Materials Literature
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The broadband luminescence peaking at about 790 nm in a natural sample of sillimanite was investigated. The origin of luminescence is most likely Cr impurities. The temperature dependences of decay time, total intensity, and thermal broadening of emission line shapes were measured. Relatively long decay times at room…
High-temperature Raman-scattering measurements in anhydrous polycrystalline ${\mathrm{CaBr}}_{2}$ have revealed the occurrence of a structural phase transition at a temperature ${T}_{c}$ within the region 760--780 K. The variation of the Raman spectrum indicates that ${\mathrm{CaBr}}_{2}$ transforms from its room-temp…
The relaxation and interface quality of two representative molecular-beam-epitaxy-grown Si-Si1−xGex strained-layer superlattices have been investigated by Raman scattering spectroscopy, double-crystal x-ray diffraction, transmission electron microscopy, and charge collection microscopy in a scanning electron microscop…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical performance of crosslinked poly(styrene)-co-poly(vinylpyridine) composite electrodes containing carbon blackJongman. Park and Brenda R. ShawCite this: Anal. Chem. 1989, 61, 8, 848–852Publication Date (Print):April 15, 1989Publication History Published online1…
Tungsten oxide films (WO(3)) are deposited by thermal evaporation techniques using the starting materials of tungsten (W) and tungsten oxide (WO(3)). By varying deposition parameters, three main types of WO(3) film exhibiting different optical properties form. These are blue, gray, and colorless films. The samples are…
We discuss the characteristic solid-solution hardening and softening of Al-based fcc alloys using ab initio Korringa-Kohn-Rostoker augmented-spherical-wave electronic structure calculations. We choose the dilute Al-X alloy systems, X being Li, Be, Na, Mg, Ca, and Cu, which exhibit characteristic solid-solution hardeni…
We have discussed a valence-electron energy-loss spectrum measured in reflection geometry using a cylindrical mirror analyzer (CMA) and derived the angular distribution of inelastic scattering, the momentum transfer, and the differential cross section per unit energy. If a critical inelastic-scattering angle is smalle…
Below a temperature TB, the rotational relaxation of small molecules in supercooled liquids appears to bifurcate into slow α and faster β relaxations. The characteristic time for the former diverges in Vogel–Fulcher fashion at the glass transition Tg and that of the latter follows Arrhenius behavior from above TB to b…
We have used a one-dimensional kinetic analysis to model the gas-phase chemistry that occurred during the diamond growth experiments of Chauhan, Angus, and Gardner [J. Appl. Phys. 47, 4746 (1976)]. In those experiments the weight of diamond seed crystals heated by lamps in a CH4/H2 environment was monitored by a micro…
Hydrogen was found to alter the electrical properties of gold (Au), titanium (Ti), and tungsten (W) thin films deposited on SiO2/Si substrates. Specifically, the addition of H2 was found to reduce both hillock growth and the rate of electromigration in Au and Ti films. The resistance and 1/f noise of unpassivated Au,…
We have determined the surface-plasmon modes of cylindrical pores in metals and of pairs of coupled cylindrical pores having parallel axes. The eigenfrequencies and the polarization fields are determined in the case of interacting pores of equal radii where the modes are even or odd with respect to the symmetry plane.…
The onset of rigidity in ${\mathrm{Se}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Ge}}_{\mathrm{x}}$ glasses is probed by room-temperature longitudinal and transverse elastic moduli determined by ultrasonic measurements. The longitudinal modulus displays linear behavior with increasing x up to x=0.3, correspondin…
The energy transfer between the ${\mathrm{Mn}}^{2+}$ ions and free electrons and electrons bound on shallow donors in ${\mathrm{CdF}}_{2}$:Mn,Y crystals has been examined. This so-called Auger effect on localized impurities turned out to be a very efficient quenching mechanism of the deep luminescent centers in semico…
The temperature dependence of the dc and ac conductivities has been studied in sputtered amorphous carbon films. The dc conductivity is proportional to ${T}^{n}$ with n=15--17 below room temperature. The mechanism is discussed in terms of the mobility-edge conduction, variable-range hopping, and small-polaron hopping.…
The static properties of a polymer molecule in a porous medium are investigated. The porous medium is simulated using a site percolation model in which the various sites are occupied (or unoccupied) randomly. A freely jointed chain is allowed to move in continuous space between the obstacles. Effects of excluded volum…
Standard microcanonical rate-constant theory can be cast in a form which closely resembles and, in the case of a sufficiently large medium, reduces to that of the canonical ensemble. This relation permits a new understanding of the role of an activation energy in a chemical reaction. A facile methodology is also propo…
The quasiparticle excitation spectrum is calculated for the nearly-free-electron metals Li, Na, and Al by evaluation of the electron self-energy operator within the GW approximation and a generalized plasmon-pole model. The calculated quasiparticle energies for Na and Al are in excellent agreement with angle-resolved…
Multiple-scattering effects of electrons traveling along atomic chains are shown to be important and useful for surface structure determination, especially in the medium-energy range (200--1000 eV). This applies to techniques based on diffraction of elastic electrons, such as medium-energy electron diffraction, as wel…
The unfavorable effect of La on the magnetic properties of R-Fe-B permanent magnets is shown to be related closely to remarkable changes in microstructure due to excessive oxidation of La-containing R-rich phases in the alloys. Ce and Al are found to be effective in promoting the sintering process of La-containing all…
A thermodynamic theory is presented to model the phase transitions and properties of lead zirconate. The free energy ΔG is expressed as a power series in terms of the ferroelectric polarization (Pi=Pai+Pbi) and antiferroelectric polarization (pi=Pai−Pbi) including all possible terms up to the sixth power, but only fir…