Materials Literature
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Lithium-sodium beta alumina having a lithium/sodium ratio greater than about I appears to be the first generally useful lithium superionic conductor that has been reported. It exhibits strikingly nonlinear ion exchange properties and may presage the discovery of similar co-ionic interactions in other superionic conduc…
Afin d'étudier la précipitation du composé Fe3Ga ordonné (structure Ll2 ou DO19) dans une matrice elle-měme ordonnée (structure DO3), nous avons été conduits à préciser le diagramme de phases du système fer–gallium dans la région 15 è 30 %at Ga. La preéipitation se produit suivant un processus continu avec germination…
The Mössbauer effect of 57Fe is used to investigate the early stage of phase separation in the Fe-33 at% Cr-21.5 at% Co alloy, a new ductile permanent magnet. After being quenched from a one-phase region, the foil samples are aged at 560 °C, and the Mössbauer spectra are taken at room temperature. The hyperfine field…
Les propriétés magnétiques du composé CaCu3Ti4O12 (groupe d'espace Im3) ont été étudiées sur un échantillon polycristallin par mesures de susceptibilité magnétique et par diffraction neutronique. A basse température, une configuration de spins antiferromagnétique s'établit au-dessous de TN = 27 K; à 2,5 K les moments…
Single crystals of CaYAlO4 doped with Nd3± and Er3± are grown by optical zone melting method. At 77 and 300 K the absorption and luminescence spectra of Nd3± and Er3± ions are investigated in detail. Characteristic broad line widths of the luminescence and absorption are found which remain unchanged by rising the temp…
The characteristic luminescence of the tungstate group in the system Ba2CaTe1-xWxO6 is shown to consist of two emission bands. On basis of a discussion of the excited state of the tungstate group these emission bands are assigned to spin-forbidden transitions. Within the tungstate group the radiationless relaxation ra…
A field theory for the magnetostatic surface wave (MSSW) reflectivity of a single shallow groove etched on top of an epitaxial YIG film is presented. Computed reflection characteristics are obtained for the case in which the surface of the YIG film is metallized after the groove is etched. It is found that the MSSW re…
A new reflective dichroic display device is described. The only components include a quarter-wave retarder positioned between an aligned dichroic nematic liquid-crystal display cell and a diffuse metallic reflector. This configuration allows both polarizations of incident light to be absorbed without affecting the pol…
Recent de Haas-van Alphen measurements on $2H$-Ta${\mathrm{Se}}_{2}$ in the $3{a}_{0}$ commensurate phase have, through their analysis, promoted a reexamination of the charge-density waves and periodic structural distortion developed in the $2H$ family of transition-metal layer dischalcogenides.
The diffraction of electromagnetic waves from the rough surface of a material of finite permittivity is examined for the case where the wavelength of the incident radiation is comparable to the dimensions of the surface roughness. Two methods of calculation studied are the Rayleigh method and the extinction-theorem in…
The interaction rate of four-phonon processes at high temperatures is derived in terms of the Gr\"uneisen constant and its dilational derivative. The interaction arises in part from quartic anharmonicities and in part from cubic anharmonicities to second order. The four-phonon relaxation rate varies as the square of t…
In this paper we present a theoretical study of the optical and microwave properties of microscopically inhomogeneous disordered materials. We derive an effective-medium theory (EMT) for the propagation of light in a heterogeneous system by means of a self-consistent extension of a multiple-scattering model. This appr…
The magnetically induced circular-polarized emission associated with the vibrational sideband of the 2 E g to 4 A 2g transition of V 2+ and Cr 3+ ions at sites of cubic symmetry in MgO is reported. The Zeeman selection rules are derived and used to obtain a measure of the relative strength of the coupled T 1u and T 2u…
A new effect is reported: weak ferromagnetism induced in a ferroelectric antiferromagnet (BaMnF 4 ) by means of a linear magnetoelectric interaction. The direction and magnitude of spin canting in BaMnF 4 are calculated and found to be in agreement with experiment.
I present a theory of the electron energy-loss spectra observed in x-ray photoemission from the core levels of solids and report on calculations for the $2s$ and $2p$ core levels of Al, Mg, and Na. The calculation takes intrinsic as well as extrinsic plasmons into account, and in all cases the agreement between theory…
Catalytic reactions of carbon monoxide with hydrogen have been studied in which intermetallic compounds of the formula MNi(5) (where M is thorium, uranium, or zirconium) have been used as the catalysts. The materials perform effectively as methanation catalysts; ThNi(5) has a specific activity exceeding that of a typi…
The semiconductor liquid junction cell n-GaAs/0.8M K(2)Se-0.1M K(2)Se(2)-1M KOH/C has been shown to attain 9 percent photovoltaic power conversion efficiency in sunlight. Accelerated tests under 3100 degrees K light sources of several solar intensities indicate very low photocorrosion currents and high output stabilit…
Übersichtsbericht zur Beurteilung der Eignung von feuerfesten Oxiden, Mischoxiden und Oxidverbindungen als Festelektrolyte zur Sauerstoffmessung in Stahlschmelzen. Zusammenstellung und kritische Bewertung der elektrischen Eigenschaften der in Frage kommenden oxidkeramischen Festelektrolyte.
The crystal structure of a mineral with the stoichiometry (K0.58Ba0.36)2(Ti0.93FeIII0.06)6O13 has been determined by X-ray diffraction and refined by full-matrix least squares to a residual of 0.076 for 1688 ?observed? reflections. Crystals are monoclinic, C2/m, a = 15.453(2), b = 3.8368(7), c = 9.123(2) ?,ß = 99.25(1…
Abstract Crystallographic properties of illite and chemical properties of organic matter in various mudstones ranging in age from Archean to Miocene were investigated. The breadth of the (001) X-ray powder diffraction peak of illite correlates significantly with the ratio of aliphatic to condensed-aromatic components…