Materials Literature
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The effect of dc electric field (E) on the dielectric properties of Ba(Ti0.7Zr0.3)O3 ceramics with an obvious ferroelectric-relaxor behavior (Tm∼229 K, 10 kHz) is reported. The dielectric constant is greatly suppressed and a low loss is obtained under dc electric fields (⩽40 kV/cm). The low loss (tan δ∼0.002) and high…
We review the basic ideas of the dynamical mean field theory (DMFT) and some of the insights into the electronic structure of strongly correlated electrons obtained by this method in the context of model Hamiltonians. We then discuss the perspectives for carrying out more realistic DMFT studies of strongly correlated…
We present a density-functional (DF) study of structures of Si cage clusters that encapsulate metal atoms. As a prototypical example, the case of WSi$_{n}$ clusters is shown. To obtain the low-energy clusters in efficient and unbiased ways, genetic-like geometry updates have been performed for generating inputs for su…
We observe a strong correlation between magnetization relaxation and electrical resistivity in thin Permalloy (Ni$_{81}$Fe$_{19}$, ``Py'') films. Electron scattering rates in the films were affected by varying film thickness and deposition conditions. This shows that the magnetization relaxation mechanism is analogous…
This letter describes a method to improve the alignment of single-wall carbon nanotubes in macroscopic fibers produced by a simple spinning process. By contrast to classical composite fibers, where the nanotubes are embedded in a polymeric matrix, they consist of an interconnected network of polymers and nanotubes. Th…
We study different emission regimes in close-packed films of chemically synthesized CdSe nanoparticles [nanocrystal quantum dots (NQDs)]. We observe that the NQD photoluminescence is dominated by excitons and biexcitons, respectively, before and after the threshold for stimulated emission. Furthermore, we demonstrate…
Shear band development in consolidated nanocrystalline and ultrafine-grained Fe has been monitored as a function of overall strain from the onset of plastic deformation. The deformation mechanisms of the grains inside the shear bands, the origin of the inhomogeneous deformation, and the propensity for shear localizati…
The heterostructures of Zn–ZnO coaxial nanocables and ZnO nanotubes with an average diameter of 30 nm have been synthesized by simple pyrolysis of zinc acetylacetonate. High-resolution transmission electron microscopy analyses reveal that the Zn core and the ZnO sheath of the nanocables have an epitaxial relationship…
We use confocal microscopy to study particle motion in colloidal systems. Near the glass transition, motion is inhibited, as particles spend time trapped in transient "cages" formed by neighboring particles. We measure the cage sizes and lifetimes, which, respectively, shrink and grow as the glass transition approache…
The magnetocaloric effect (MCE) originated from the itinerant-electron metamagnetic transition for La(FexSi1−x)13 compounds has been investigated. With increasing Fe concentration, the MCE is enhanced and both the isothermal magnetic entropy change ΔSm and the adiabatic temperature change ΔTad for the compound with x=…
We present calculations of quantized conductance and magnetoresistance in nanosize point contacts between two ferromagnetic metals. When conductance is open for only one conduction electrons spin-projection, the magnitude of magnetoresistance is limited by the rate of conduction electron spin-reversal processes. For t…
The stress profile and reorientation of grains, in response to a point force applied to a preloaded two dimensional granular system, are calculated in the context of a continuum theory that incorporates the texture of the packing. When high friction prevents slip at the inter-grain contacts, an anisotropic packing pro…
Molecular dynamics simulations of the diffusion of limonene into molten polyethylene were performed in order to explore the possibility of using atomistic simulations to predict the diffusion of “larger” solute molecules in polymers. The system contained 6000 anisotropic united atom methylene units with a molar mass o…
A single crystal of KVTeO(5), potassium vanadium tellurite, has been grown. The present structure determination has been conducted together with the refinement of the NaVTeO(5) homologue, sodium vanadium tellurite, for the sake of precise comparison. The network consists of [VTeO(5)](n) ribbons built up by VO(4) tetra…
Using the dynamic density functional (DDF) simulation technique, we studied the domain morphology and dynamics of phase separation in a mixture of long and short block copolymers. The simulation results well reproduce the recent results of the X-ray scattering experiment and the TEM observation on a mixture of long an…
This work reexamines and updates earlier investigations on the phase behaviour of the Gay-Berne liquid crystal model, concentrating on the effect of varying temperature. Constant volume and constant pressure Monte Carlo simulations are combined for systems consisting of N = 500 molecules along different isotherms over…
Copper ions on over-exchanged Cu−MCM-22 were monitored by CO and NO adsorption at 300 K and NO adsorption at 77 K. Two different species of both Cu(I) and Cu(II) ions were produced by vacuum thermal treatment at 823 K. Cu I −CO complexes were formed upon CO adsorption and converted to Cu I −(CO) 2 complexes upon incre…
We propose a new theoretical method to study hydrogen-bonded supramolecular liquid crystals. It is based on our recent theory of associating polymer solutions combined with McMillan's molecular theory of liquid crystallization. We derive phase diagrams of supramolecular liquid crystals consisting of two different spec…
The processes governing adsorption of poly( o -methoxyaniline) (POMA) are analyzed by investigating the kinetics of adsorption and adsorption isotherms of a POMA layer on already adsorbed layer-by-layer films of POMA/poly(ethenesulfonic acid) (PVS). The kinetics of adsorption comprises two steps, namely, a first-order…
Samples of poly(2,2‘-dioxybiphenylphosphazene) were prepared according to procedures previously reported in the literature and submitted to thermal degradation at temperatures between 100 and 200 °C during periods of time ranging from 6 to 250 h. Experimental characterization of the parent polymer and the degraded sam…