Materials Literature
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We present the results of a combined x-ray and neutron diffraction study of the temperature dependence of the "forbidden" (222) reflection in germanium. Integrated intensities were measured from room temperature to 850\ifmmode^\circ\else\textdegree\fi{}C with x rays and to 904\ifmmode^\circ\else\textdegree\fi{}C with…
The radiative lifetimes for a number of electronic states of the alkaline earth monohalide molecules MX, where M denotes Ca, Sr, or Ba and where X denotes F, Cl, Br, or I, have been determined directly from the rate of fluorescence decay with time using a pulsed dye laser as an excitation source. The measured lifetime…
The pressure-volume relationships for EuSe, EuS, YbSe, and YbS have been obtained from high-pressure x-ray-diffraction studies to nearly 300 kbar. Like EuTe, EuSe and EuS exhibit normal compression and undergo the NaCl-to-CsCl-type transition at about 145 and 215 kbar. The compression curves of YbSe and YbS are anomal…
A calculation of the diamagnetism of graphite including the effects of trigonal warping of the Fermi surfaces has been performed using Fukuyama's formulation of the diamagnetism of Bloch electrons. Inclusion of the trigonal warping increases the diamagnetism by about 13% at low temperatures and reduces it by about 1%…
The auxospore wall of Melosira nummuloides C. A. Agardh is composed of two distinct parts, an organic layer and a layer of siliceous scales. Similar scales are reported from other species of the genus and their mode of formation is described. The possible phylogenetic significance of the two wall layers is discussed w…
The heat capacity of amorphous germanium, measured between 2 and 30 K using a thermal-relaxation technique, is about 50% greater than that of crystalling germanium, but has a similar temperature dependence. We infer an amorphous phonon density of states at low frequencies given by the TA crystalline density of states,…
Comparison of ultraviolet-photoemission, valence-orbital spectra (as well as high-resolution, x-ray photoemission, N-core-level spectra) of TTF-TCNQ, neutral TCNQ, and ${\mathrm{K}}^{+}$ ${(\mathrm{TCNQ})}^{\ensuremath{-}}$ indicates a large amount of charge transfer in TTF-TCNQ. The spectra for this complex show stro…
The effect of pressure on the lattice parameter of magnetite has been determined at room temperature up to 320 kbar by means of X ray diffraction employing a diamond anvil high-pressure cell. By using the Birch-Murnaghan equation with a (∂KT/∂P)T∣P=0 value of 4 ± 0.4 the isothermal bulk modulus at zero pressure was ca…
The high-field electrical properties of several groups of transition-metal phosphate glasses have been examined, especially those based on V, Fe, Cu and Mo ions, and pure and doped tungstates. Conductivity measurements have been carried out under DC and pulse conditions at fields up to approximately 10 6 V cm -1 but b…
Photoemission energy distributions for $20<~h\ensuremath{\nu}<~50$eV for semiconducting Fe${\mathrm{S}}_{2}$ (fool's gold) show a narrow, \ensuremath{\sim}1 eV wide, localized uppermost valence level, whereas the corresponding levels of semiconducting Ni${\mathrm{S}}_{2}$ are broad (\ensuremath{\sim}3.5 eV) and…
The structure of the hexamethylenetetramine 14N nuclear quadrupole resonance line has been studied in detail on a powdered sample at 77°K. An improved, frequency-stabilized spectrometer, interfaced to a digital computer, was used in resolving fine details of the experimental lineshape. The line shape could be fitted b…
The complete ligand-field, Coulomb interelectronic repulsion, and spin-orbit interaction matrices have been derived for the d 5 electron configuration within octahedral (O h ) and tetrahedral (T d ) symmetry. The calculations were performed in both the weak-field and strong-field coupling schemes and complete agreemen…
The electron beam retarding potential technique was used in a display-type Varian LEED-Auger apparatus to determine work function changes on contact materials Pd, Au, Ag and Pd-Ag 40 at.% (atomic percent). Surface compositional changes were created by heating and argon ion bombardment treatments and monitored by Auger…
Iron glaebules occur extensively in tropical and subtropical soils, therefore, glaebules were collected from a plinthic soil (Plinthic Paleudults) of the Southern Coastal Plain of the United States for classification and to determine their chemical and mineral composition. Glaebules were classified into four categorie…
Summary Vincentite, a new palladium mineral containing As, Sb, and Te, has been discovered in platinum-gold concentrates from the Riam Kanan River, SE. Borneo. It occurs as small grains (up to 40 µm) in iron-bearing platinum. In reflected light, vincentite is light brownish-grey and in some sections weakly anisotropic…
A simplified kinetic model describing the mechanism of pilling is proposed. This model involves only three parameters, which relate to the main stages of the process: the total number of pills, the rate of pill formation, and the rate of pill wear-off. These parameters can easily be calculated from the pill curve of t…
Abstract The thermal decomposition of [Ni(N2H4)6]X2 (X=Cl, Br, I) in solid phase was investigated by means of derivatography and IR spectral measurement. It was found from the derivatography that the decomposition of the chloride and bromide proceeded via tris-, bis-, and mono-hydrazine complexes as metastable reactio…
This paper considers the physical processes which may occur when a liquid weld metal drop comes in contact with a liquid metal pool. Experiments with drops of aqueous KCl solutions and mercury, combined with a theoretical analysis of the effects of surface tension and Lorentz forces, lead to the following conclusions.…
A torsion-balance apparatus, incorporating a photopotentiometer device and developed to study the torsional-hysteresis and torque-relaxation behaviour of both monofilament and multifilament yarns under conditions of constant tension, is described. Differences in the shape of the torsional-hysteresis curves are studied…
The rate of degradation by ultrasonation of polystyrene in tetrahydrofuran solutions has been measured at various concentrations, temperatures, and irradiation intensities. As reported earlier, the course of the changes in molecular weight distributions is independent of the molecular weight (MW) of the initial polyme…