Materials Literature
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First-principles calculations on the geometric and electronic structures of undoped and doped polypyrrole chains indicate the appearance upon high doping of bipolaron states in the gap. A picture of the band-structure evolution upon doping is presented, showing the presence of bipolaron bands in the gap for experiment…
We have investigated the mechanism and driving force of the CO-induced phase transition of the Pt(100) surface. In a preceding paper, we have concentrated on the mechanism by which CO removes the surface reconstruction. As discussed, the clean reconstructed (hex) surface of Pt(100) is more stable than the unreconstruc…
Molecular dynamics has been used to study the dependence of homogeneous nucleation of the crystal on the rate with which the liquid is quenched, the initial state of the liquid and on the depth of the quench. A total of 54 simulations of quenching for a liquid rubidium system were performed and the dependence on these…
We present the results of a theoretical study of the surface electronic structure of the ideal (110), (001), and (100) faces of tin dioxide, a semiconductor crystallizing with the bulk rutile structure. The surface electronic structure is determined using a scattering-theoretic method in which the bulk electronic stru…
Electrodynamic calculations of the electric field on the surface of Ag prolate spheroids indicate that, as the size increases, the field enhancement decreases rapidly and the resonance shifts to longer wavelengths, the resonance linewidth broadens, and a new set of higher-order resonances appears. The calculated surfa…
The effect of adding 0.05 to 16.2 mol.% CeO 2 on the dielectric properties and loss tangent of sintered BaTiO 3 was investigated at different temperatures. The permittivity increased with CeO 2 additions up to 0.5 mol%, then decreased with increasing concentrations. In the samples doped with 5.6 and 16.2 mol.% CeO 2 t…
Proton mobility has been established in solid hydrazine sulphate through coulometric, conductivity, IR, DSC and TGA studies. The electrical conductivity has been measured on pressed pellets in the frequency range from 100 Hz to 100 kHz in the temperature range 300-500K. The frequency dependence of the conductivity has…
A detailed procedure leading to the evaluation of the explicit anharmonic contributions to the phonon frequency shift and the linewidth to the lowest order is described for a molecular crystal. An application is then made to obtain numerical results for phonon frequency shifts and the linewidths in deuterated naphthal…
Elastomer-modified epoxy resins have grown in usage in the past 15 years in several application areas connected with structural adhesives, composites, civil engineering/construction, electrical laminates/encapsulants and corrosion resistance. Some of this increased attention has come about through utility of telecheli…
Novel elastomeric polysiloxane modifiers for epoxy networks have been synthesized and characterized. In addition, curing studies of conventional epoxy resins incorporating these oligomers have been conducted. Structures were prepared having either epoxide, primary amine and/or secondary amine endgroups. The polymeriza…
A correlated study of the structural, optical, magnetic, and transport properties of polyacetylene, doped with iodine to nearly the metallic doping levels, shows that essentially all charges go into solitonlike states. The measurements are in quantitative agreement with charge transport via variable-range hopping amon…
Abstract The nature of the liquid crystal phases formed by different compounds and the thermal and other physical characteristics of these phases are strongly affected by the stereochemistry and structure of the molecules. Precise structure-property correlations of an embracing nature cannot yet be quantified, but eve…
Abstract Liquid crystals of disc-like molecules fall into two distinct structural types, the columnar and the nematic. The columnar phase in its simplest form consists of discs stacked aperiodically in columns, the different columns constituting a two-dimensional array, whereas the nematic phase is an orientationally…
Abstract A saturated triblock copolymer, poly(styrene‐block‐ethylene‐co‐butylene‐block‐styrene) was chemically crosslinked using trimethylol propane trimethacrylate, TMPTM, and subjected to electron beam radiation. The gel percent, Gehman ten second modulus, and stress relaxation were measured to characterize the mate…
The ν3 band of UF6 isolated in solid xenon is shown to consist of a single sharp spectral feature.
Abstract In Anlagen der Nachrichtentechnik und Elektronik treten Überspannungen auf, die zur Vermeidung von Personen‐ und Sachschäden auf ungefährliche Werte begrenzt werden müssen. Bauelemente zur Spannungsbegrenzung sind Edelgasüberspannungsableiter, die in der Regel mit radioaktiven Materialien präpariert sind. Dur…
The oxidation-reduction properties and the phase relations of mixed oxides in the system La-U-O were examined by means of thermogravimetry and X-ray diffraction method. The O/M ratios of the mixed oxides LayU1-y O2±x, prepared at 1,650°C in vacuo by the reaction of La2O3 and UO2, were expressed as 2–0.5 y except 0.2≤y…
Abstract We have measured the thermal conductivity, λ, of n‐undecane, using the transient hot‐wire technique. At low pressures, n‐undecane has a plastic crystal phase α H . The increase in λ, going from the liquid to phase α H , was 35%. For a liquid → plastic crystal transition, this is a high value. It reflects that…
Abstract The effective Debye temperature θ eff for directions normal to the (110) Ni face and with an angle of about 54° to the normal is measured by LEED for different azimuths, for electron energies of 70 to 100 and 130 to 160 eV, respectively, and for the incidence angle of a primary beam of about 60°. Under such c…
Abstract Na 2 HPO 4 kristallisiert monoklin in der Raumgruppe P2 1 /mC mit: a = 545,1(1); b = 684,7(2); c = 547,3(1) pm; β = 116,34(1)°; Z = 2. Die Struktur läßt sich von einer angenähert hexagonal dichten Anionenpackung ableiten, mit Na + in den Oktaeder‐ bzw. der Hälfte der Tetraederlücken. Es liegt Fehlordnung im…