Materials Literature
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Dielectric and x-ray diffraction evidences are presented to show that the antiferroelectric to ferroelectric phase transition in (Pb0.90Ba0.10)ZrO3 ceramics is not reversible during the cooling cycle. It is shown that the stable antiferroelectric phase recovers from the metastable ferroelectric matrix on aging at room…
The surface compositions of a series of five polystyrene−polypyrrole (PS−PPy) composites and three reference materials (the original poly(ethylene glycol) (PEG) stabilizer, the uncoated PEG-stabilized PS latex, and PPy chloride bulk powder) were examined by X-ray photoelectron spectroscopy (XPS). The uncoated PEG-stab…
The resistivity of single-crystal pentatellurides, ${\mathrm{HfTe}}_{5}$ and ${\mathrm{ZrTe}}_{5},$ has been measured as a function of temperature and applied magnetic field. At zero magnetic field these materials exhibit a peak in their resistivity (at ${T}_{P})$ as a function of temperature that corresponds to an, a…
LiZn ferrite films of composition Li00.5−x/2Mn0.1ZnxFe2.35−x/2O4 with x=0.32 were rf sputter deposited on fused quartz substrates at ambient temperature. The as-deposited films were found by x-ray diffraction to be amorphous but magnetic, and showed large high field susceptibility. The films were studied after they we…
The problem of self-compensation of charged dopants is analyzed. Special emphasis is given to dopants in binary oxides. It is shown that one can determine the degree of self-compensation from the properties of the host material and dopant concentration alone. It is further shown that for a native p-type semiconductor,…
We report on the pressure dependence of the local segmental and normal modes of a type-A polymer (polyisoprene) using dielectric spectroscopy. We find that external pressure exerts a stronger influence on the dynamics of the segmental mode as compared to the longest normal mode which results in the crossing of the two…
The interlayer magnetoresistance of layered metals in a tilted magnetic field is calculated for two distinct models for the interlayer transport. The first model involves coherent interlayer transport, and makes use of results of semiclassical or Bloch-Boltzmann transport theory. The second model involves weakly incoh…
Organically capped zinc sulfide nanoparticles doped with different manganese concentrations were prepared under similar conditions. Only the doping concentration was varied. Photoluminescence and electron-spin-resonance (ESR) investigations show some new results. At an optimum concentration of Mn doping a maximum in t…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTA New Approach to Hyperbranched Polymers by Ring-Opening Polymerization of an AB Monomer: 4-(2-Hydroxyethyl)-ε-caprolactoneMingjun Liu, Nikolay Vladimirov, and Jean M. J. FréchetView Author Information Department of Chemistry, Unive…
We previously identified the prpBCDE operon, which encodes catabolic functions required for propionate catabolism in Salmonella typhimurium. Results from (13)C-labeling experiments have identified the route of propionate breakdown and determined the biochemical role of each Prp enzyme in this pathway. The identificati…
Nanocrystalline europium doped yttria was synthesized using a chemical vapor technique. The powder was characterized by x-ray diffraction, transmission electron microscopy, and ultraviolet spectroscopy. For the first time it was possible to obtain single phase Y2O3:Eu nanoparticles crystallized in the cubic structure…
We investigate the phase behavior of symmetric AB diblock copolymers confined into a thin film. The film boundaries are parallel, impenetrable and attract the A component of the diblock copolymer. Using a self-consistent field technique [M. W. Matsen, J. Chem. Phys. 106, 7781 (1997)], we study the ordered phases as a…
We find that solvability theory selects a set of stationary solutions of the Saffman-Taylor problem with coexistence of two \it unequal \rm fingers advancing with the same velocity but with different relative widths $λ_1$ and $λ_2$ and different tip positions. For vanishingly small dimensionless surface tension $d_0$,…
A model is presented for the development of stress during electromigration. Formally similar to a thermal stress model, it provides a method of calculating all of the components of the stress tensor and clearly couples vacancy transport and stress evolution with the boundary conditions that apply to the metal. Analyti…
Magnetoresistance measurements in the CPP geometry have been performed on single electrodeposited Co nanowires exchange biased on one side by a sputtered amorphous GdCo layer. This geometry allows the stabilization of a single domain wall in the Co wire, the thickness of which can be controlled by an external magnetic…
We have developed a pair-potential approach for the evaluation of van der Waals interaction between carbon nanotubes in bundles. Starting from a continuum model, we show that the intertube modes range from 5 ${\mathrm{cm}}^{\ensuremath{-}1}$ to 60 ${\mathrm{cm}}^{\ensuremath{-}1}.$ Using a nonorthogonal tight-binding…
We consider core electron photoemission in a localized system, where there is a charge transfer excitation. Examples are transition metal and rare earth compounds, chemisorption systems, and high-${T}_{c}$ compounds. The system is modeled by three electron levels, one core level, and two outer levels. In the initital…
In this paper we analyze the optical absorption in porous silicon. This is the first attempt to explicitly demonstrate that it is not possible to extract the band gap of low-dimensional nanostructures like porous silicon from a Tauc plot of $\sqrt{\ensuremath{\alpha}\ensuremath{\Elzxh}\ensuremath{\omega}}$ vs \ensurem…
A subazaporphyrin (SubAP), tert -butylated and crowned subphthalocyanines (tBSubPc and SubCRPc), a μ-oxo dimer of tert -butylated SubPc {(tBSubPc) 2 O}, a subnaphthalocyanine (SubNc), and monosubstituted type unsymmetrical phthalocyanine (Pc) and naphthalocyanine (Nc) analogues have been synthesized. In particular, un…
This paper reports two fundamental observations on the size-dependent optical properties of colloidal gold nanoparticles. First, faceted gold nanocrystals in the size range of 63 ± 3 nm have been found to be highly efficient for surface-enhanced Raman scattering (SERS). These nanocrystals are identified from a heterog…