Materials Literature
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Two types of current crowding structures were simulated in this work. In each structure, both the pattern of current crowding and the magnitude of the associated current density gradient were examined. Factors like line width, curvature, and conductivity, which affect the crowding behavior, were analyzed. The numerica…
We have measured the collective electronic excitations of the Al(111) surface by means of angle-resolved high-resolution electron-energy-loss spectroscopy. Loss spectra reveal both the monopole and the multipole surface plasmons. The measured dispersion of the monopole surface plasmon is negative, as predicted by calc…
We used x-ray magnetic circular dichroism (XMCD) to obtain element specific magnetization curves. The most common way measuring XMCD in the soft x-ray region is total electron yield (TEY), because of the easy experimental setup and high signal-to-noise ratio compared to fluorescence yield. Surprisingly TEY was used on…
The bcc $\ensuremath{\rightarrow}\ensuremath{\Omega}$ phase transition is diffusionless: two-thirds of the atoms in the $(111)$ planes of the bcc phase collapse into double layers, whereas the third remains a single layer. This transformation is observed in the group-IV elements Ti, Zr, and Hf at high pressure, but it…
Tight-binding calculations are presented for the formation energies of a type of topological defect called the 5-77-5 defect in achiral carbon nanotubes. The calculations show that the defect formation energy is dependent on the chirality and radius of a tube as well as the different orientations of a 5-77-5 defect in…
We report three surprising results regarding the nature of the spatial broken symmetries in the two-dimensional (2D), quarter-filled band with strong electron-electron interactions that provides a microscopic model of the 2:1 cationic organic charge-transfer solids (CTS's). First, in direct contradiction to the predic…
Ferroelectric Bi3.25La0.75Ti3O12 (BLT) thin films were prepared on platinum coated silicon substrate by chemical solution deposition. The layered-perovskite phase was obtained by rapid thermal annealing the spin-on films at 650 or 700 °C for 180 s. Scanning electron micrographs showed uniform surfaces composed of sphe…
The modification of the elastic properties of giant magnetostriction alloy films due to an applied magnetic field (the ΔE effect), has been studied. Two different types of films were deposited on Si substrates: (i) single layers of TbDyFeCo alloys typically 1000 nm thick and (ii) nanocomposite multilayer films of FeCo…
Initial behavior and the subsequent motion of a bubble in liquid nitrogen are investigated experimentally using high-speed photography. A bubble is generated by focusing a pulsed ruby laser into liquid nitrogen at 78.0 K, changing the ambient pressures up to 253.2 kPa which corresponds to the applied pressure (or over…
The new compounds, Sr6Sb6S17, Ba2.62Pb1.38Sb4S10, and Ba3Sb4.66S10 were prepared by the molten polychalcogenide salt method. Sr6Sb6S17 crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 8.2871(9) A, b = 15.352(2) A, c = 22.873(3) A, and Z = 4. This compound presents a new structure type composed of [S…
Cuprous oxide (Cu 2 O) particles coated with polyacrylamide having diameters in the range from 4.8 to 8.6 nm were prepared by a chemical method. The optical absorption of these particles was found to be characterized by excitons with corresponding energies varying from 2.6 to 2.25 eV in the particle size range mention…
Ultrasonic irradiation is able to modify the course of several photochemical reactions, especially bimolecular, proceeding via triplet states. These effects were illustrated in the study of benzophenone photopinacolization in ethanol. The rates and yields increase when sonication is applied simultaneously to UV irradi…
Due to a simple band structure, the excitons in cuprous oxide $({\mathrm{Cu}}_{2}\mathrm{O})$ are a model system for kinetic studies. Cuprous oxide appeared to be a host for a Bose-Einstein condensate of excitons, as the excitons showed transient kinetic energy distributions which matched those expected for a Bose gas…
The optical properties of nanographite ribbons are studied within the gradient approximation. The spectral function exhibits rich peak structures due to the divergencies in its density of states. Whether there are prominent peak structures is mainly determined by the geometric structure, the edge structure and the wid…
Extended x-ray absorption fine structure spectra of monoclinic zirconia (m-ZrO2) and of amorphous zirconia (a-ZrO2) in form of a thin film are analyzed by reverse Monte Carlo simulations. Partial pair distribution functions (PDF, gZr–O and gZr–Zr) are extracted. Coordination numbers and distances determined for m-ZrO2…
The crystal structures of M10(PO4)6X2, where M = Ca or Pb and X = OH¯, F¯, Cl¯ or Br¯, have been determined by Rietveld refinement of powder synchrotron X-ray and neutron diffraction data. All the compounds are hexagonal with space group P 63/ m . For the calcium compounds, the lattice parameters are a = 9.4302(5), 9.…
The low-frequency optical properties of single-wall carbon nanotube bundles are studied within the gradient approximation. The nanotube geometry (diameter and chiral angle) and the polarization direction strongly affect the optical absorption function, the dielectric function, the loss function, and the reflectance. T…
A general theory of the electronic relaxation of an S state complexed paramagnetic metal ion (Mn2+, Gd3+) in solution is developed. Contrarily to the usual assumption, the electronic relaxation is not only due to the effects of the transient zero field splitting, but is strongly influenced by the static crystal field…
When using electron-energy-loss spectroscopy (EELS) to quantify the ${\mathrm{sp}}^{2}{/sp}^{3}$ bonding fraction in thin film carbon, the spectrum taken from the film must be compared to that of a suitable known standard. In contrast to the work of Berger [S. D. Berger and D. R. McKenzie, Philos. Mag. Lett. 57, 285 (…
The work function of tetrahedral amorphous carbon (ta-C) has been measured by Kelvin probe to lie in the range 4–5 eV, irrespective of its sp3 content or nitrogen addition. This implies that the surface barrier to emission is dominant and that emission changes caused by sp3 bonding or nitrogen addition are not directl…