Materials Literature
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The electrical properties of single crystals of yttria-stabilized zirconia [${(\mathrm{Z}\mathrm{r}{\mathrm{O}}_{2})}_{0.88}$-${({\mathrm{Y}}_{2}{\mathrm{O}}_{3})}_{0.12}$], known to be an essentially anionic conductor, are studied in wide ranges of temperature (400-1100 K) and frequency (1.6 Hz-100 kHz). The dc elect…
Surface optical phonons have been detected on both the polar (100) and nonpolar (110) faces of GaAs, InP, and GaP with the use of high-resolution electron-energy-loss spectroscopy. The observed frequencies (GaAs: 291, InP: 337, GaP: 396 ${\mathrm{cm}}^{\ensuremath{-}1}$) on all surfaces are in excellent agreement (wit…
Abstract Um Einblick in die Bildungstendenz der Porphyrine zu gewinnen, wurde die säurekatalysierte Kondensation linearer Oligopyrrole 12a–d , 18 und 19 in verschiedenen Kombinationen untersucht. Obwohl hierbei im Prinzip die Bildung cyclischer Tetra‐, Penta‐, Hexa‐ und Heptapyrrole möglich wäre, erfolgte in jedem Fal…
Site selective spectroscopy has been performed for CaF2:Eu3+ samples as a function of annealing temperature and dopant concentration. The Eu3+ lines have been classified into five sites, two of which correspond with Eu3+ clusters. High annealing temperatures dissociate the clusters and leave Eu3+ ions in cubic and tet…
We extend the generalized van der Waals theory to the case of aligned nematic liquids which are subjected to curvature (i.e., “splay’’, “twist’’, and “bend’’) deformations. The Helmholtz free energy is written as an explicit functional of both the orientational distribution f(Ω) and the spatial variation n̂(R) of the…
We report photoemission spectra and intensity profiles of the $3d$ emission and the resonant valence-band satellites in Cu, ${\mathrm{Cu}}_{2}$O, and CuO. By analyzing the satellite separation energies, the multiplet structure, and the resonance shifts, we show that alternative resonance mechanisms are observed on Cu…
Detailed quantitative studies of the visible near-ir absorption spectra of trans-${(\mathrm{CH})}_{x}$ have been carried out in the semiconducting, transitional, and metallic regimes. With the use of the opto-electrochemical technique to take advantage of the control and precision of electrochemical doping, the absorp…
The following new phenomena recently brought to light by the Lorenz–Mie theory of scattering of electromagnetic radiation by spheres are reviewed: invisible particles, negative absorption, photophoresis, anisotropic photoelectron emission, Raman and fluorescent scattering by molecules embedded in dielectric spheres, e…
The electrical resistivity of pure hexagonal boron nitride in the c direction was measured from 700 degrees C to 1400 degrees C. Special attention was paid to allowance for electrical leakage of the measurement rig. The logarithm of the resistivity increased linearly with the reciprocal of absolute temperature, sugges…
Abstract A new method based on the inversion of a relation derived by Krathy, and thereby allowing the determination of the orientation distribution function of amorphous polymers by Wide Angle X‐Ray Scattering (WAXS), is described. With a simple approximation, in many cases disturbing intramolecular scattering can be…
Oscillations of the steady-state rate of catalytic CO oxidation on clean Pt surfaces were observed under low-pressure conditions and are related to the adsorption properties of the reactants. Evidence is presented for a model in which the reversible (5\ifmmode\times\else\texttimes\fi{}20)\ensuremath{\rightleftarrows}(…
The basic theoretical considerations involved in developing instruments for electron spectroscopy for atoms and solids are discussed. To be competitive with x-ray emission or absorption spectroscopy methods, electron spectroscopy would have to achieve such high resolution that well-defined electron lines would be obta…
Abstract The mechanical properties (the moduli and collapse strengths) of three dimensional cellular solids or foams are related to the properties of the cell wall, and to the cell geometry. The results of the analyses give a good description of a large body of data for polymeric foams.
Various para substituted poly-N-arylpyrrole polymer films were prepared and their electrochemical properties were measured. Of particular interest are the poly-N-p-nitrophenylpyrrole films which can be oxidized to produce the polypyrrole cation and reduced to produce the nitrophenyl anion. The polymer films can be rep…
A new method for accurate measurement of penetration depth ( R ) of electrons with various energies in materials was examined, using an irradiation effect in both aluminum and LiF crystals. The results obtained are summarized as follows: a) The value of R markedly decreases with the increasing energy of electrons used…
A critical assessment of the extensive data from published direct measurements of the permeability or permeation constant of hydrogen and its isotopes in iron, iron-base alloys, stainless and ferritic steels is presented.
Summary Authigenic albite occurring as euhedral overgrowths up to 400 μm in size is a characteristic feature of the Pendleside Limestone in the Craven Basin of northern England. The albite is very pure, low-albite in keeping with other authigenic albites in carbonate rocks. The detrital cores of the albites are angula…
Glow curve shape and thermoluminescence (TL) sensitivity in LiF:Mg,Ti single crystals have been studied as a function of Mg2+ and Ti3+ concentrations. A detailed method for TL optimization is presented, along with a simplified scheme which relies on the ratio of peak 5 height to peak 4 height (or ratio of peak 5 to pe…
Abstract N,N′-Bis(1-methyl-3-oxobutylidene)ethylenediaminato-1,3-di-4-pyridylpropaneiron(III) tetraphenylborate was synthesized and the temperature dependences of the Mössbauer spectrum and magnetic susceptibility for the compound were measured. The fact that the electronic relaxation between 6A1 and 2T2 states is fas…
Abstract Expansion of the porphyrin π-system by peripheral substitution lowers the oxidation potential of the macrocycle and increases the photocurrent quantum yield obtained when the porphyrin is used as sensitizer in a photocell. Tetrabenzporphyrins fall among the most efficient porphyrin sensitizers studied so far…