Showing papers on "Conductivity published in 1973"

Conduction Characteristics of the Lithium Iodide‐Aluminum Oxide Solid Electrolytes

Abstract: The conduction characteristics of the polycrystalline lithium iodide containing aluminum oxide were studied. It was found that the incorporation of aluminum oxide substantially increased the conductivity of lithium iodide. Lithium iodide containing 33–45 mole per cent (m/o) aluminum oxide exhibited conductivities in the order of 10−5 ohm−1 cm−1 at 25° ± 2°C. Inasmuch as no substantial amount of aluminum oxide was found soluble in the lithium iodide under the experimental conditions, the increase in conductivity could not be explained by the classical doping mechanism. The electronic conductivity of the lithium iodide‐aluminum oxide solid was negligible compared to the ionic conductivity. Therefore, it is suitable as a solid electrolyte in solid‐state battery systems.

Thermal Conductivity of Complex Dielectric Crystals

Abstract: The theory of the thermal resistivity of dielectric crystals at ordinary and high temperatures in terms of anharmonic three-phonon interactions is reformulated. The resistivity is similar in form to that obtained by Leibfried and Schl\"omann, but larger by a factor of 6.8. The theory is then extended to crystals where the unit cell contains many atoms. To include all three-phonon interactions one sums over all harmonics of the reciprocal-lattice vectors in an extended-zone representation. This sum increases the scattering rate. However, the matrix elements of the three-phonon processes are reduced in the case of large unit cells, because coherence is lost in the Fourier transform of the different bonds in each cell. A simplified model is chosen, and in this case the latter effect cancels the former, so that the anharmonic relaxation rate is substantially independent of the number of atoms per unit cell. However, the zone boundaries affect the phonon dispersion curves and reduce the group velocity of most modes. Using a model proposed by Slack, in which only the acoustic phonons of the fundamental zone contribute to the conductivity, and invoking the independence of the relaxation time with cell size here derived, the conductivity varies as the inverse cube root of the number of atoms per cell. The conductivity varies inversely with temperature, even if the phonon mean free path is shorter than the cell dimensions, because the major contribution to the anharmonic interaction comes from the highest harmonics of the fundamental reciprocal-lattice vectors.

Electrical Conduction and Phase Transition of Copper Sulfides

Abstract: Electrical conductivity measurements have been made on copper sulfide crystals of compositions ranging from Cu1.8S to Cu2.0S and indium-doped Cu1.8S in the temperature region between 20°C and 220°C. Conductivity of Cu2-xS varied from 0.07 ohm-1cm-1 to 2400 ohm-1cm-1 as the deviation from stoichiometry increased from x=0 to x=0.2. It was found that Cu1.8S (digenite) and Cu1.96S (djurleite) undergo phase transitions at 90°C and at 93°C respectively. The transition temperature of Cu2S (chalcocite) increased from 98°C to 108°C as conductivity decreased from 52 ohm-1cm-1 to 0.07 ohm-1cm-1. An analysis of mixed conduction at β phase of low conductivity copper sulfide has shown that ionic conductivity is independent of the composition or the number of impurity cations in this material, and exhibits a temperature dependence with activation energy of 0.24 eV. Finally it is emphasized, after the discussion of the relation between electrical properties and crystal structure of copper sulfides, that the composition and crystalline phase are well characterized by the electrical conductivity in these materials.

The Electrical Conductivity of CaO ‐ Doped Nonstoichiometric Cerium Dioxide from 700° to 1500°C

Abstract: The electrical conductivity of sintered specimens of was measured over the temperature range 700°–1500°C and from 1 to 10−22 atm of oxygen. All specimens of exhibited mixed conduction. Two limiting case regions were observed. At low temperatures and high oxygen pressures, the conductivity is predominantly ionic. In this region the conductivity is independent of and between approximately 1 and 8 m/o is proportional to mole per cent . The following equation for ionic conductivity was obtained by fitting the conductivity data in this region to an expression derived on the basis of an oxygen vacancy model. An approximate expression for the diffusion coefficient for oxygen vacancies was calculated from the above expression and the Nernst‐Einstein relation. At high temperatures and low oxygen partial pressures and for lower contents the conductivity is predominantly electronic. In this region the magnitude and dependence of σ is similar to "pure" . A thermodynamic argument is also presented which favors oxygen vacancies as the nonstoichiometric defect in both pure and .

Electronic and Ionic Conduction in (AgxCu1-x)2Se

Abstract: The phase diagram is studied by X-ray and thermal analyses. The high temperature phase (α) is the solid solution of b.c.c. or f.c.c. in which Ag + , Cu + and electron are mobile. The galvanic cell Ag|AgI|specimen|Pt is available to controle the excess or deficit Ag density and to detect the electrochemical potential of Ag + , since the interdiffusion of Cu + into AgI is nearly forbidden except near Cu 2 Se. With the help of the cell and utilizing the weight-difference between Ag and Cu, the polarization and the interdiffusion are measured and interpreted with the diffusion theory. The electronic and ionic conductivities are measured with varying temperature and x . Further the various properties of α(Ag, Cu) 2 Se such as the conductivity, Hall coefficient, thermoelectric power, thermal conductivity etc. are measured and compared with the theory, indicating that the energy gap decreases with increasing x .

