Materials Literature
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Monte-Carlo simulation technique has been used to investigate the effect of temperature and adsorbed gases on the composition profile of unsupported Pt-Rh nanocatalysts. For a 2406 atom fcc cubo-octahedral Pt$_{\rm{}50}$Rh$_{\rm{}50}$ nanocatalyst the shell-wise composition for all the eight shells has been simulated.…
We report Raman scattering and visible to near-infrared absorption spectra of solid hydrogen under static pressure up to 285 GPa at 85-140 K. We obtain pressure dependences of vibron and phonon modes in agreement with previously determined to lower pressures. The results indicate the stability of the ordered molecular…
We present the results of a study of the specific heat on a single crystal of ${\mathrm{Pr}}_{0.63}{\mathrm{Ca}}_{0.37}{\mathrm{MnO}}_{3}$ performed over a temperature range 3--300 K in the presence of 0 and 8 T magnetic fields. An estimate of the entropy and latent heat in a magnetic field at the first-order charge-o…
Dark soliton excitations are shown to exist in single wall carbon nanotubes (SWCNTs). At first, the nonlinear effective interatomic potential and the difference equation for longitudinal lattice displacement are obtained for the SWCNTs by expanding Brenner's many-body potential in a Taylor series up to fourth-order te…
We discuss numerical and theoretical results for models of magnetization switching in nanoparticles and ultrathin films. The models and computational methods include kinetic Ising and classical Heisenberg models of highly anisotropic magnets which are simulated by dynamic Monte Carlo methods, and micromagnetics models…
The effect of thermal fluctuations on a thin film magnetoresistive element has been calculated. The technique involves adding to the basic spin dynamics a general form of interaction with a thermal bath. For a general anisotropic magnetic system the resulting equation can be written as a Langevin equation for a harmon…
Methanol oxidation on a supported Pt fuel cell catalyst was investigated by on-line differential electrochemical mass spectrometry (DEMS) at continuous electrolyte flow and defined catalyst utilization, employing a thin-film electrode setup and a thin-layer flow-through cell. The active surface of the Pt/Vulcan (E-TEK…
Despite the importance of (11)B nuclear magnetic resonance (NMR) in structural studies of borate glasses, no clear means of correlating NMR parameters with the number of nonbridging oxygens on three-coordinate boron has been demonstrated. In this work, a series of anhydrous, polycrystalline, binary borates has been ex…
Subsequent to work by Boustani on B 12 clusters in free space, a study is made of B 12 clusters embedded in graphitic fragments with use of Hartree−Fock methodology. To gain insight about defect embedding for an extended graphite layer, clusters of varying sizes up to 336 C atoms have been studied. Bonding density map…
Abstract A ternary system polypropylene (PP)/calcium carbonate (CaCO 3 )/high molar mass polysiloxane has been investigated with respect to its processing, crystallization, and dynamic mechanical properties. The filling level of PP varied from 2.5 vol % to 6.5 vol % CaCO 3 and 0.6 vol % to 2.5 vol % polysiloxane, and…
We present a systematic trend study of the symmetric tilt grain boundaries about the $〈110〉$ axis in molybdenum. Our results show that multiple structural phases, some incorporating vacancies, compete for the boundary ground state. We find that at low external stress vacancies prefer to bind to the boundaries in high…
Mesoporous silicon doped with 3.0 x 10(19) B atoms cm-3 (p(+)-type) is an insulating material which dramatically increases its electrical conductivity when exposed to traces of gaseous NO2; nitrogen dioxide chemisorption at the surface generates carriers, the population of which is readily evaluated through the intens…
We present a simplified model for the colossal magnetoresistance in doped manganites by exactly solving a double-exchange model (with Ising-like local spins) and quenched binary disorder within dynamical mean field theory. We examine the magnetic properties and the electrical and thermal transport. Our solution illust…
The reactions of [M(PPh(3))(2)[S(2)C=C[C(O)Me](2)]] [M = Pd (1a), Pt (1b)] with AgClO(4) and PPh(3) or with [Au(PPh(3))(OCMe(2))]ClO(4) afford heterodinuclear [[M(PPh(3))(2)][M'(PPh(3))][S(2)C=C[C(O)Me](2)]]ClO(4) [M = Pd, M' = Ag (2a), M = Pt, M' = Ag (2b), Au (4)] or trinuclear [[M(PPh(3))(2)][M'(PPh(3))](2)[S(2)C=C…
Abstract The influence of microscale fillers on ethylene–propylene rubbers (EPR) was examined with respect to their vibrational damping capacity and viscoelastic properties. The vibrational damping and dynamic mechanical properties of reinforced EPR were studied in systematic and comparative ways that reinforced the e…
The cyclization kinetics of a poly(ethylene oxide) (PEO) chain ( M n = 3280; M w / M n = 1.05) labeled at both ends with pyrene was studied in toluene at several temperatures. Above 30 °C, the kinetics of pyrene excimer formation is well described by a two-state model. Below this temperature, a new excited species app…
The influence of the intermolecular potential on predicted growth morphologies is investigated. We compare the morphologies calculated with the attachment energy model for ε-caprolactam ( C 2/ c ), β-succinic acid ( P 2 1 / c ), hexamethylene tetramine ( I 4̄3 m ), pentaerythritol ( I 4̄), and urea ( P 4̄2 1 m ). Five…
Ethyl isocyanate has been introduced on prereduced and preoxidised Ag(2%)/Al2O3 catalysts and on Ag(2%)/SiO2 for comparison at 573 K. Its decomposition on preoxidised silica catalyst gives IR bands at 2294 and 2204 cm−1 whereas on prereduced catalyst vibrations at 2294 and 2243 cm−1 are observed. The 2294 cm−1 feature…
The dielectric properties of structurally monodomain, oxygen-isotope-exchanged ${\mathrm{SrTiO}}_{3}$ samples, $\mathrm{SrTi}{(}^{16}{\mathrm{O}}_{1\ensuremath{-}x}{}^{18}{\mathrm{O}}_{x}{)}_{3},$ were investigated. It was found that ferroelectricity is intrinsic to $\mathrm{SrTi}{(}^{16}{\mathrm{O}}_{1\ensuremath{-}x…
Metal nanoparticles play an important role in chemical vapor deposition (CVD) synthesis of carbon nanotubes because nanoparticles not only catalyze the nanotube growth but also determine the structural characteristics of the nanotubes. We report on the synthesis of single-wall carbon nanotubes (SWNTs) on the basis of…