Materials Literature
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We report a new photoluminescence process in epitaxial Si1−xGex layers grown on Si by rapid thermal chemical vapor deposition which we attribute to the recombination of excitons localized at random alloy fluctuations. This luminescence is characterized by saturation at very low excitation densities (≂100 μW cm−2), ver…
The synthesis of SmCo5 by the chemical reduction of Sm2O3 during mechanical alloying has been investigated using x-ray diffraction, electron microscopy, and magnetic measurements. The mechanical alloying of Sm2O3 with Co and Ca resulted in the formation of CaO and an amorphous Sm-Co phase. The SmCo5 phase formed durin…
Cathodoluminescence (CL) measurements made on natural zircon crystals are reported for the temperature range 45-300 K. Different combinations of excitation conditions used at various temperatures, coupled with information on the decay lifetimes of the emission features provided by modulation of the electron beam, enab…
The growth rate of diamond synthesized in an oxygen-acetylene flame has been measured in situ with an infrared pyrometer. During the growth, the sample’s emitted radiation intensity is modulated in time by interference phenomena in the growing diamond film, causing a periodic variation of the pyrometer’s apparent temp…
We demonstrate that ferroelectric liquid crystals are suitable for application in polymer-dispersed liquid crystal (PDLC) displays. The alignment of the liquid crystal can be controlled by mechanical shear during the polymerization-induced phase separation between the liquid crystal and the UV-curable adhesive which f…
Epitaxial MgO thin films were grown on (100) GaAs substrates by reactive rf magnetron sputtering. Coupled x-ray diffraction, off-axis φ scan, and transmission electron microscopy indicated in-plane alignment of the MgO film with the GaAs substrate such that MgO[100]∥GaAs[100]. PbTiO3 ferroelectric thin films, grown on…
Amorphous-to-crystalline and crystalline-to-amorphous transformations are triggered in GeSb thin films by irradiation with femtosecond and picosecond laser pulses. Phase changes are accompanied with optical contrast and therefore the feasibility of phase-change optical recording at ultrafast rates is demonstrated for…
The origin of strain-induced, modulated domain structures observed in epitaxial ferroelectric lead titanate thin films is discussed using a phenomenological total-energy calculation. Linear elasticity is used to account for the substrate contribution while a free-energy functional of the Landau-Ginzburg-Devonshire typ…
Small colloidal particulates (150 nm and below, in diameter) can be redirected specifically to the rabbit bone marrow following intravenous administration by coating their surface with the block co-polymer poloxamer-407, a non-ionic surfactant. The coated colloids are sequestered by the sinusoidal endothelial cells of…
Cathodoluminescence spectra of undoped and boron-doped diamond films are reported and are compared with each other. The dominant spectra feature of these samples is the broad luminescence bands centered around 2.83 and 2.32 eV in undoped and relatively heavily doped samples, respectively. Our result indicates that the…
Binary mixtures of suspended hard-sphere colloidal particles, radius ratio ${\mathit{R}}_{\mathit{B}}$/${\mathit{R}}_{\mathit{A}}$=0.58, were observed to undergo entropically driven freezing transitions into both the ${\mathit{AB}}_{2}$ and the ${\mathit{AB}}_{13}$ superlattice structures at different relative proport…
A new dispersion involving a polymer in low concentration with a cholesteric liquid crystal is reported. Two types of light modulators from these materials are described as a normal mode shutter which is opaque (light scattering) in the field-OFF state and transparent in the field-ON state and a reverse-mode shutter w…
The Zeeman tensor g and the 51V hyperfine tensor A of the metastable spin triplet state of the VO3- 4 ion are determined by optically detected magnetic resonance experiments. The experimental values of the elements of these tensors are compared with theoretical predictions made with the aid of perturbation theory. The…
The electronic structure of the lowest excited triplet state of the vanadate ion is investigated by determining the polarization of the emission from the individual spin sublevels with optically detected magnetic resonance techniques in zero field at 1·3 K. In addition, the polarization of the total emission is determ…
A packed column approach was used in this investigation to determine pore volume and surface area distributions of several celluloses. Specific surface areas for Avicel PH 102, Solka Floc BW 300, and two size fractions of corn cobs that have been pretreated to remove lignin and hemicellulose were measured using this t…
Mie theory and geometrical-optics ray tracing are used to obtain the distribution of electric energy density inside a nonabsorbing micrometer-sized sphere illuminated by a polarized plane wave. The Mie solution shows the multiply reflected geometrical-optics rays inside a sphere having a diameter of ~ 150 free-space w…
Abstract Dielectric thin‐film guided mode scattering from a finite‐element periodic grating of circular wires or circularly curved metal strips is considered. An accurate solution method is developed and results of computations for the H case are given. © 1992 John Wiley & Sons, Inc.
Scanning tunneling microscopy (STM) and point-probe electrical conductivity measurements of electrochemically protonated films of the emeraldine-base form of the conducting polymer, polyaniline are reported. The conductivity varies spatially, dependent on the size (L(M) \m=~\ 200 to 300 angstroms) of granular metallic…
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Conjugated polymers offer, in principle, the combination of polymer processibility together with interesting electronic properties. The feasibility of controlling materials to give structures with well-defined properties has provided an important focus for the experimental work. A decade or so since the first work on…