Materials Literature
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This paper concerns theoretical and experimental investigations of the effect of a conductor coating on the onset voltage of a corona on overhead transmission-line conductors. The onset voltage for a self-maintained discharge on the basis of discharge physics is evaluated. This calls first for accurate calculation of…
The fate of ∼0.5 M tetraethyl orthosilicate (TEOS) in HNO 3 solutions (pH 2−3) was followed by “in situ” ATR−FTIR spectroscopy. ATR spectra with excellent signal-to-noise ratios were obtained with collection times of 2 min. A qualitative examination of spectra measured at different reaction times showed that TEOS was…
The synthesis of the cyclophane-type molecular dyads 1 and 1 . Zn was accomplished by Bingel macrocyclization of porphyrin-tethered bis-malonates 5 or 5 . Zn, respectively, with C60 (Scheme). In these macrocycles, the doubly bridged porphyrin adopts a close, tangential orientation relative to the surface of the C-sphe…
The crystal structure of Valonia cellulose Iβ is determined by X-ray fiber diffraction analysis. A careful reanalysis of two existing X-ray diffraction data sets for Valonia cellulose I leads to a consistent, definitive structure of the β-phase. The results resolve ambiguities in existing X-ray analyses between “paral…
We show that quantum correlations induced by electron-electron interactions in the presence of random impurity scattering can play an important role in the thermal stabilization of amorphous Hume-Rothery systems: When there is strong backscattering off local, concentrical ion clusters, the static electron density resp…
We describe a new, biased Monte Carlo scheme to determine the crystal structures of zeolites from powder diffraction data. We test the method on all publicly known zeolite materials, with success in all cases. We show that the method of parallel tempering is a powerful supplement to the biased Monte Carlo.
Thermoluminescence glow-curve deconvolution (GCD) functions are proposed for first, second and general orders of kinetics. The free parameters of the GCD functions are the maximum peak intensity and the maximum peak temperature , which can be obtained experimentally. The activation energy ( E ) and the order of kineti…
We study, using simulations, the steady-state flow of dry sand driven by gravity in two-dimensions. An investigation of the microscopic grain dynamics reveals that grains remain separated but with a power-law distribution of distances and times between collisions. While there are large random grain velocities, many of…
Raman scattering in the quarter-filled spin ladder system alpha'-NaV_2O_5 shows in the dimerized singlet ground state ($T \leq T_{SP}=35K$) an unexpected sequence of three magnetic bound states. Our results suggest that the recently proposed mapping onto an effective spin chain for $T > T_{SP}$ has to be given up in f…
Magnetic fluids are colloidal suspensions of ferromagnetic particles covered with a surfactant layer, dispersed in a host liquid. The existence of cooperative phenomena in such magnetic colloidal systems, makes the determining of their physical properties a difficult task. In the framework of statistical mechanics, ta…
The crystal structures of Na3 [H6CoMo6O24].8H2O and K6 [H4Co2Mo10O38].7H2O have been determined by X-ray diffraction. The monomer, Na3 [H6CoMo6O24].8H2O, is triclinic, space group P-1, a 6·451(1), b 10·866(2), c 10·922(2) Å, α 109·20(1), β 106·90(1), γ 95·43(1)°, V 676·3(2) Å3, Z 1, and the structure was solved to an…
The room-temperature single-crystal X-ray diffraction determined structures of the Mn(tpp)Br.C7H8, Mn(tpp)(NCO), Mn(tpp)I.C7H8, Mn(tpp)(CO2CH3).0·5C7H8, and Mn(tpp)(NCS).0·5C7H8 complexs are described. The monoclinic P 21/ c unit cell of Mn(tpp)(NCO) has a 14·82(1), b 17·136(5), c 14·576(5) Å, ß 111·41(5)°, V 3446(3)…
The dielectric response of the relaxor ferroelectric (PMN) is found to be a non-analytical function of the ac field, with the absolute value of the non-linear component of the polarization given by . The dependence on the temperature, T , and frequency, , of the exponent manifests itself in the form of a crossover in…
Multiwall carbon nanotubes can be bent by changing the current density of the electron beam in a transmission electron microscope. The effect could be observed in a small fraction of nanotubes in the investigated samples. The bending can be varied continuously, is reversible, and highly reproducible. On removing the f…
A method for lowering the processing temperature of PbZr1−xTixO3 (PZT) films was developed utilizing a laser-assisted two-step process. In the first step, perovskite phase was initiated in the PZT films to a furnace anneal at low temperatures in the range of 470–550 °C, depending on the Zr/Ti ratio. Later, the films w…
Ab initio calculations based on density functional theory and generalized gradient approximation reveal many unusual features of stoichiometric $(\mathrm{MnO}{)}_{x}$ $(x\ensuremath{\le}9)$ clusters that contrast with their bulk behavior. The clusters are ferromagnetic and carry atomiclike magnetic moments ranging fro…
The use of anodic oxidation as a post-treatment of porous silicon has been investigated to enhance the external quantum efficiency of electroluminescence from a device based on a thin transparent indium tin oxide contact on porosified n+-type silicon. Enhancement in external quantum efficiency of three orders of magni…
Dispersing 1D bands have been observed for the first time in an organic conductor by high resolution photoemission experiments on TTF-TCNQ (tetrathiafulvalene-tetracyanoquinodimethane). Their properties are extremely unusual: the bandwidth is much larger than traditional estimates, and the quasiparticle states are str…
The ac field dependence of dielectric response of sol-gel derived Pb(Zr, Ti)O3 thin films is presented. The analysis of amplitude and phase angle of first and third harmonic of the polarization at subswitching fields shows that a description of the dielectric nonlinearity by the classical polynomial approximation is i…
Phase transitions in submicrometric Ga droplets confined in epoxy resin are studied by combining energy-dispersive x-ray diffraction (EDXRD), x-ray absorption fine structure, and single-energy x-ray absorption. The restricted fluid is undercooled down to 150 K while the melting point is depressed down to 254 K. Meltin…