Materials Literature
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The jarosites make up the most studied family of {\it kagomé} antiferromagnets. The flexibility of the structure to substitution of the A and B ions allows a wide range of compositions to be synthesised with the general formula AB3(SO4)2(OH)6 (A = Na$^+$, K$^+$, Ag$^+$, Rb$^+$, H3O$^+$, NH4$^+$, 1/2Ba$^{2+}$, and 1/2P…
Group Theory techniques can aid greatly the determination of magnetic structures. The integration of their calculations into new and existing refinement programs is an ongoing development that will simplify and make more rigorous the analysis of experimental data. This paper presents an overview of the practical appli…
The cohesion mechanism of cubic approximant crystals in newly discovered binary quasicrystals, Cd(6)M ( M = Yb or Ca), is studied theoretically. It is found that stabilization due to alloying is obtained if M is an element with low-lying unoccupied d states. This leads to the conclusion that the cohesion of Cd-based c…
Abstract Simple esterification and etherification reactions were applied to steam‐exploded Flax ( Linum usitatissimum ) with the aim of changing the surface properties through modification of fiber surface chemistry. Native and chemically modified cellulose fibers were characterized in terms of thermal stability, surf…
We report on a study of spherical polyelectrolyte brushes that consist of a solid core onto which linear polyelectrolyte chains are chemically grafted. The core particles are made up of solid poly(styrene) and have a radius R of ca. 50 nm. As polyelectrolyte chains the weak polyelectrolyte poly(acrylic acid) or the st…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPolymer Functionalization for Air-Stable n-Type Carbon Nanotube Field-Effect TransistorsMoonsub Shim, Ali Javey, Nadine Wong Shi Kam, and Hongjie DaiView Author Information Department of Chemistry, Stanford University Stanford, California 94305 Cite this: J. Am. Chem.…
Wave propagation in a double negative (DNG) medium, i.e., a medium having negative permittivity and negative permeability, is studied both analytically and numerically. The choices of the square root that leads to the index of refraction and the wave impedance in a DNG medium are determined by imposing analyticity in…
Optical polymers which exhibit no birefringence with any orientation of polymer chains are desirable to realize high performance optical devices that handle polarized light. We defined such polymers as 'zero-birefringence polymer' and demonstrated two methods for synthesizing the zero- birefringence polymers: the rand…
Atomic force microscopy (AFM) is used in contact mode with a conducting tip to probe the conducting network of the conductive polymer polyaniline blended in an insulating polymer matrix. The high resistance contrast and sharp boundaries between conductive and insulating phases is observed down to scales in the 10 nm r…
Abstract Oxides CaO, MgO and a physical mixture of 10% CaO + 90% MgO were used as catalysts for the steam gasification of naphthalene. A synergistic effect in the conversion was observed with the mixture. Catalysts were characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and XPS techn…
Single-walled carbon nanotubes (SWNTs) have been produced in high yield by the dc arc discharge technique under gravity-free conditions. Gravity-free conditions can reduce the convection flow of the buffer gas during the arc discharge, which results in the increase of high thermostatic volume around the arc flame. The…
Imaging of As- and B-doped silicon regions has been performed in a scanning electron microscope operated in the cathode lens mode, with incident electron energies (EP) as low as 15 eV. The doped regions of n+ (As, 2.5×1020 cm−3) and p+ (B, 8×1019 cm−3) on n-type silicon (∼1015 cm−3) show distinct contrast with electro…
Carbon nanotube tapers are a set of nanostructures comprised of straight tubular sections with decreasing diameters, joined to each other via conical funnels and terminated with a hemispherical cap. The funnels are formed with the help of topological defects, which minimally include at least one pentagon-heptagon pair…
Abstract In the present work our experimental results on the energy shifts and energy widths (full width of half‐maximum) of the quasi‐elastic peaks (1–5 keV) obtained using a high‐energy‐resolution electron spectrometer and different (C, Si, Ni and Au) surfaces are compared with those calculated by assuming single el…
NH3-treated mesoporous silica (FSM-16) contains SiNH2 sites which exhibit basic catalytic activity for Knoevenagel condensation; SiNH2 and SiOH pair sites formed at lower NH3-treatment temperatures exhibit higher turnover frequencies (TFs) in comparison with SiNH2 single sites.
The excitation and emission properties of ${\mathrm{Pr}}^{3+}$ and ${\mathrm{Ce}}^{3+}$ doped $M{\mathrm{SO}}_{4}$ ${(M}^{2+}={\mathrm{Ca}}^{2+},$ ${\mathrm{Sr}}^{2+},$ and ${\mathrm{Ba}}^{2+})$ were investigated at 293 and 10 K. The lowest $5d$ level in ${\mathrm{CaSO}}_{4}:{\mathrm{Pr}}^{3+}$ is located below the ${…
Abstract The water sorption of chitosan has been studied at 20 °C. Water transport is governed by a Fickian process for relative humidities lower than 0.4, and in that range of partial pressures, the diffusion coefficient is concentration‐dependent. At a higher activity, anomalous diffusion is observed. The sorption i…
A mesoporous carbon molecular sieve with a hexagonal framework structure (denoted C-MSU-H) has been prepared using a MSU-H silica template that can be assembled from a low cost soluble silicate precursor at near-neutral pH conditions.
The influence of lattice strain and Mg vacancies on the superconducting properties of MgB2 samples has been investigated. High quality samples with sharp superconducting transitions were synthesized. The variation in lattice strain and Mg vacancy concentrations were obtained by varying the synthesis conditions. It was…
Epitaxial thin films of stoichiometric ${\rm LaMnO_3}$ were grown on ${\rm SrTiO_3(110)}$ substrates using the pulsed laser deposition technique. From the high resolution x-ray diffraction measurements, the lattice parameters were determined as a function of temperature and the cooperative Jahn-Teller transition was f…