Materials Literature
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We present evidence that in carbon-polyvinylchloride composites, consisting of aggregates of carbon spheres (100-400 \AA{}) dispersed in the insulating matrix, the electrical conductivity can be ascribed to a novel mechanism of tunneling with potential-barrier modulation by thermal fluctuations. Theoretical considerat…
A systematic compilation of chemical thermodynamic and elementary reaction rate data has been carried out, using information obtained from literature searches and chemical kinetic modeling. These data are presented in a flexible and convenient form for use in computer programs which require such input data.
For pt.I see ibid., vol.11, p.1523 (1978). A set of interionic potentials of the Born-Mayer form is derived for the alkali halides. The specification is completely in terms of parameters of two types, (a) parameters which relate to the constituent ions and (b) parameters which apply to all crystals. Thus the parametri…
Room temperature measurements of the phonon dispersion relations in ferroelectric lithium niobate have been carried out by inelastic neutron scattering. Most of the measurements were made along the c* direction with two acoustic branches measured along an a* direction. The q to 0 slopes of the acoustic branches are fo…
A consistent set of shell parameters for alkali halide crystals of both rocksalt and CsCl structures is reported. The fitting procedure, values of the parameters and their sensitivity are discussed. Short range interionic potentials are determined and are shown to give a good description of both static and dynamic pro…
A study of variations of charging and discharging transients in low-density (0.918 gm cm -3 ) polyethylene has been made over a wide range of fields and temperature and a limited range of sample thickness and electrode materials. In the temperature range 113-273K two broad isochronal (i.e. current at constant time) pe…
A general description is given of the behavior of polymeric dielectrics in low fields, including polarisation and depolarisation, and transient and steady state conduction, in isothermal and non-isothermal conditions. An attempt is made to present a unified interpretation applicable to all of these phenomena.
Measurements are reported on the lateral motion of charges along thin films of polyethylene terephthalate (PET) in air at 40% humidity. A sensitive, high-resolution induction probe coupled to a computer is used to scan the sample in a raster mode. Thus it is possible to produce not only line scans of the charge distri…
Vacancy mutation by (about six) trapped helium atoms — as has been observed in molybdenum — reduces the vacancy concentration, at which interconnecting paths for the helium begin to form, from 16 to 10% in b.c.c. materials. This follows from percolation studies which include this mutation effect.
Structural phase transitions are investigated in crystals of the isostructural compounds MRA2 (M alkali metal, R trivalent metal, A anion (MoO4)2- or (WO4)2-). A group-theoretical analysis of possible transitions is carried out. It is shown that the transitions are of pure ferroelastic nature, occur between centrosymm…
Optical and EPR studies of K(H1−xDx)2PO4 (0⩽x⩽1) single crystals irradiated at 77°K with 60Co gamma rays and observed in liquid nitrogen, argon, and oxygen, have permitted not only the identification of two radical species produced as HPȮ−4 and H2PȮ4, but also a description of the annealing processes and their correla…
Condensation potentials and corresponding electrical currents are observed during the isothermal growth of amorphous, cubic, and hexagonal ice from the vapor phase. Upon heating of the condensate a thermally stimulated current (TSC) spectrum is observed with the application of any external electric field. Current peak…
Metal complexes of water-soluble and other porphyrins have been prepared by a heterogeneous reaction with the metal reactant present in an insoluble form. The oxidation state of the metal is important in the reactions. Metal reactants in the lower oxidation states (0, I, II) react with porphyrins but those in the high…
The generation of periodic surface corrugations by ion-beam milling and chemical etching of grating relief patterns in photoresist is analyzed. A general treatment is developed for gratings of any desired period on substrates of arbitrary reflectivity, but particular emphasis is given to the generation of gratings wit…
Effects due to overlap between orbitals on neighboring atoms and to next-nearest-neighbor interactions, on the electronic structure, are investigated. As an illustration of their importance, analytic results are obtained for the density of states of a Bethe lattice and numerical calculations are carried out to obtain…
Molecular dynamics calculations have been carried out to establish quantitative properties of the Gaussian core model near its crystal–fluid transition. Two densities have been considered, for both of which the stable crystal structure at absolute zero is body-centered cubic. Spontaneous melting and freezing events we…
The Hall mobility has been measured for the first time in a layer compound both along and perpendicular to the layers. The measurements have been extended as a function of temperature and of electrical field by a pulse technique. The results indicate that both mobilities are limited by homopolar optical-phonon scatter…
Th e effect of TiN p articles ill low carbon low allo)' steels 011 the austellite graill size was studied in relation to tlte dissolutioll , coalescence and reprecipitation.Nlain results were as follows.(I) Ostwald ripening was observed in the process of coalescence of TiN jJarticles.( 2) Thg main factors COli trollin…
Single crystals of NiPcI(1.0) (Pc = phthalocyanine), which are composed of one-dimensional stacks of (NiPc)(+0.33) molecules and chains of I(3)(-) molecules, exhibit metallic electrical conductivity in the stacking direction. At room temperature the mean free path of the carrier is 3.3 to 8.2 angstroms.
Photoemission studies combined with measurements of the magnetic susceptibility show that La segregates to the surface of La${\mathrm{Ni}}_{5}$ in the presence of ${\mathrm{O}}_{2}$ or ${\mathrm{H}}_{2}$O, and the Ni precipitations are formed during hydrogenation. This represents a self-restoring mechanism of the acti…