Al7.5Cu17.5−xNi10Mx (M=Ag, Pd, Au, or Pt; x=5 and 10 at %) alloys. The volume fraction (Vf) of the I phase is about 85% for the 5% M alloy and nearly 100% for the 10% M all…
Rapidly quenched Sm(CobalCu0.08Fe0.22Zr0.02)8.5 (Cu-/Fe-rich) and Sm(CobalCu0.05Fe0.10Zr0.03)8.5 (Cu-/Fe-poor) ribbons have been prepared by means of the melt-spinning technique. By applying an appropriate annealing procedure a microstructure similar to that of sintered magnets can be obtained. The energy dispersive x…
Using Brillouin scattering, we have determined the complete set of elastic constants of the technologically important β-Si3N4. Availability of single crystals has allowed us to measure all five independent cij, which (in units of GPa) are: c11=433(3), c33=574(3), c13=127(5), c44=108(2), c66=119(4), and c12=c11−2c66=19…
In multilevel interconnects, current crowding occurs whenever the current changes direction, such as when passing through a via. We propose that in current crowding, the current-density gradient can exert a driving force strong enough to cause excess vacancies (point defects) to migrate from high to low current-densit…
Large-scale molecular dynamic simulations of the axial deformations in single-walled carbon nanotubes have been performed using an O(N) tight-binding method. Our simulations indicate that under large strain, 0 K stress is remarkably sensitive to helicity, and that a zigzag nanotube and an armchair nanotube are the sti…
Indices of refraction for MgxZn1−xO epitaxial films grown by pulsed-laser deposition on sapphire substrates with x up to 0.36 were determined in the range of wavelength 457–968 nm by analysis of optical transmission spectra and prism-coupled waveguide measurements. The dispersion follows the first-order Sellmeier disp…
An anomalous large level shift is newly found to correct the one-electron spectrum of a closed-shell carbon nanocluster, for example, the spectrum which was described within the model of a thin quantum well rolled into a sphere. As a result of the interaction with zero-point oscillations of the confined modes of the e…
We present a novel computational method to simulate accurately a wide range of interfacial patterns whose growth is limited by a large-scale diffusion field. To illustrate the computational power of this method, we demonstrate that it can be used to simulate three-dimensional dendritic growth in a previously unreachab…
First-principles calculations of the inelastic lifetime of low-energy electrons in Al, Mg, Be, and Cu are reported. Quasiparticle damping rates are evaluated from the knowledge of the electron self-energy, which we compute within the GW approximation of many-body theory. Inelastic lifetimes are then obtained along var…