Materials Literature
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The cathodoluminescence from Eu 3+ and Tb 3+ in the orthoborates of In, Sc, Y, La, Gd, and Lu is examined. The host is shown to be particularly effective for both activators. Observed spectral details of the luminescence are related to effects of crystal symmetry on electronic transitions.
The equilibrium oxygen pressure for the reaction was accurately measured over the temperature range 910°–1145°K. The following working equation for the oxygen pressure is valid over the experimental range. The following expressions, valid from 298°–1200°K, apply to the formation of one mole of The heat of formation an…
Infrared and Raman spectra are reported for tin(IV) nitrate, titanium(IV) nitrate, and vanadium(V) oxide trinitrate. The spectra are consistent with bidentate co-ordination of all nitrato-groups in each case and assignments are suggested for the bands on this basis. Coupling of the vibrations of individual nitrato-gro…
Introduction. The distribution of stress produced in the interior of an infinite elastic solid when a constant pressure is applied over the entire surface of a penny-shaped crack has been solved by Sneddon(6), (7). The problem considered here is the closely allied one of a plane longitudinal wave, harmonic in time, mo…
Abstract The values of Δε and σ 0 in the expression σ = σ 0 exp {−Δε/ 2kT } for the dark conductivity σ, tend to increase together over the whole range of organic semiconductors. They fall into a broad band of values confined roughly between two lines given by log σ 0 = αΔε + β, the compensation rule, with log σ 0 var…
Abstract Studies of single‐crystal deformation explain the small‐ and wide‐angle x‐ray observations of the cold drawing of PE, particularly the effects in the necking zone where the original spherulitic structure is transformed into a highly aligned fiber structure. Whole blocks of folded chains are broken out of the…
Abstract The crystallization kinetics and morphology of poly(tetramethyl‐ p ‐silphenylene)siloxane spherulites have been investigated over a temperature range of 25–130°C. The effect of molecular weight on the spherulitic growth rates, ranging from the monomer to molecular weights about 10 6 , is discussed in terms of…
Electrical conductivity and emf measurements on polycrystalline , as functions of the partial pressure of oxygen, at temperatures ranging between 800° and 1100°C, are used to study some transport and thermodynamic properties of nearly stoichiometric and nonstoichiometric . Due to the localized character of electrons i…
Abstract The scattering of electron waves by an amorphous material is partly dependent on its structure. The variation of this scattered intensity with angle may be mathematically transformed to give a radial distribution function (r.d.f.) which describes both the position and co‐ordination of sets of atoms. The metho…
The mechanism of dehydrogenation of formic acid over zinc oxide and magesium oxide was studied by adsorption measurements and the infra-red technique during the course of the decomposition. The acid was absorbed into the bulk of the oxides to form metal formate and water, and the subsequent decomposition proceeds over…
Dislocations in single crystals of melt-grown, solution-grown and vapour-grown anthracene have been characterized using the etch-pit technique and from an analysis of cleavage patterns. From the observed alignments of emergent dislocations (at (00l) faces) to form small-angle boundaries (of twist, tilt and mixed chara…
Through the use of deuterated samples of Ni ( OH ) 2 electrodes at various stages of charge, it has been possible to make definitive band assignments for the structures of the active material. The relative intensity of the band due to hydrogen bonding in the charged state is shown to be a measure of the electrochemica…
The dielectric constants and losses of anisole, bromocyclohexane, aniline, N,N-dimethylaniline, and cyclohexanol in the pure liquid state have been measured at 2.2 mm wavelength at temperatures between 20° and 60° and combined with data in the literature to calculate the dielectric relaxation times. Where additional d…
Hall effect, conductivity and Seebeck measurements have been made on a series of NiO and CoO crystals containing up to approximately 0.6 at.% Li in the range 150-1100 °K. The results are interpreted in terms of 3d conduction in a narrow band and indicate that impurity conduction is dominant in many samples up to 200-3…
Heat-capacity measurements have been made on UP and UP1.35 from 11 to 320°K and values of the standard thermodynamic functions are tabulated. The Cp curve for UP shows a pronounced, sharp anomaly at 22.5°K and also an expected anomaly at 121°K, which corresponds to antiferro-magnetic ordering of the unpaired electrons…
Abstract Solid solutions with the general formula Bi 1– x Ca x MnO 3 (0.2 ≦ x ≦ 1) are found to possess the perovskite structure. The phase diagram based on X‐ray diffraction studies involving cubic, orthorhombic and monoclinic modifications is constructed. It is concluded from conductivity and X‐ray data that the tra…
The heats of reaction of arsenic with fifteen group 3A metals have been measured by means of dynamic differential calorimetry. The heats of formation obtained at the reaction temperatures, in kcal/mole, are as follows: ScAs, –65.2 ± 6.0; YAs, –77.4 ± 3.4; LaAs, –73.0 ± 4.5; CeAs, –68.9 ± 3.0; PrAs, –73.4 ± 3.1; NdAs,…
Stress corrosion cracking of titanium: 8% Al‐1% Mo‐1% V alloy notched tensile specimens was investigated in various salt solutions under potentiostatic conditions. Stress corrosion cracking of duplex annealed Ti: 8‐1‐1 alloy occurred in chloride, bromide, and iodide solutions, but did not occur in other solutions such…
Abstract The preparation and properties of aliphatic and aromatic polyimides are reviewed. The discussion includes a comparison of methods of synthesis of the aliphatic vs. aromatic polymers and a detailed consideration of chemical structure vs. properties. The discussion of properties includes, in addition to propert…
The structures of cytochalasins A and B, metabolites of Helminthosporium dematioideum showing novel effects on mammalian cells, have been determined. Cytochalasin B is identical with phomin. (–)-α-Methyladipic acid is shown to have the R-configuration contrary to a previous assignment; the absolute configurations of t…