Materials Literature
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Quantum confinement effects in Ge nanocrystals in the size range 26–130 Å have been investigated both on the electronic joint density of states and Raman spectra. The high degree of crystallinity of the particles as well as the minimized interaction with the matrix allow detection of shift and broadening of the TO Ram…
Lithium ferrite nanocrystallites ranging from several nanometres to several hundreds of nanometres in size have been prepared by the polyethylene glycol gel method. These nanocrystallites were identified as pure lithium ferrite by x-ray diffraction analysis. Their magnetization and de-magnetization were measured by us…
The reduction of copper oxide thin films by a hydrogen plasma generated by an atmospheric-pressure glow (APG) discharge was investigated. The copper oxide films were prepared by heating the sputtered copper films to C in the air (heat-formed copper oxide) or by sputtering (sputtered copper oxide). Both films were comp…
We report a new photophysical phenomenon in which 1.06 \ensuremath{\mu}m pulses from a Q-switched Nd:YAG laser induce crystallization in supersaturated solutions of urea in water. Because the solutions are transparent at the incident wavelength, a photochemical mechanism is unlikely. The needle-shaped crystals that in…
We report the degree to which the resonances associated with metal island films can be used to enhance the sensitivity of very thin semiconductor photodetectors. The island films can couple incident light into the waveguide modes of the detector, resulting in increased absorption. To characterize the coupling, silver-…
The birefringence of planar 8OCB samples has been measured as a function of temperature at thicknesses decreasing from 7.2 to 2.6 μm. The first curve (7.2 μm) is perfectly superimposable to the result of conoscopic measurements done with a 100 μm homeotropic uniaxial sample, from a minimum of 0.08 close to the isotrop…
Different emulsion polymerization processes allowed variation in the microstructure of composite natural rubber (NR)-based latex particles. A prevulcanized and a not-crosslinked natural rubber latex were coated with a shell of crosslinked poly(methyl methacrylate) (PMMA) or polystyrene (PS). The bipolar redox initiati…
We have prepared nanosized hairy grains by grafting long polydimethylsiloxane chains onto silica particles of radius ≈ 15 nm. The synthesis method allows the particles to keep in truly stable suspension at any stage of their preparation. In dilute suspension, these hairy grains behave as repulsive soft spheres. Above…
Blends composed of poly(ether imide) and poly(ethylene terephthalate) were obtained both by kneading followed by compression molding and by direct injection molding. Both procedures gave rise, probably at all compositions, to biphasic structures with similar homogeneity that showed wide single Tg peaks by dynamic-mech…
The theoretical relationship between dislocation density ρ and applied stress σ of the type σ ∝ ρ 0.5 is an essential part of many microphysical models for dislocation dynamics and creep. Thus, application of these microphysical models requires demonstration of this relation. In an attempt to determine the relation be…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEley−Rideal Surface Chemistry: Direct Reactivity of Gas Phase Atomic Hydrogen with Adsorbed SpeciesW. Henry WeinbergView Author Information Department of Chemical Engineering, University of California, Santa Barbara, California 93106 Cite this: Acc. Chem. Res. 1996, 29, 10,…
It was demonstrated that the mechanical stress-induced βα-transformation in isotactic polypropylene (iPP) is associated with considerable toughness enhancement. This toughness improvement depends on the test conditions (loading frequency). The toughness of β-iPP was superior to the α-iPP by 13% under static (character…
Measurements of the coexistence curves for phase-separated polymer solutions of polymethylmethacrylate in 3-octanone (PMMA/3-OCT) for six different molecular weights of PMMA have been carried out. We have tested the scaling behavior of the order parameter Δφ (the difference between polymer volume fractions in the two…
Ab initio electron propagator calculations on tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE) produce accurate predictions of vertical ionization energies and electron affinities. Plots of Feynman–Dyson amplitudes associated with each ionization process represent how the electron distribution changes fro…
The noise in the depth profiles of secondary ion mass spectrometry (SIMS) is studied using different samples under various experimental conditions. Despite the noise contributions from various parts of the dynamic SIMS process, its overall character agrees very well with the Poissonian rather than the Gaussian distrib…
Polarized neutron diffuse scattering studies made above and below the re-ordering temperature on an crystal have revealed a random atomic arrangement of Mn and Fe atoms. The magnetic disturbance produced by Mn atoms is confined to the substituted sites. There appears to be greater change in the moment difference betwe…
A soap film (made of two air/water interfaces covered by surfactant) may turn into a so-called Newton black film (NBF) which essentially consists in a surfactant bilayer. Oil-in-water emulsion droplets covered with surfactant (oil/water interfaces) may become adhesive in similar conditions. We show by analyzing the ne…
The structure factor of a poly(ethylene-propylene)-poly(dimethylsiloxane) diblock copolymer has been measured by small-angle neutron scattering as a function of temperature and pressure. The conformational compressibility exhibits a pronounced maximum at the order-disorder phase transition. The phase boundary shows an…
Tunneling spectroscopy studies on oxidized and bare surfaces of icosahedral i-AlPdRe, i-AlCuFe, and approximant $\ensuremath{\alpha}$-AlMnSi phases reveal specific features of the density of states (DOS) close to the Fermi level as compared to the crystalline nonapproximant $\ensuremath{\omega}$-AlCuFe phase. The Ferm…
We report the first observation of the vibrational Raman spectrum of hydrogen molecules ${\mathrm{H}}_{2}$ in crystalline silicon treated with hydrogen atoms at 400 \ifmmode^\circ\else\textdegree\fi{}C. The Raman spectrum of ${\mathrm{H}}_{2}$ in silicon observed at room temperature exhibits a frequency shift of aroun…