Materials Literature
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Three novel narrowly distributed rod−coil diblock copolymers, poly(styrene- block -(2,5-bis[4-methoxyphenyl]oxycarbonyl)styrene) (PS- b -PMPCS), with same PS block length and different PMPCS lengths, were synthesized by 2,2,6,6-tetramethyl-1-piperidinyloxy- (TEMPO-) mediated living free radical polymerization. The sel…
A global picture for the structural evolution in the relaxor-ferroelectric solid solution $({\mathrm{PbSc}}_{1/2}{\mathrm{Nb}}_{1/2}{\mathrm{O}}_{3}{)}_{1\ensuremath{-}x}\ensuremath{-}({\mathrm{PbTiO}}_{3}{)}_{x}$ is proposed. Thanks to x-ray profile analysis and Rietveld neutron powder refinement, a monoclinic phase…
We have successfully measured the sliding force for an interlayer of individual multiwall carbon nanotubes using a combination of a well-controlled electrical breakdown process and a manipulation process using a scanning electron microscope. A sliding force of ∼4 nN for an inner layer diameter of 5 nm is maintained co…
We present a theory of the anomalous Hall effect in ferromagnetic $(\mathrm{G}\mathrm{a},\mathrm{M}\mathrm{n})\mathrm{A}\mathrm{s}$ in the regime when conduction is due to phonon-assisted hopping of holes between localized states in the impurity band. We show that the microscopic origin of the anomalous Hall conductiv…
Bubble levitation in an acoustic standing wave is re-examined for conditions relevant to single-bubble sonoluminescence. Unlike a previous examination [Matula et al., J. Acoust. Soc. Am. 102, 1522-1527 (1997)], the stable parameter space [Pa,R0] is accounted for in this realization. Forces such as the added mass force…
The structures, magnetisms, and magneto-optical (MO) Kerr spectra of nanocrystalline ${\mathrm{CoFe}}_{2\ensuremath{-}x}{M}_{x}{\mathrm{O}}_{4}$ $(M=\mathrm{M}\mathrm{n},\mathrm{A}\mathrm{l},\mathrm{S}\mathrm{c})$ thin films have been systematically investigated by means of x-ray diffraction, atomic force microscopy,…
A series of organically modified clays (OMCs) with a surfactant loading range from 0.625 to 2.5 times the cation exchange capacity (CEC) were melt-mixed with maleated polypropylene (PPMA). Wide-angle X-ray diffraction and transmission electron microscopy results of these nanocomposites show that dispersion of clays be…
Optical and electron-spin resonance (ESR) spectroscopy studies of low-temperature electron-irradiated amorphous ${\mathrm{SiO}}_{2}$ were carried out to identify optical transitions of self-trapped holes (STHs). Spectroscopic analysis by means of polarized optical bleaching and thermal annealing has revealed two compo…
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.