Materials Literature
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Density, DC conductivity and 11B wide-line NMR investigations have been carried out for xFe2O3-(50-x)PbO-50B2O3 glasses (0<or=x<or=20 mol%). The NMR spectra indicated the formation of non-bridging oxygen ions in the borate network upon introducing Fe2O3. The DC conductivity and the activation energy for conduction cha…
New experimental results on Raman scattering from porous silicon and silicon and gallium arsenide nanocrystals are reported. In all of these systems, almost all vibrational modes become Raman active and are remarkably soft. A carrier-induced strain model is proposed to explain the optical properties of these nanocryst…
Abstract The morphology and mechanical properties of polyamide‐based blends prepared in single and corotating twin‐screw extruders were compared using transmission electron microscopy (TEM) techniques. Reactive polyamide blends with SEBS‐ g ‐MA (a maleated styrenic triblock copolymer with ethylene–butvlene midblocks),…
Low temperature annealing of insulatinglike AlPdRe icosahedral-quasicrystalline (iqc) samples has led to unexpected large changes in their transport properties, with resistivities at 0.45 K increasing from \ensuremath{\sim}1 to > 10 \ensuremath{\Omega} cm, but their electronic structure is apparently unaffected. Th…
We describe the preparation, characterization, and use of ‘‘plastic’’ infrared polarizers that consist of electrically conductive polyaniline blends with common bulk polymers such as poly(acrylonitrile), polyethylene, and poly(vinylalcohol). It is shown that uniaxially oriented blends of protonated polyaniline in, for…
We report on experimental valence and conduction electronic distributions of quasicrystalline Al-Mn-Pd alloys probed using the soft x-ray emission and absorption spectroscopy techniques. The various partial distributions are adjusted in the binding energy scale in order to investigate the electronic interactions chara…
Abstract Microwave transmission, reflection, and absorption behavior and the shielding effectiveness of electrochemically synthesized polypyrrole films with dc conductivities ranging from 0.001 to 50 S/cm are presented. Results show that the electrical conductivity of the doped polypyrrole films has a significant effe…
Molecular structures can perform diverse functions . Tailored bolaamphiphiles were used to prepare vesicles containing redox‐active centers or (chiral) binding sites for guests, as well as aggregates. In addition, monomeric and polymeric bolaamphiphiles can disrupt membranes. RNA‐based bolaamphiphiles of this type may…
We report the growth of epitaxial SrxBa1−xNb2O6 (SBN) thin films by pulsed laser deposition. The films were grown on (100) MgO substrates with thicknesses in the range 200–400 nm. Rutherford backscattering analysis showed that the films have stoichiometric composition identical to the target material. X-ray diffractio…
For 30 diamond- and zincblende-structure semiconductors, the bond length d, bond polarity alpha p , bulk modulus B, elastic shear constants (c 11 -c 12 )/2 and c 44 , bond-stretching force constant alpha , bond-bending force constant beta , internal displacement parameter zeta , effective atomic charge Z*, transfer pa…
Dynamic processes in liquid propylene glycol and two of its oligomers inside the \ensuremath{\cong} 100 \AA{} pores of controlled porous glasses have been investigated as a function of temperature by dielectric spectroscopy. We find that geometrical restriction results in retardation and broadening of the inherent $\e…
We report the observation of giant magnetoresistance near room temperature in ferromagnetic films of La1−xSrxMnOz for 0.16≤x≤0.33. For B=5 T, the maximum magnetoresistance ratio [R(0)−R(B)]/R(0) of an annealed film is 60% at 260 K for x=0.2, and 35% at 330 K for x=0.33. Annealed films have higher Curie temperature (Tc…
Abstract In der Übergangsmetallchemie gibt es eine Klasse von Komplexverbindungen, bei denen eine Temperaturerniedrigung einen Wechsel im Spinzustand des Zentralatoms vom High‐Spin‐ in den Low‐Spin‐Zustand bewirkt. Dabei ändern sich die magnetischen und optischen Eigenschaften, über die der thermische Spinübergang (au…
The elastic moduli directly reflect bonding strength and structure. Usually these factors can be only slightly modified within a given material, but in amorphous carbon films large variations of Young's modulus from less than 100 up to more than 500 GPa are found. This can be attributed mainly to the varying fraction…
In addition to the well-known properties of diamond-like-carbon (DLC) coatings, the surface tension is a new criterion to characterize this kind of thin films. To influence the surface tension of DLC coatings, their structure is modified by the incorporation of different elements like fluorine or silicon into the matr…
Electron-momentum spectroscopy [binary encounter (e,2e)] experimental results are presented for the core state of an amorphous carbon allotrope. The (e,2e) cross section has two identifiable regions. One is a narrow-energy-width core-band peak that does not disperse with momentum. At higher binding energies there is a…
A kinetic and ligand binding study on maize (Zea mays) malate synthase is presented. It is concluded from kinetic measurements that the enzyme proceeds through a ternary-complex mechanism. Michaelis constants (Km,glyoxylate and Km,acetyl-CoA) were determined to be 104 microM and 20 microM respectively. C.d. measuremen…
We report results for photoluminescence studies of an impurity-related defect system in 450 \ifmmode^\circ\else\textdegree\fi{}C annealed Czochralski-grown silicon resulting in optical emission with a wavelength near 1.7 \ensuremath{\mu}m. The photoluminescence emission is found to have a significant intensity that pe…
Medium-energy ion-scattering measurements and Monte Carlo simulations have been used to study the Al(001) surface as a function of temperature. Surface melting does not occur and the surface stays well ordered up to the bulk melting point ${\mathit{T}}_{\mathit{m}}$=933.52 K. The combination of the effective-medium po…
The electronic and the optical properties of \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ are studied by means of first-principles local-density calculations. The structural properties obtained via total-energy calculations are in good agreement with the results of Liu and Cohen [Phys. Rev. B 41, 10727 (199…