Materials Literature
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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<x<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…
The fine structure of thin films of poly(styrene- block -4-vinylpyridine) copolymer−2-(4‘-hydroxybenzeneazo)benzoic acid (PS-PVP+HABA) assembly has been studied using the combination of atomic force microscopy, ellipsometry, X-ray reflectivity, GISAXS, XPS, and XPEEM. The films consist of cylindrical nanodomains forme…
Dynamics of regio-regulated Poly(4-methylthiazole-2,5-diyl) [HH-P4MeTz] was inves tigated by solid-state 1H, 2D, 13C NMR spectroscopies, and differential scanning calorimetry(DSC) measurements. DSC, 2D quadrupolar echo NMR, 13C cross-polarization and magic-angle spinning(CPMAS) NMR, and 2D spin-echo(2DSE) CPMAS NMR sp…
Magnetoresistance (MR) and magnetization (d.c and a.c) measurements have been carried out on the manganites, (La0.7-2xEux)(Ca0.3Srx)MnO3 (0.05
A theoretical modeling of the oxygen diffusivity in silicon and germanium crystals both at normal and high hydrostatic pressure has been carried out using molecular mechanics, semiempirical and ab initio methods. It was established that the diffusion process of an interstitial oxygen atom (Oi) is controlled by the opt…
Thin films of the misfit cobaltite Ca3Co4O9 were grown on (0001)-oriented (c cut) sapphire substrates, using pulsed-laser deposition techniques. The dependence of the thermoelectric/transport properties on the film growth conditions was investigated. The optimal conditions (for low resistivities) were found to be 600°…
Silica-coated gold nanoparticles were assembled on carbon nanotubes by polymer wrapping and layer-by-layer assembly (see Figure). The procedure was applied to ordered arrays of vertically aligned nanotubes, resulting in parallel nanotubes of compact nanoparticle monolayers for potential use in photonics.
We introduce a sequential model for the deposition and aggregation of particles in the submonolayer regime. Once a particle has been randomly deposited on the substrate, it sticks to the closest atom or island within a distance \ell, otherwise it sticks to the deposition site. We study this model both numerically and…
The (111) surface of CaF$_2$ has been intensively studied with large-amplitude frequency-modulation atomic force microscopy and atomic contrast formation is now well understood. It has been shown that the apparent contrast patterns obtained with a polar tip strongly depend on the tip terminating ion and three sub-latt…
The Hydrodynamics of Superfluid Turbulence (HST) describes the flows (or counterflows) of HeII in the presence of a chaotic set of vortex filaments, so called superfluid turbulence. The HST equations govern both a slow variation of the hydrodynamic variables due to dissipation related to the vortex tangle and fast pro…