Materials Literature
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Specific heat measurements were carried out on the closely related spin-chain oxides Ca3Co2O6 and Ca3CoRhO6. Both compounds consist of Ising magnetic chains that are arranged on a triangular lattice. The spin coupling along and between the chains are ferromagnetic and antiferromagnetic, respectively. Geometrical frust…
Ultrafast intersubband excitation of electrons in tunnell-coupled wells is studied depending on the structure parameters, the duration of the infrared pump and the detuning frequency. The temporal dependencies of the photoinduced concentration and dipole moment are obtained for two cases of transitions: from the singl…
For antiferromagnetically coupled Fe/Cr multilayers the low field contribution to the resistivity, which is caused by the domain walls, is strongly enhanced at low temperatures. The low temperature resistivity varies according to a power law with the exponent about 0.7 to 1. This behavior can not be explained assuming…
In binary metallic systems like the Pd--Er alloys charged with hydrogen the observed structure evolution exhibits complex dynamics. It is characterized by non-monotonic time variations in an Er-rich fraction respect with an Er-poor fraction observed experimentally. The present paper proposes a qualitative model for th…
Several of the $M{\mathrm{Cd}}_{6}$ approximants $(M=\mathrm{Pr},$ Nd, Sm, Eu, Gd, Dy, Yb, Y, and Ca) to the $M{\mathrm{Cd}}_{5.7}$ quasicrystals $(M=\mathrm{Yb}$ and Ca) have been synthesized and their structures have been refined from single-crystal x-ray-diffraction data; the different types of disorder of the cent…
Monolithic carbon possessing hierarchical, multimodal porosity has been prepared by nano‐casting of monolithic, meso‐ and macroporous silica. The carbon monolith (right in Figure) is a positive replica of the silica monolith on the micrometer scale, but a negative replica on the nanometer scale. The diameter of the fu…
Ionization potentials Ip, electron affinities E.A., and the quantum confinement in CdSe nanocrystals were determined by means of cyclic voltammetry. The results were compared to values obtained from spectroscopic measurements, especially UV/vis absorption and photoluminescence emission spectra. Absolute band gap posit…
Carbon nanotubes have been proposed as promising hydrogen storage materials for the automotive industry. By theoretical analyses and total-energy density functional theory calculations, we show that contribution from physisorption in nanotubes, though significant at liquid nitrogen temperature, should be negligible at…
Frequency and temperature dependences of dielectric permittivity and electric modulus of pure and Ba-doped Bi2Ti4O11 were studied in the ranges of 10−1–106 Hz and −150–350 °C, respectively. We found that the antiferroelectric phase transition temperature of Bi2Ti4O11 decreases with Ba doping. In the permittivity studi…
Wafer-scale fabrication of ferroelectric oxide nanoshell tubes as well as ordered nanotube arrays have been accomplished using a simple and convenient fabrication method that allows full tailoring of tube dimensions as well as array pattern and size. Using different silicon and alumina templates, barium titanate and l…
Single-walled carbon nanotubes were oxidized by a technique previously developed for the oxidation of graphite to graphite oxide (GO). This process involves treatment with concentrated H(2)SO(4) containing (NH(4))(2)S(2)O(8) and P(2)O(5), followed by H(2)SO(4) and KMnO(4). Oxidation results in complete exfoliation of…
From extensive molecular dynamics simulations on immiscible two-phase flows, we find the relative slipping between the fluids and the solid wall everywhere to follow the generalized Navier boundary condition, in which the amount of slipping is proportional to the sum of tangential viscous stress and the uncompensated…
The generation of spherical colloids of titania with uniform diameters (see Figure for an SEM image) has been achieved using a new precursor. By varying the concentration of titanium glycolate in acetone the diameter of these spherical colloids could be controlled in the 200–500 nm range. The as‐synthesized colloids c…
Abstract Ordered molecular materials are increasingly used in active electronic and photonic organic devices. In this progress report we discuss whether the self‐assembling properties and supramolecular structures of liquid crystals can be tailored to improve such devices. Recent developments in charge‐transporting an…
The creation of continuous nanoscale composite fibrils from carbon nanotubes using an electrospinning process is reported. Nanotube bundles align in the fiber, and upon heat treatment, the composite fibrils are carbonized at 1100 °C to form the SWNT/carbon yarns. The fibrils show superior mechanical properties and can…
In this paper, we report the complete synthesis and characterization procedures to generate highly organized and oriented mesoporous titania thin films, using poly(ethylene oxide) (PEO)-based templates. Controlled conditions in the deposition, postsynthesis, and thermal treatment steps allow one to tailor the final me…
Abstract A ternary blend of the PA6 matrix with a finely dispersed rigid polymer and elastomer is a system with well‐balanced mechanical properties. Its micromechanical behavior, especially that of the elastomer phase, apparently differs from corresponding binary mixtures. This study shows the influence of the elastom…
Single crystals of monoclinic BaY2F/sub 8/, doped with different Nd/sup 3+/ concentrations, were successfully grown by means of the Czochralski method. Here, we present a polarized infrared (IR) spectroscopic investigation and diode-pumped continuous-wave laser results in the 1 μm wavelength region. Moreover for the f…
Abstract H1 technology needlepunching machinery is one of the recent developments in the needleloom technology. H1 technology needlepunching nonwoven machinery has been effectively utilized to develop a set of nonwoven substrates at different punching rates. The effect of needlepunching speeds on the frictional proper…
Electrical properties of Au and Ag Schottky diodes prepared on epiready (0001)Zn surfaces of bulk n-ZnO crystals with electron concentration close to 1017 cm−3 were studied after various surface cleaning treatments. The lowest reverse currents were obtained with simple cleaning of the surface in organic solvents while…