Materials Literature
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We present a density functional study of zigzag carbon nanotubes containing potassium atoms inside. We find that the effect of potassium doping is not simple charge transfer. The nearly free electron state of nanotube couples with the $\mathrm{K} 4s$ orbital. The state comes downward as the tube is thicker and crosses…
The reaction of 2-(dimethylamino)phenylhydroxamic acid (2-dmAphaH) with NiSO(4).6H2O gives the complex [Ni7(2-dmAphaH-1)2(2-dmApha)8(H2O)2]SO(4).15H2O uniquely exhibiting four distinct hydroxamate binding modes, two of which are novel, and showing both antiferromagnetic and ferromagnetic interactions in contrast to [C…
We introduce the density-matrix renormalization-group method as an efficient computational tool for one-exciton approximations with off-diagonal disorder (single-particle problems). This method allows us to reduce the computational effort by targeting only a few low-lying eigenstates at each statistical sampling, in c…
The problem of the observable equilibrium domain structure (DS) in pure antiferromagnets is investigated with the use of continuous elasticity theory. It is shown that the difference between the bulk and surface magnetoelastic strains causes imaginary `incompatibility elastic charges' analogous to the surface `magneti…
We study the linewidth of the surface plasmon resonance in the optical absorption spectrum of metallic nanoparticles, when the decay into electron-hole pairs is the dominant channel. Within a semiclassical approach, we find that the electron-hole density-density correlation oscillates as a function of the size of the…
The reaction between ferric fluoride trihydrate and pyridine in hot methanol produced yellow-brown crystals of (PyH)5.[Fe13O4F24(OMe)12].4H2O.CH3OH. The anionic complex [Fe13O4F24(OMe)12]5- (1), which has a full Td symmetry, is the first example of an open-shell Keggin ion consisting of 13 high-spin d5 iron(III) atoms…
Quantum conductivity of a wide class of carbon nanotube Y junctions is calculated using an efficient Green's function embedding scheme. Our results indicate that rectification and switching properties of these junctions depend strongly on the symmetry and to a lesser degree on chirality. We find that a zig-zag tube fo…
Macromolecules or colloids in solution can serve as large-scale models for atoms and simple molecules. But as Frenkel explains in his Perspective, this is not all. Colloidal suspensions can also form new states of matter. He highlights the reports by Velikov et al. and Pham et al., who demonstrate how the properties o…
Ideal nanowire interconnects for nanoelectronics will be refractory, covalently bonded, and highly conductive, irrespective of crystallographic orientation. Theoretical studies suggest that boron nanotubes should be stable and exhibit higher electrical conductivities than those of carbon nanotubes. We describe CVD gro…
We report on a study of pressure-dependent structural properties of LaAlO 3 , which is considered to be a model material of the class of `tilted' perovskites. Our high-pressure investigation by means of Raman spectroscopy and synchrotron radiation shows that LaAlO 3 presents structural instabilities under pressure and…
We have investigated the electronic structure of capped carbon nanotubes under electric fields by density functional calculations. The calculated effective work function of the capped armchair nanotubes decreases linearly with increasing electric fields, whereas that of the metal tip decreases quadratically. We analyz…
Using time-resolved photoluminescence measurements, the recombination rate in an In$_{0.18}$Ga$_{0.82}$N/GaN quantum well (QW) is shown to be greatly enhanced when spontaneous emission is resonantly coupled to a silver surface plasmon. The rate of enhanced spontaneous emission into the surface plasmon was as much as 9…
Taking into account both random impurity distribution and thermal fluctuations of localized spins, we have performed a model calculation for the carrier (hole) state in Ga$_{1-x}$Mn$_x$As by using the coherent potential approximation (CPA). The result reveals that a {\it p}-hole in the band tail of Ga$_{1-x}$Mn$_x$As…
In this communication we suggest a formulation of the optical conductivity as a convolution of an energy-resolved joint density of states and an energy-frequency labelled transition rate. Our final aim is to develop a scheme based on the augmented space recursion for random systems. In order to gain confidence in our…
Strained thin films of charge/orbital-ordered (CO/OO) Nd 0.5 Ca 0.5 MnO 3 with various thicknesses have been grown on (100) SrTiO 3 and (100) LaAlO 3 substrates, by using the pulsed laser deposition technique. The thickness of the films drastically influences the transport properties. As the thickness decreases, the C…
We have investigated electronic structures of a room-temperature-diluted magnetic semiconductor: Co-doped anatase ${\mathrm{TiO}}_{2}.$ We have obtained the half-metallic ground state in the local-spin-density approximation (LSDA) and the insulating ground state in the $\mathrm{LSDA}+U+\mathrm{SO}$ incorporating the s…
Physical properties of semiconducting ${\mathrm{CdF}}_{2}$ crystals doped with In are determined from measurements of the radio-frequency response of a sample with Schottky barriers at frequencies $10\ensuremath{-}{10}^{6} \mathrm{Hz}.$ The dielectric constant, the dc conductivity, the activation energy of the amphote…
Two-dimensional (2-D) ordered mesoporous silicas were synthesized following the literature synthesis procedures using two different silica sources (tetraethyl orthosilicate and sodium silicate) and poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide) triblock copolymer template under acidic and neutral synt…
In this work, we report the synthesis of CdSe/CdS, CdSe/ZnS, and CdSe/ZnSe core/shell and CdSe/CdS alloy nanoparticles using bis(hexyl(methyl)dithio-/-diselenocarbamato)cadmium(II)/zinc(II) compounds as single-source precursors. We compare the optical properties of the core/shell nanoparticles in relation to those of…
Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed comprise organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recen…