Materials Literature
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The self-consistent charge distribution in covalently bonded crystals and molecules is divided into two components, an atomic and a bonding part. Both can be calculated in elemental crystals from macroscopic dielectric properties. The theory is easily generalized to treat heteropolar and anisotropic effects, lattice v…
Numerous grains of gibbsite surrounded by zones of chlorite were found in six samples of sediment taken from Waimea Bay off the coast of Kauai, Hawaii. The chlorite has formed from the gibbsite, and growth bands in the chlorite either are parallel to chlorite-gibbsite interfaces or are concentric around small remnants…
Mössbauer spectroscopy has been used to investigate the early stages of phase separation in the Cu–Ni.7Fe.3 pseudobinary system. Our results indicate that new phase of composition close to the equilibrium composition is formed early in the decomposition, and grows in amount during transformation. The type of compositi…
The Seebeck coefficient, α, of semiconducting glasses based on vanadium pentoxide can be calculated from a knowledge of the concentration ratio of the high and low valence ions. The concentration of vanadium ions in the glass and long-range order apparently have no effect on α. Semiconducting glasses based on iron oxi…
Reflectance measurements for Ge films evaporated in situ are reported for 16 wavelengths between 490 and 1610 \AA{}, corresponding to photon energies of 25.2 and 7.7 eV. Measurements were taken after 3-min exposures to ambient pressures of 5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}7}$ Torr. Reflectance v…
The crystal structure of 16(CH3)3CNH2·156H2O has been determined from three-dimensional x-ray-diffraction data obtained at −30°C. The crystals are cubic, space group I4̄3d, with cell dimensions a=18.81±0.02 Å. The host framework of hydrogen-bonded water molecules consists of face-sharing heptakaidecahedra which have t…
Results of numerical calculations of energy transport in one- and two-dimensional lattice models are reported. Nearest-neighbor harmonic or anharmonic forces were used in randomly disordered mixtures of two different atomic masses. Opposite ends of the lattices were in contact with thermal reservoirs, which transfer e…
The role of the electronic properties of a semiconductor in heterogeneous catalysis and electrochemistry was experimentally investigated on single-crystal ZnO. It was shown quantitatively that the availability of electrons and holes at the surface is dominant in the mechanism of a heterogeneously catalyzed reaction. C…
A vibrational and attendant conformational analysis of the liquid n-paraffins and molten polyethylene is presented. For the purposes of the analysis a valence force field was derived which is applicable to both planar and nonplanar chains. The force field was evaluated from observed frequencies of trans (T) and gauche…
The Raman spectrum of crystalline quartz has been studied at temperatures between -196 and 615\ifmmode^\circ\else\textdegree\fi{}C. A weak mode of symmetry ${A}_{1}$ with room-temperature Raman shift of 147 ${\mathrm{cm}}^{\ensuremath{-}1}$ is found to grow in intensity and move towards zero Raman shift as the alpha-b…
The structure of Ca${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$ has orthorhombic symmetry (space group ${{D}_{2h}}^{16}\ensuremath{-}Pnam$) and is characterized by Fe-O-Fe-O chains within which the Fe-O-Fe bond angle is \ensuremath{\sim}130\ifmmode^\circ\else\textdegree\fi{}. These chains are cross-linked by means of Fe-O-Fe…
The first appreciable decrease in the lifetime of the $^{2}E$ state of ${\mathrm{Cr}}^{3+}$ in ruby and emerald as the temperature is raised is shown to be the result of populating the shorter-lived $^{4}T_{2}$ level in thermal equilibrium with the metastable $^{2}E$. The direct transition from the $^{4}T_{2}$ to the…
The intensity of triplet-exciton annihilation luminescence in anthracene crystals at room temperature increases in weak magnetic fields up to a maximum increase of 5% at 350 Oe. For stronger fields the intensity decreases, finally leveling off at 80% of the zero-field value for $H\ensuremath{\gtrsim}5$ kOe. Sharp dips…
The effects of thermal-neutron irradiation on the parameters involved in the thermoelectric figures of merit of Bi 2 Te 3 and its thermoelectric alloys have been examined. It was found that integrated fluxes of up to 2 × 10 18 neutrons/cm 2 are not sufficiently high to affect the figures of merit of these materials by…
Abstract 2,4‐ O ‐Benzylidene‐1,6‐dithiol‐D‐glucitol is prepared by nucleophilic displacement of tosyloxy groups from 3,5‐di‐ O ‐acetyl‐2,4‐ O ‐benzylidene‐1,6‐di‐ O ‐tosyl‐D‐glucitol with thioacetate in N , N ‐dimethylformamide and deacetylation of the product. Oxidative polymerization with oxygen and selenium dioxide…
Abstract Graft copolymerization of natural rubber and MMA was carried out in the presence of Bz 2 O 2 or AIBN as thermal initiator and hydrogen peroxide or benzophenone as photosensitizer. From the overall copolymerization product, the rubber–PMMA graft copolymer fraction was isolated from unreacted rubber and free PM…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdsorption of polymers at the solution-solid interface. III. Polyethers on nylonG. J. Howard and P. McConnellCite this: J. Phys. Chem. 1967, 71, 9, 2991–2995Publication Date (Print):August 1, 1967Publication History Published online1 May 2002Published inissue 1 August 1967ht…
Measurements using strain gauges of the magnetostriction constants of Yb3+ and Ce3+ ions in YIG are presented. The temperature dependence of the magnetostriction for Yb3+ in YIG is compared to theories by Callen and Callen based on crystal-field (single-ion) and anisotropic rare-earth-iron-exchange (two-ion) interacti…
Atactic polystyrene was hydrogenated under different conditions. At incomplete hydrogenation, a mixture of polystyrene and poly(vinyl cyclohexane) results. The glass temperatures were studied under different conditions by differential thermal analysis and found to be 100°C for polystyrene and 80°C for poly(vinyl cyclo…
The dynamic mechanical behavior of 60Co irradiated polytetrafluoroethylene (PTFE) has been investigated at audio frequencies over the approximate temperature range of 80 to 600†K for irradiation doses up to 200 Mrad. The data presented herein, together with data obtained during earlier studies of the effects of radiat…