Hopping conductivity in highly anisotropic systems

Abstract: The temperature dependence of the phonon-activated d.c. conductivity is calculated for quasi one- and two-dimensional systems. For a one-dimensional system it is shown that the behaviour of σ(T) depends on the length of the chains and one obtains 1n σ = 1n σ0 − (T 0/T)I/n where n is 1 or 2, depending on temperature range and geometry. For low temperatures, purely one-dimensional hopping does not exist and an anisotropic two-dimensional model must be used.

Electrical Transport and Structural Properties of Bulk As-Te-I, As-Te-Ge, and As-Te Chalcogenide Glasses

Abstract: A variety of compositions of glass in the As-Te-I, As-Te-Ge, and As-Te chalcogenide series have been prepared and structurally analyzed The analytical techniques included x-ray powder diffraction, density determinations, and differential-scanning-calorimetry experiments The temperature dependence of the Hall mobility, Seebeck coefficient, and dc conductivity was determined for six representative alloy compositions The Hall mobility was found to be $n$-type, low, and activated with nearly equal activation energies in each case The conductivity mobility was deduced from the $p$-type Seebeck coefficients and the conductivity measurements to have an activated character with a characteristic energy of 019 \ifmmode\pm\else\textpm\fi{} 002 eV for all the measured compositions These results appear to be inconsistent with the familar Cohen-Fritzsche-Ovshinsky (CFO) picture for transport in amorphous semiconductors, and a new model for conduction in these glasses is proposed This model involves the hopping of holelike small polarons between sites associated with a common As-Te structural entity which is postulated to be present in all the alloys measured here The sign, magnitude, and temperature dependence of the dc conductivity, Seebeck coefficient, and Hall mobility are all consistent with this model

Note on the Anisotropy of the Conductivity in Thin Amorphous Films

Abstract: We present a new interpretation of the anisotropy of the conductivity in thin films of amorphous Ge and Si. The interpretation is based on a transition from percolation conduction to Miller and Abrahams's conduction at small film thickness. A simple theory, together with experimental data, is presented. The comparison between them is found to be good.

Solid silver ion conductors

Abstract: Materials exhibiting high ionic mobilities in the solid state at room temperature have mainly been found in the silver ion conductors which are based on silver iodide. Though silver iodide is a low conductivity solid at room temperature, it exhibits high ionic conductivity at relatively higher temperatures. In order to stabilize this high conductivity phase of silver iodide at room temperature, the introduction of foreign cations or anions into the lattice of silver iodide has been attempted. In this paper, the various silver ion high conductivity solids are reviewed, together with those showing both high ionic and electronic conductivity.

The Electrical Conductivity of Pyroxene

Abstract: The electrical conductivity of three natural orthopyroxene single crystals has been measured up to l,300°C and is shown to be dependent on oxygen fugacity. The presence of cleavage cracks and exsolution lamellae also has a large influence on the electrical conductivity. Temperatures calculated for the lunar interior from electrical conductivity data on pyroxenes under controlled oxygen fugacity are up to 700°C higher than previous calculations based on conductivity data for olivine.

Electrical Conductivity in Disordered Systems

Abstract: We investigate the temperature dependence of the hopping conductivity in a system in which hopping only takes place between nearest-neighbor centers. The system is simulated by a disordered classical-resistance network and analyzed in terms of percolation along critical paths and in terms of an effective-medium theory. The model is applied to the recent small-metal-particle experiments of Zeller.

Electrical conduction in hydrated collagen. I. Conductivity mechanisms.

Abstract: The electrical conductivity of bovine Achilles tendon with various amounts of adsorbed water was measuredas a function of temperature The conduction appeared to be fully determined by the water of hydration The current is probably primarily carried by protons at water contents up to 45% and by small ions at water contents beyond 65% In both ranges of water content, a linear relation between activation energy and water and content was found As to the lower range, this is explained by the action of Coulombic forces during the separation of proton–hydroxyl ion pairs In two regions of water content a linear relation between the logarithm of the pre-exponential factor and the activation energy was found There are, however, indications that at certain water contents the dissociation constant of the adsorbed water is several orders of magnitude higher than in liquid water

Conductivity of a system of metallic particles dispersed in an insulating medium

Abstract: The variation of the conductivity of metal‐particle—insulator systems with the volume percent of metal is explained in terms of an ``effective medium'' theory.

