Materials Literature
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The magnetic interaction between local magnetic moments in an insulator or a semiconductor host is theoretically studied. For a dilute concentration of magnetic ions, the dominant mechanism for magnetic interaction could be the exchange polarization of the valence-band electrons of the host lattice. Its properties are…
Results are described for the field and temperature dependences of the electrical resistivity, Hall effect, and transverse magnetoresistance of ferromagnetic, antiferromagnetic, and diamagnetic Heusler alloys. The experiments cover the approximate ranges 2-300 K and 0-4.8\ifmmode\times\else\texttimes\fi{}${10}^{6}$ ${…
The theory of surface-enhanced second-harmonic generation at a metallic grating is developed. Using the form of the nonlinear source polarization given by Bloembergen et al. [Phys. Rev. 174, 813 (1968)], we solve Maxwell's equations to obtain the fields at the second-harmonic frequency. The calculations are done up to…
Abstract Crosslinking efficiency of isotactic polypropylene was studied as a function of the initiator used and of the reaction temperature. The decomposition rate of the initiator was found to be of prime importance for attaining the gel point. The over‐all efficiency of the process is strongly influenced also by the…
We report studies of sputtered iridium oxide films (SIROF's) by differential thermal analysis, evolved-gas analysis, scanning electron microscopy, x-ray diffraction, and electrical-conductivity measurements. SIROF's undergo an irreversible exothermic transition at \ensuremath{\sim}300\ifmmode^\circ\else\textdegree\fi{…
The electrical properties of single crystals of yttria-stabilized zirconia [${(\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…