Materials Literature
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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…
Lattices in three dimensions are oft studied from the ``reciprocal space'' perspective of diffraction. Today, the full lattice of a crystal can often be inferred from direct-space information about three sets of non-parallel lattice planes. Such data can come from electron-phase or Z contrast images taken at two tilts…
We report experimental evidence showing a direct correlation between the alignment of carbon nanofibers (CNFs) prepared by plasma-enhanced chemical-vapor deposition and the location of the catalyst particle during CNF growth. In particular, we find that CNFs that have a catalyst particle at the tip (i.e., growth proce…
Of the ``presolar particles'' extracted from carbonaceous chondrite dissolution residues, i.e. of those particles which show isotopic evidence of solidification in the neighborhood of other stars prior to the origin of our solar system, one subset has an interesting concentric graphite-rim/graphene-core structure. We…
Small polaron behavior in a two dimensional honeycomb net is studied by applying the strong coupling perturbative method to the Holstein molecular crystal model. We find that small optical polarons can be mobile also if the electrons are strongly coupled to the lattice. Before the polarons localize and become very hea…
We study the Aharonov-Bohm effect in a coupled 2$\times$2 quantum dot array with two-terminals. A striking conductance dip arising from the Fano interference is found as the energy levels of the intermediate dots are mismatched, which is lifted in the presence of a magnetic flux. A novel five peak structure is observe…
The syntheses and crystal structures of the eight-membered cyclo -stannasiloxanes cyclo -[ t -Bu(OH)Si(OSn t -Bu 2 O) 2 Si(OH) t -Bu] ( 1 ) and cyclo -{ t -Bu 2 Si[OSn(CH 2 SiMe 3 ) 2 O] 2 Si t -Bu 2 } ( 2 ) as well as the synthesis of the six-membered cyclo -stannasiloxane cyclo -{ t -Bu 2 Si[OSn(CH 2 SiMe 3 ) 2 ] 2…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTBridging the Ruddlesden−Popper and the Aurivillius Phases: Synthesis and Structure of a Novel Series of Layered Perovskite Oxides, (BiO)LnTiO4 (Ln = La, Nd, Sm)Thathan Sivakumar, Ram Seshadri, and Jagannatha GopalakrishnanView Author Information Solid State and Structu…
Dynamic secondary ion mass spectrometry was performed to determine the dynamics of thin free-standing polystyrene films by investigating probe diffusion in a high molecular weight polymer matrix. It is found that the temperature dependence of the diffusion of small molecular probes can be described by the WLF equation…