Materials Literature
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We perform molecular dynamics simulations of repulsive athermal systems sheared at fixed normal load to study the effective temperature TL defined from time-dependent fluctuation-dissipation relations for density. We show that these systems possess two distinct regimes as a function of the ratio TS/V of the granular t…
Abstract Summary: SiO 2 ‐like coatings have been deposited onto silver‐based alloys by means of plasma‐enhanced chemical vapor deposition (PECVD) fed with a tetraethoxysilane/oxygen mixture in order to study their capability to protect the alloys from tarnishing. Chemical and morphological characterization of the coat…
Abstract Dynamic mechanical thermal analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis were used to monitor the degradation of biodegradable blends in soil from vegetal sources consisting of dispersed thermoplastic starch and cellulosic derivatives. First, the viscoelastic behavior of th…
The chelates of europium and terbium with hexafluoroacetylacetone (HFA) and triphenylphoshine oxide (TPPO), Eu∕Tb(HFA)3(TPPO)2, have been synthesized in situ in gel glasses with various concentrations of Eu3+ and Tb3+ ions. The photoluminescence spectra have been measured and the characteristic transitions of Tb3+ and…
Abstract Rectorite/styrene–butadiene copolymer (SBR) nanocomposite was prepared by cocoagulating SBR latex and rectorite/water suspension. Transmission electron microscopy showed that the layers of rectorite were well dispersed in the SBR matrix and the aspect ratio (width/thickness) of it was higher than that of mont…
Abstract Polymer nanocomposites containing several percent of exfoliated layered silicates are materials with a unique weight/performance ratio. The only parameter that is not enhanced, but even decreased, is toughness. This work focused on the toughness enhancement of these advanced systems with polyamide matrix prep…
The potentialities of mesoporous materials both as catalysts and catalytic supports in reactions like alkylation, hydrogenation, and oxidation of various substrates are reviewed. Much of our current research effort is devoted to exploring the mechanistic aspects of the reactions, the role of the catalyst structure, an…
Utilizing a sum rule in a spin-resolved photoelectron spectroscopic experiment with circularly polarized light, we show that the orbital moment in LaTiO3 is strongly reduced from its ionic value, both below and above the Ne el temperature. Using Ti L2,3 x-ray absorption spectroscopy as a local probe, we found that the…
We report experimental measurements of the phase behavior of mixtures of thin (charged semiflexible fd virus) and thick (fd-PEG, fd virus covalently coated with polyethylene glycol) rods with diameter ratio varying from 3.7 to 1.1. The phase diagrams of the rod mixtures reveal isotropic-nematic, isotropic-nematic-nema…
Abstract Natural rubber (NR)–clay (clay is montmorillonite) and chloroprene rubber (CR)–clay nanocomposites were prepared by co‐coagulating the rubber latex and clay aqueous suspension. Transmission electron microscopy showed that the layers of clay were dispersed in the NR matrix at a nano level, and the aspect ratio…
Abstract Summary: We report a new method for the preparation of polyaniline nanoballs by using HAuCl 4 as an oxidizing agent. During the reaction, aniline is oxidized and forms polyaniline whilst the hydrogen tetrachloroaurate is reduced and forms gold nanoparticles. These gold nanoparticles are found to decorate the…
In a recently performed experiment Korovyanko et al [Phys. Rev. B 67, 035114 (2003)] have measured the photo-induced absorption (PA) spectrum of phenyl-disubstituted polyacetylenes (PDPA) from 1$B_{u}$ and 2$A_{g}$ excited states. In 1$B_{u}$ PA spectrum they identified two main features namely PA1 and PA2. While in t…
As is well known the absorption of circularly polarized light in semiconductors results in optical orientation of electron spins and helicity-dependent electric photocurrent, and the absorption of linearly polarized light is accompanied by optical alignment of electron momenta. Here we show that the absorption of unpo…
Neutron scattering studies on powder and single crystals have provided new evidences for unconventional magnetism in Cu2Te2O5Cl2. The compound is built from tetrahedral clusters of S=1/2 Cu2+ spins located on a tetragonal lattice. Magnetic ordering, emerging at TN=18.2 K, leads to a very complex multi-domain, most lik…
This work confirms that not only surface plasmons but many other kinds of electromagnetic eigenmodes should be considered in explaining the values of the transmittivity through a slab bearing a two-dimensional periodic corrugation. Specifically, the role of Brewster-Zennek modes appearing in metallic films exhibiting…
The crystal structure and morphology of the Nd-rich phase in postannealed sintered Nd–Fe–B hard magnets were investigated by transmission electron microscopy (TEM). The Nd-rich phase at grain boundaries thinner than about 2nm was found to be amorphous; as the boundary region broadened, it assumed a face-centered cubic…
Presented are magnetization measurements on a crystal of Fe8 single-molecule magnets using a Hall probe magnetometer. Irradiation with microwaves at frequencies of 92 and 110-120 GHz leads to the observation of electron paramagnetic resonance (EPR) detected via magnetization measurements. A quantitative analysis of th…
The pi-stacking between aromatic oligomers has been extensively studied for many years, although the notion of exploiting this phenomenon as the driving force for molecular actuation has only recently emerged. In this work we examine with MP2 and Car-Parrinello ab initio calculations the actuation properties of a nove…
This letter reports on the superior magnetocaloric properties of La0.7Ca0.3−xSrxMnO3 (x=0.05, 0.10, 0.20, and 0.25) single crystals. Upon 50 kOe applied field, the magnetic entropy changes (ΔSM) reach values of ∼10.5, 7.45, 6.97, and 6.86J∕kgK for x=0.05, 0.10, 0.20, and 0.25 compositions, respectively. The large magn…
To overcome some deficiencies in previous constitutive models of giant magnetostrictive materials, a nonlinear and coupled model is suggested to describe the constitutive relations for a Terfenol-D rod subjected to an axial pre-stress and then located in an axial magnetic field. The numerical simulation by the model p…