Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Noncentrosymmetric materials are of special interest in materials chemistry owing to their technologically important properties, such as ferroelectricity and second-order nonlinear optical behavior. Over 500 noncentrosymmetric oxides have been compiled and categorized by symmetry-dependent property and crystal class.…
We discuss the ground state and some excited states of the half-filled Hubbard model defined on an open chain with L sites, where only one of the boundary sites has a different value of chemical potential. We consider the case when the boundary site has a negative chemical potential -p and the Hubbard coupling U is po…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTAn Organic Catalytic System for Dehydrogenative OxidationToshikazu Hirao and Shinya FukuharaView Author Information Department of Applied Chemistry, Faculty of Engineering, Osaka University, Yamada-oka, Suita, Osaka 565-0871, Japan Cite this: J. Org. Chem. 1998, 63, 21, 7534–75…
It has been experimentally established in numerous cases that precipitation of monodispersed colloids from homogeneous solutions is a complex process. Specifically, it was found that in many systems nuclei, produced rapidly in a supersaturated solution, grow to nanosize primary particles (singlets), which then coagula…
We follow the structural transformation in solid C$_{70}$ from the high temperature hcp to a low temperature monoclinic phase using x-ray diffraction studies at controlled cooling-rates from 0.0033 to 0.42 K/min. Rapid cooling of the sample gives the signature of a two-step transformation which disappears when the sys…
The band gap of alkali halides, alkaline-earth oxides, Al2O3 and SiO2 crystals has been calculated using the Perturbed-Ion model supplemented with some assumptions for the treatment of excited states. The gap is calculated in several ways: as a difference between one-electron energy eigenvalues and as a difference bet…
Colloidal chemistry techniques were used to synthesize ZnO particles in the nanometer size regime. The particle aging kinetics were determined by monitoring the optical band edge absorption and using the effective mass model to approximate the particle size as a function of time. We show that the growth kinetics of th…
Gold clusters ranging in diameter from 1 to 6 nanometers have been prepared on single crystalline surfaces of titania in ultrahigh vacuum to investigate the unusual size dependence of the low-temperature catalytic oxidation of carbon monoxide. Scanning tunneling microscopy/spectroscopy (STM/STS) and elevated pressure…
Stannanes R 3 SnH (R = n-Bu, Ph) reacted with Co III (OEP)CH 3 or Co II (OEP) to afford Co III (OEP)SnR 3 and CH 4 or H 2, respectively. Co III (OEP)SnR 3 was more efficiently prepared by reaction of Co I (OEP) - with R 3 SnCl. Co III (OEP)SnPh 3, C 54 H 59 CoN 4 Sn, crystallized in the triclinic space group P 1̄ ( Z…
Director configurations in nematic Liquid Crystals can be determined by minimizing their elastic free-energy density, on the basis of elastic constants and of specific boundary conditions; in some published cases, this has been obtained by numerical procedures where the elastic free-energy density plays the same role…
The relationship between the growth rate of the hydroxyapatite (0001) face and bulk supersaturation of a simulated body fluid was measured by real-time Moire phase shift interferometry. It was found that the (0001) face grew in the multiple two-dimensional nucleation mode, from surface observation by atomic force micr…
Cathodic reduction of a mixed metal nitrate solution containing La 3+ and Mn 2+ ions leads to the deposition of an X-ray amorphous mixed hydroxide coating, which on heat treatment (950 °C, 2 h) yields an adherent coating of LaMnO 3 . This method can be adapted as a simple alternative to such conventional methods of fa…
The likely mechanism which allows the required migration of functional groups for solid-state polymerization (SSP) of polyamides and polyesters is shown to be interchange reactions. This “chemical diffusion” of functionality has exactly the same mathematical form as that of classical diffusion of small molecules. The…
Molecular weight driven competitive adsorption of PEO [poly(ethylene oxide)] from aqueous solutions on silica was studied by employing total internal reflectance fluorescence (TIRF) and near-Brewster angle reflectivity. Coumarin tags on PEO chain ends facilitated the distinction between two competing populations diffe…
A method for producing diffractive optical elements (DOE's) for multiple wavelengths without chromatic aberration is described. These DOE's can be designed for any distinct wavelength. The DOE's are produced from two different optical materials, taking advantage of their different refractive indices and dispersions.
The structure and dynamics of the “strong” glass of poly( n -decyl methacrylate) (PnDMA) have been studied, respectively, with X-ray diffraction and dielectric spectroscopy, dynamic light scattering, and rheology at temperatures below and above the glass transition temperature T g ∼ 215 K. We find three dielectrically…
An overview is presented of size-selective photoetching experiments on nanocrystalline semiconductor particles. Four different compounds (CdS, ZnS, PbS, and ZnO) have been prepared by standard colloid−chemical synthetic methods. For CdS, the initial mean radius of 35 Å could be gradually decreased to 7.5 Å by size-sel…
We introduce a kinetic model of coarsening of transient polymer networks during the intermediate stages of phase separation in polymer systems. The model explicitly takes into account the effect of the connectivity of polymer chains. We show that during the intermediate stages the size of the droplet grows according t…
This paper focuses attention on the intrazeolite anchoring of ruthenium carbonyl clusters and their catalytic performances. The synthesis involves the adsorption of metal carbonyl species or metal ion exchange into zeolite cages followed by reductive carbonylation under a mixed CO and H 2 atmosphere. The characterizat…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSynthesis of Soluble Fluorinated Vinyl Ether Copolymers by Ionic Addition of Fluoroolefins to Poly(vinyl alcohol)Andrew E. Feiring and Edward R. WonchobaView Author Information DuPont Central Research & Development, Experimental Station, P.O. Box 80328, Wilmington, Delaware 198…