Materials Literature
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A formal comparison between a rigorous implementation of a Heisenberg Hamiltonian model in a VB space with the McConnell-I model shows that the validity of the McConnell model rests upon a heuristic one-to-one correspondence between spin density products in the latter with the difference of the spin exchange density m…
Local structure analysis of Al-containing magnesium silicate perovskite has been carried out with X-ray absorption spectra recorded at the Mg, Al, and Si K-edges using the SA32 beam-line of SuperAco (Orsay, France). The Al-XAFS spectrum of (MgSi) 0.85 Al 0.3 O 3 perovskite (synthesized in a multi-anvil apparatus) cann…
The structure and dynamics of structure formation have been studied in model triarm star block copolymers composed of two crystallizable blocks (poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL)) and one amorphous block (polystyrene (PS)). Crystallization starts from the homogeneous phase. For the structure in…
Self-standing films of surfactant mesostructured materials have been prepared with vinyltrimethoxysilane (VTMOS) as a silica source. The transparent films, obtained by the co-condensation of VTMOS and tetramethoxysilane, can easily be converted to porous silica films by calcination. The authors reveal the porous struc…
The properties of a ferroelectric material deposed as a thin film on a substrate depend on the method of preparation and on the nature of the substrate used. The present work reports fine characterization by x-ray diffraction of structural modifications (cell parameters, preferential orientations) and microstructural…
Large scale quantities of quasi-aligned carbon nanotube bundles have been synthesized by catalytic decomposition of acetylene over well dispersed metal particles (cobalt and vanadium) embedded in commercially available zeolite at 700°C. Scanning electron microscopy analysis revealed the homogenous nature of the sample…
Grain boundaries in oxide materials such as electroceramics, ferroelectrics, and high-${T}_{c}$ superconductors are known to dominate their overall bulk properties. The critical first step in a fundamental understanding of how they control the properties of the material is a determination of the atomic structure of th…
It is shown that the anharmonicity of vibrations leads to the quasielastic scattering in glasses and supercooled liquids. The vibrational self-energy term which arises due to the anharmonic interaction provides the one-phonon quasielastic response. Estimations show that in the glass transition region the contribution…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTWell-Defined Triblock Hybrid Dendrimers Based on Lengthy Oligothiophene Cores and Poly(benzyl ether) DendronsPatrick R. L. Malenfant, Lambertus Groenendaal, and Jean M. J. FréchetView Author Information Department of Chemistry, University of California Berkeley, Califo…
XPS spectra acquired on anodized niobium during a thermal treatment from 300 to 1223 K are reported. The anodization process consists of growing a layer of oxide of known thickness on the metal surface; the sample is kept in a solution of ammonia inside an electrochemical cell and a d.d.p. is applied to the electrodes…
An analysis is made of electrostatic systems whose field is formed by two superposed two-dimensional fields with a common plane of symmetry (midplane). It is assumed that these fields overlap in the region where a charged particle beam propagates. The main property of these systems is that they conserve ideally (witho…
Abstract An ethylene‐propylene‐diene rubber (EPDM), containing 5 wt% 5‐ethylidene‐2‐norbornene, was functionalized with maleic anhydride through the Alder Ene reaction at temperatures above 200°C in a co‐rotating twin screw extruder. Characterization of the maleated product included FT‐IR, 1 H and 13 C NMR, and GPC. T…
Journal Article Measurement of Performances of Aerosol Type Radioactive Contamination Monitors Get access L. Grivaud, L. Grivaud Search for other works by this author on: Oxford Academic PubMed Google Scholar S. Fauvel, S. Fauvel Search for other works by this author on: Oxford Academic PubMed Google Scholar M. Chemto…
Abstract Computer simulation techniques have been used to investigate defect formation and the diffusion of Ca and Mg in diopside. It was found that isolated, non-interacting CaO and MgO Schottky defects had the lowest formation energies (3.66 and 3.97 eV respectively); oxygen Frenkel defects are the most favourable o…
X-ray photoemission measurements of CuCO3 are presented.
Thermal conductivity (at 5 to 300 K), dielectric (at 5 to 250 K) and sound velocity (at 5 to 150 K) measurements have been performed for the first time on ceramic samples of Na0.5Bi0.5TiO3. The data revealed a nearly temperature-independent plateau in thermal conductivity λ(T) at about 7 to 30 K and ≈︂0.2 W/mK. This p…
A theoretical study of the magnetic susceptibility of multilayered carbon nanotubes in fields both parallel, H ∥, and perpendicular, H ⊥, to the tube axis has been carried out disregarding electron-electron interaction. The temperature dependences of the magnetic susceptibility obtained exhibit a nontrivial form for H…
We propose simple configurations to measure the thermoelectric power and the four-probe resistivity simultaneously for different types of samples.
An Inconel 718 based alloy containing only trace amounts of C, S, and P was subjected to thermal cycling in a Gleeble 1500 system to induce microstructural features which are produced in the heat affected zone (HAZ) during welding. In the thermally cycled material many grain boundaries were observed to liquate; howeve…
Nano-MgO particles have been introduced into silver-sheathed tapes fabricated by the rod-in-tube process. It is found that the transport properties of the nano-MgO particle doped sample are noticeably improved compared with those of the undoped sample. The irreversibility line of the MgO-doped sample shifts to higher…