Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVNoteSynthesis and Characterization of Anionic and Cationic Poly(ferrocenylsilane) PolyelectrolytesMark A. Hempenius, Fabiane F. Brito, and G. Julius VancsoView Author Information MESA+ Research Institute for Nanotechnology, University of Twente, P.O. Box 217, NL-7500 AE Enschede, The N…
The purpose of this research was to study the influence of the temperature, treatment time, and initial coal particle size on the evolution of the structural order of graphite materials that have been prepared from an anthracite at temperatures >2273 K. Crystalline parameters such as the interlayer spacing and crystal…
A $\ensuremath{\pi}$-electron network in nanographite systems with zigzag edges exhibits strongly localized edge states, which are expected to have peculiar properties. We study effects of electron-electron interactions on ground-state properties of zigzag nanographite ribbons and open-ended zigzag nanotubes by means…
First-principles density-functional calculations are performed within the local-density approximation to study the electronic properties of ${\mathrm{SrZrO}}_{3},$ an insulating $4d$ perovskite, in its high-temperature cubic phase, above 1400 K, as well as the generic $3d$ perovskite ${\mathrm{SrTiO}}_{3},$ which is a…
Four {SiW9O34} units enclose a 14 CuII cluster obtained through halide supramolecular assembly, leading to the polyanion containing the highest number of divalent metal cations (see picture; W blue, Si yellow, Br orange, Cu green, O red).
Giving color to data recording: Upon irradiation with selected wavelengths of light the hexane solution of a fused dithienylethene derivative changes from colorless to yellow, green, black, or blue depending on the wavelength, and irradiation time (see picture). This could be a landmark in the development of new data…
Taming the caged ion: The X-ray crystal structure of an octaphenyl octasilsesquioxane cage that encapsulates a fluoride ion is presented (see picture). The extent of the SiF interaction is low, which causes the cage geometry to not change significantly from that of a normal T8 structure. The crystal structure and the…
We present an extensive first-principles study of the phonons in boron nitride nanotubes using density functional perturbation theory in the local density approximation. Based on the nonsymmorphic rod-group symmetry of the tubes, the Raman- and infrared-active modes at the $\ensuremath{\Gamma}$ point of the one-dimens…
The structural, electronic, and vibrational properties of small-radius single-walled BN nanotubes are studied using the density functional method with the local density approximation. The results show that the chirality preference of BN nanotubes observed in experiments may be explained from the relative stability of…
By means of high resolution neutron powder diffraction at low temperature we have characterized the structural details of ${\mathrm{La}}_{x}{\mathrm{Sr}}_{2\ensuremath{-}x}{\mathrm{FeMoO}}_{6}$ $(0<~\mathrm{x}<~0.5)$ and ${\mathrm{Ca}}_{x}{\mathrm{Sr}}_{2\ensuremath{-}x}{\mathrm{FeMoO}}_{6}$ $(0<~x<~0.6)$…
The influence of average molar mass and shear on the crystallization of isotactic polypropylene ( i PP) has been studied. The Weissenberg number, a dimensionless parameter consisting of the product of the shear rate and a characteristic relaxation time (γ̇ 0 λ r ), provides a criterion to locate the morphological tran…
It is shown that it is possible to significantly modify optical spectra of Bragg multiple quantum well structures by introducing wells with different exciton energies. The reflection spectrum of the resulting structures is characterized by high contrast and tuning possibilities.
The lattice vibrations are determined in the quasi-harmonic approximation for elemental Au and Cu to twice their normal density by first-principles electronic band-structure calculations. It is found for these materials that the important moments of the phonon density of states can be obtained to high accuracy from sh…
To elucidate a novel pressure-temperature phase diagram of the quasi-one-dimensional mixed-stack charge-transfer (CT) complex TTF-CA, we study the quasi-one-dimensional spin-1 Blume-Emery-Griffith (BEG) model. In addition to the local charge transfer energy and the inter-stack polar (dipole-dipole) interaction, we tak…
We have investigated Pd nanowires theoretically, and found that, unlike either metallic or free atomic Pd, they exhibit Hund's rule magnetism. In long, monoatomic wires, we find a spin moment of 0.7 Bohr magnetons per atom, whereas for short, monoatomic wires between bulk leads, the predicted moment is about 0.3 Bohr…
We investigate the band structure of electrons bound on periodic curved surfaces. We have formulated Schrödinger's equation with the Weierstrass representation when the surface is minimal, which is numerically solved. Bands and the Bloch wavefunctions are basically determined by the way in which the ``pipes'' are conn…
We propose a theory of the origin of transport nonuniversality in disordered insulating-conducting compounds based on the interplay between microstructure and tunneling processes between metallic grains dispersed in the insulating host. We show that if the metallic phase is arranged in quasi-one-dimensional chains of…
We report studies of polycrystalline samples of the metallic ferromagnet ${\mathrm{Pr}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{CoO}}_{3}$ through measurements of the magnetization, ac magnetic susceptibility, resistivity, and specific heat. We find an unusual anomaly around ${T}_{A}=120\mathrm{K},$ much below the ferromagne…
We construct a diffuse-interface model of two-phase solidification that quantitatively reproduces the classic free boundary problem on solid-liquid interfaces in the thin-interface limit. Convergence tests and comparisons with boundary integral simulations of eutectic growth show good accuracy for steady-state lamella…
It is found that crystals of molecular nanomagnets exhibit enhanced magnetic relaxation when placed inside a resonant cavity. A strong dependence of the magnetization curve on the geometry of the cavity has been observed, providing indirect evidence of the coherent microwave radiation by the crystals. A similar depend…