Studies of intermolecular interactions in planar metal complexes iii1 bis(ethylene-1,2-dithiolene) complexes of nickel, palladium, and platinum

Abstract: The synthesis and characterization of nineteen new bis-dithiolene metal complexes of the type A n +[MS4C4H4 n-], where A+ = various organic cations, M = Ni, Pd, Pt, and n = 0, 1, are described. The results of redox, infrared, electronic spectral, and NMR measurements on these complexes support a monomeric, planar structure for the complex units both in solution and, with the exception of the neutral MS4C4H4 (M = Pd, Pt) derivatives, in the solid state. However, evidence for intermolecular interactions in these solids has been found on the basis of four-probe conductivity measurements. The conductivities of these complexes range from less than 10−10 ohm−1 cm−1 to ∼ 10−5 ohm−1 cm−1 and depend markedly on the nature of A+, M and n. On the basis of these measurements, empirical generalizations relating conductivity and the structural parameters A+ and M are derived. In addition, information regarding the dependence of the conductivity on the spacial relationship of the complex units in the solid is o...

Temperature and volume dependence of the thermal conductivity of solid argon

Abstract: The temperature dependence of the isochoric thermal conductivity has been measured for five solid argon specimens with molar volumes between 22.14 ml and 24.06 ml. The results are in good agreement with the zero pressure data of previous workers provided that allowance is made for the thermal expansion of their specimens. Above 20 K the isochoric thermal conductivity was found to be inversely proportional to temperature as predicted by many theoretical models. The measured volume dependence of the conductivity can also be qualitatively understood in terms of these models.

Anionic Conductivity in Halogen‐Containing Lead Silicate Glasses

Abstract: The existence of anionic conductivity in halogen-containing lead silicate glasses was proved by Tubandt tests and electron microprobe examinations. Direct-current volume resistivities, loss tangents, and dielectric constants are reported for analogous glasses containing F−, Cl−, Br−, and I− and compared to those of the parent glass. The densities of the materials do not correlate with the dielectric-constant data.

Preparation and DC conductivity of an amorphous organic semiconducting system

Abstract: A series of semiconducting samples with noncrystalline structure was prepared by the thermal degradation of phenol formaldehyde resin at different heat treatment temperatures. DC measurements on these organic materials yield an interesting extension of the existing knowledge about the amorphous state. The most important result is the fact that pyrolyzed phenol formaldehyde resins show a temperature dependence on conductivity which is characteristic for the Mott hopping mechanism and identical with that of layers made by evaporating Ge, Si, GaAs or carbon. Hence it does not seem to be the chemical composition that is determining the mechanism of electrical conduction in amorphous solids but only the physical structure.

Electrical resistivity of RESn3 single crystals (RE = La, Ce, Pr, and Nd)

Abstract: The effects of 4f electrons on the electric properties of RESn/sub 3/ compounds were examined (RE denotes La, Ce, Pr, or Nd). Results of conductivity measurements performed on single crystals along the STA001! direction at 2 to 300 deg K by dc methods are prcsented graphically and analyzed. (JRD)

Fluctuation conductivity in the vicinity of the superconducting transition

Abstract: The conductivity of the metal in the vicinity of the superconductivity transition point has been obtained. The nonlinear fluctuation effects change the temperature dependence of the conductivity in a wide range of temperatures, in which fluctuation corrections to thermodynamic quantities are still small. At comparatively strong pair breaking these effects decrease the fluctuation correction, which may exceed the conductivity of normal metal far from the transition temperature.

The Dielectric Properties of Silicone Fluids

Abstract: The dielectric properties of polydimethylsiloxane fluids have been investigated under dc and ac fields as a function of field, frequency, temperature, and water content. The results of the ac studies have shown that the dielectric constant and dielectric loss of the fluid exhibit several transitions as a function of temperature at low temperatures. These transitions correlate reasonably well with structural changes in the fluid. The dielectric loss is also thermally activated and decreases rapidly with increasing frequency at ambient temperature. It is also weakly dependent on the applied field and the relative humidity. The dc properties exhibit a strong dependence of the conductivity on relative humidity. However, the dependence of the conductivity on the applied field is a complex one, and changes from an ohmic behavior at low fields, to a region of saturation at intermediate fields, and finally to an "ionization" region at high fields. The polydimethylsiloxane fluid also exhibits a reversal in the direction of the discharge current above a certain field, which is reminiscent of the electret effect observed in some polymeric solids. A tentative theoretical discussion of these properties is presented.

Carrier Generation Processes in Poly( N -Vinylcarbazole) Films

Abstract: Studies on the conductivity and photoconductivity of amorphous films of poly ($N$-vinylcarbazole) with Sn${\mathrm{O}}_{2}$ and metal electrodes show that the dark conductivity is dominated by the Richardson-Schottky field-assisted hole emission from positively biased metal electrodes, provided the metal work function is greater than 3.8 eV. When the metal electrode is negatively biased or with lower-work-function electrodes, the conductivity appears to be dominated by a bulk-polymer-film effect. The current-voltage characteristics of the latter effect do not support a Poole-Frenkel process. High-work-function metal electrodes in positive bias give rise to hole-photoemission tails in the photocurrent-action spectrum. A photocarrier generation process, which onsets at 1.8-1.9 eV and obscures hole photoemission from low-work-function metal electrodes, produces a linear dependence of photocurrent on light intensity and appears to be associated with electronic transitions in the polymer film.