Materials Literature
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Raman microscopy is used to study the evolution of vibrational modes of vanadium dioxide single crystals and thin films in the vicinity of the phase transition. The results support the electron correlation model of phase transformation.
We demonstrate that multiwalled BxCyNz nanotubes can be efficiently converted to BN multiwalled nanotubes via an oxidation treatment. The microstructure and composition of the precursors and final products have been characterized by high-resolution transmission electron microscopy, electron energy-loss spectroscopy, a…
Ultralow dielectric constants have been achieved for thin porous films of high-Tg polymers. Rapid solid-state polymer expansion applying supercritical carbon dioxide was used to create nanosized cavities in thin films of aromatic polyimides (see Figure). Foamed films with spherical voids less than 10 nm in size as wel…
Sr 4 Al 14 O 25 : Eu , Dy material with an extraordinarily long afterglow was synthesized via a traditional ceramic processing. Such a long afterglow observed can last over 20 h at recognizable intensity level (0.32 mcd/m2), which is attributed to energy exchange between the traps and emission states resulting from Dy…
Flat silver nanocrystals have been synthesized by using a soft chemical procedure that involves mixing two reverse micellar solutions. The resulting “nanodisks” display highly anisotropic optical properties attributed to their shape anisotropy. A dark-field TEM image of such a nanodisk, illustrating its single crystal…
A series of titanate-based layered perovskites having large values of the spontaneous polarization ${P}_{s}$ were developed for their applcations to nonvolatile ferroelectric random access memories. Among these, the Nd-modified bismuth titanate [${\mathrm{B}\mathrm{i}}_{4\ensuremath{-}x}{\mathrm{N}\mathrm{d}}_{x}{\mat…
We investigate the p-type doping difficulty in ZnO by first-principles total-energy calculations. The dopants being considered are group-I elements Li, Na, and K and group-V elements N, P, and As. We find that substitutional group-I elements are shallow acceptors, while substitutional group-V elements such as P and As…
The article gives an overview of the XANES technique contribution to the analysis of multicomponent catalysts. The theoretical basis of the technique, the interpretation of the energy position and intensity of XANES features, and the numerical methods developed to interpret XANES data on catalytic systems are describe…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTChemical Modification of Chitosan. 13. 1 Synthesis of Organosoluble, Palladium Adsorbable, and Biodegradable Chitosan Derivatives toward the Chemical Plating on Plastics†Hitoshi Sashiwa, Norioki Kawasaki, Atsuyoshi Nakayama, Einosuke Muraki, Noboru Yamamoto, Hong Zhu, Hiroshi N…
Long-lived radionuclides such as I 129 , Cs 135 and minor actinides can be incorporated in crystalline structures of several specific materials with high chemical durability. Apatites, zirconolite, monazites, thorium phosphate-diphosphate and hollandite are being studied at the CEA and among a scientific research grou…
In this paper we present a thermodynamic model for the adsorption of charged colloidal particles to air−water and oil−water interfaces from water-based suspensions and derive the equations for the respective particle adsorption isotherms. The effects of electrolyte concentration, surface charge density of both the par…
High density arrays of chromium (Cr) and layered gold/chromium (Au/Cr) nanodots and nanoholes in metal films were fabricated by evaporation onto nanoporous templates produced by the self-assembly of poly(styrene- b -methyl methacrylate) (P(S- b -MMA)) diblock copolymers. The cylindrical microdomains of the asymmetric…
With femtosecond resolution, using fluorescence up-conversion and transient absorption, we have carried out measurements on free base tetraphenylporphyrin (H 2 TPP) in benzene solution, pumping with ∼1300 cm -1 of excess vibrational energy in each of the Soret, Q y, and Q x bands, and also pumping the lowest vibration…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemical Vapor Deposition Methods for the Controlled Preparation of Supported Catalytic MaterialsPhilippe Serp, Philippe Kalck, and Roselyne FeurerView Author Information Laboratoire de Catalyse Chimie Fine et Polymères, Ecole Nationale Supérieure d'Ingénieurs en Arts Chimiq…
Femtosecond spectroscopic studies of zinc tetraphenylporphyrin (ZnTPP) in benzene and dichloromethane are reported, combining both fluorescence up-conversion and transient absorption measurements. The purpose is to investigate the initial electronic and vibrational relaxation of the S 1 and S 2 excited states, in a sy…
We propose coating spherical particles or droplets with anisotropic nanosized objects to allow micron-scale colloids to link or functionalize with a 4-fold valence, similar to the sp 3 hybridized chemical bonds associated with, e.g., carbon, silicon, and germanium. Candidates for such coatings include triblock copolym…
The adsorption of Ar on open-ended single-walled carbon nanotube bundles was studied. The amount of argon, which corresponds to the first coverage adsorbed on open-ended carbon nanotube bundles, was about 3 mmol/g. The isosteric heat of adsorption was obtained from the isothermal adsorption measurement in the low cove…
We investigated the coalescence of ultrathin carbon nanotubes (UTCNTs) using the tight-binding molecular dynamics simulation technique. We have found that two UTCNTs having the same or different chirality can coalesce without initially introducing atomic defects to enhance the reaction. The chiral index of the coalesc…
Ein Tetramer aus Dimeren: Ein sehr stabiles, kastenförmiges, cyclisches Tetramer (siehe Bild) wurde aus meso-Pyridyl-substituierten meso-meso-verknüpften Zink(II)-diporphyrinen erhalten, wobei die Porphyrineinheiten streng senkrecht zueinander orientiert sind.
This paper describes the onset of a new approach for the prediction of the nucleation rates of polymorphs crystallized from solution. The first step in the development of the new method is to come to an accurate prediction of the interfacial energy between the nucleus and solution, one of the key factors in the nuclea…