Materials Literature
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In this paper, the spectroscopic properties of bismuth borate glasses doped with different Nd 3+ concentrations have been investigated. The intensity parameters Ω t ( t =2, 4, 6), spontaneous emission probability, fluorescence lifetime, radiative quantum efficiency, fluorescence branching ratio, and stimulated emissio…
Multiple-wavelength distributed-feedback lasers are made from multilayered composites by utilizing the solution-processing ease of cadmium selenide semiconductor nanocrystals and soft lithography. The Figure shows three types of emission obtained from such structures across a wide range of the visible spectrum: fluore…
Organic molecules have been incorporated into the pore system of mesoporous TiO 2 and ZrO 2 xerogels and thin films. Surface-modifying functions include alkyl, aryl, amino, sulfonate, thiol, and polyol. Phosphate, phosphonate, carboxylate, and polyphenol were used as grafting groups. The incorporation of these functio…
This paper describes the synthesis of core-shell CdSe/CdS quantum dots (QDs) in aqueous solution by a simple photoassisted method. CdSe was prepared from cadmium nitrate and 1,1-dimethylselenourea precursors under illumination for up to 3 h using a pulsed Nd:YAG laser at 532 nm. The effects that the temperature and th…
The aim of this work is to measure the hydrogen transport and solubility parameters in the commercial alumina. Measurements are conducted using a time‐dependent permeation method over the temperature range 1273–1673 K with hydrogen driving pressures in the range 10 4 –10 5 Pa (100–1000 mbar). A half‐power pressure dep…
Abstract This paper discusses the development of a finite volume model for a planar solid oxide fuel cell. Two different levels of detail for the definition of the basic cell elements are considered, the first with the assumption of isothermal behavior for a finite volume, defined by a portion of the cell PEN structur…
A combination of methods, Bragg diffraction, small‐angle X‐ray scattering (SAXS), and transmission electron microscopy, is applied to the characterization of nanodomains and nanocrystals in polymer‐derived ceramics (PDCs). Detailed study of two materials, silicon carbonitride (SiCN) and a SiCN–zirconia nanocomposite,…
CdS/dendrimer nanocomposites can be synthesized from methanolic Cd(2+) and S(2-) with amine-terminated polyamidoamine dendrimers of generation 8 (G8NH(2)) as stabilizers. By controlling the preparation conditions, nanoparticles with diameters < or = 2 nm can be obtained with a narrow size distribution. They show blue…
Abstract The quiescent annealing of four different co‐continuous polystyrene/high‐density polyethylene blends of widely different viscosity ratios were examined at three different temperatures. In addition, the coarsening of a co‐continuous poly(methyl‐methacrylate)/high‐density polyethylene blend was also studied. Si…
The nanostructure of amorphous carbon thin films is described in terms of a disordered nanometer-sized conductive $s{p}^{2}$ phase embedded in an electrically insulating $s{p}^{3}$ matrix. It is shown that the degree of clustering and disorder within the $s{p}^{2}$ phase plays a determining role in the electronic prop…
Nanorods of the photomagnetic coordination network Mo(CN)8Cu2 coated with polyvinylpyrrolidone were prepared and exhibit an enhanced effect upon irradiation when compared to the bulk.
In an effort to extend the pressure range for electron-based spectroscopies from ultrahigh vacuum into the so-called pressure gap region, we have built a new apparatus for in situ x-ray photoelectron spectroscopy up to 1mbar. The principle of the experimental setup is based on a modified hemispherical electron energy…
The microwave permittivity and permeability of Co2Z barium ferrite composite samples are measured as functions of frequency and volume fraction of the ferrite. Magnetostatic properties of the bulk ferrite are determined. This allows Snoek’s law [J. L. Snoek, Physica 14, 204 (1948)] to be verified by comparing the micr…
A previously developed analytical formulation has been modified in order to more accurately account for the effects of hydrostatic stresses on the nonlinear, strain rate dependent deformation of polymer matrix composites. State variable constitutive equations originally developed for metals have been modified in order…
Polymer modification of carbon nanotubes is accomplished using a “grafting-to” approach. Radicals formed by the thermolysis of poly(2-vinylpyridine) terminated with a radical-stabilizing nitroxide can react with the surface of nanotubes (see Figure), resulting in grafting densities up to 12 wt.-%. The modified nanotub…
Micro- and nanopatterns of polymer brushes (see Figure) are fabricated using a “top–down/bottom–up” approach. A silicon surface is patterned with gold using lift-off electron-beam lithography (“top–down”), and the resulting pattern is then amplified by surface-initiated atom-transfer radical polymerization (“bottom–up…
Cerium oxide solid samples were prepared via precipitation from aqueous solution of hydrous cerium(III) nitrate in the presence of different percentages of hydrogen peroxide (H 2 O 2 ) as model corrosion inhibiting coatings materials for aluminum alloys. X-ray absorption spectroscopy at the Ce L III -edge was applied…
We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiOx, 0&lt;x&lt;2) films by high-vacuum annealing and dry oxidation. The SiOx films were deposited by plasma-enhanced chemical vapor deposition at different nitrous–oxide/silane flow ratios. The phy…
Abstract Raman spectra of binary sodium silicates in various components were calculated by the self‐consistent field molecular orbital ab initio calculation quantum chemical (QC) method with several polysilicon–oxygen tetrahedral model clusters with both 6–31G and 6–31G(d) basis sets being applied. Relevant pure anion…
A controlled and scalable multistep purification method has been developed to remove iron impurity and nonnanotube carbon materials from raw single-walled carbon nanotubes (SWNTs) produced in the HiPco (high-pressure CO) process. In this study, iron nanoparticles, coated by carbon, are exposed and oxidized by multiple…