Showing papers on "Ionic conductivity published in 1972"

High oxide ion conduction in sintered Bi2O3 containing SrO, CaO or La2O3

Abstract: Ionic conduction in sintered oxides of the system Bi2O3-SrO was investigated by measuring the conductivity and ion transference number under various conditions. The ion transference numbers were measured by an oxygen concentration cell employing the specimen as the electrolyte.

Thermally fixed holograms in linbo3

Abstract: Normally recorded phase holograms in undoped LiNbO3 can be made optically stable, i.e. fixed, by heating the crystal to roughly 100°C. A detailed study of the temperature dependence of this process, coupled with conductivity measurements, suggests a model in which the fixed holograms are associated with ionic charge patterns formed by drift of thermally activated ions in the electric field pattern of the original hologram. These ions would have an activation energy of ∼ 1.1 eV and a concentration in excess of 2 × 1013 cm-3 in fair agreement with previous measurements of ionic conductivity. The room temperature conductivity of the LiNbO3 used in our experiments is concluded to be less than 10-17 Ω cm)-1.

Ionic Conduction of Impurity-Doped β-Alumina Ceramics

Abstract: Beta alumina (Na2O11 Al2O3) with addition of MgO, NiO, ZnO, CuO and CaO, respectively, together with Na2O are sintered. Ionic conduction of Na+ and X-ray diffraction of these samples are investigated. Additions of above divalent ions, except for Ca2+, increase the amount of Na+ in β-alumina, leading to an increase in the ionic conduction of Na+ in β-alumina. All divalent ions effective to increase the ionic conduction are components of aluminum spinel. The limiting process of the D.C. ionic conduction of these sintered samples may be the grain-boundary conduction.

An investigation of the thermal defect order, defect mobility, and defect complex formation in cadmium fluoride. (Ionic conduction)

Abstract: The dependence of the resistance and ionic thermal currents (ITC) and CdF2 crystals on the NaF and YF3 content, temperature, applied voltage and other factors has been investigated. It is shown that the current passing through the crystals is due to the transport of anion vacancies and fluorine interstitials, which under favourable conditions associate with the monovalent sodium and the trivalent yttrium impurity respectively. It is further shown that the observed ITC signals are due to the accumulation of charge carriers (space charge) and defect-impurity complexes at the electrodes. The energies of formation of the defect-impurity complexes and the activation energy of motion of the defects are obtained from both kinds of measurements independently and good agreement is found between the respective values. The energies of formation of the intrinsic defect pairs are also obtained from the conductivity measurements.

Solid state ionics. High ionic conductivity solid in silver halide-silver sulphate system

Abstract: The ionic conductivities and phase diagrams of AgI-Ag2SO4, AgCl-Ag2SO4 and AgBr-Ag2SO4 systems have been studied with the help of electrical conductivity, transport number, DTA and X-ray studies. In the AgI-Ag2SO4 system, the solid solution of α-AgI with Ag2SO4 was quenched to room temperature to have high ionic conductivity of 5·0×10−2 (ohm. cm)−1 at room temperature and 1·3×10−3 (ohm. cm)−1 at −78°C. The quenched solid solution was stable at −20°C, but gradually decomposed toβ-AgI andβ-Ag2SO4 at room temperature. The transport number of silver ion in this solid solution was about 1·0. In the AgCl-Ag2SO4 and AgBr-Ag2SO4 systems, the electrical conductivity was of the order of 10−4 to 10−6 (ohm. cm)−1 at room temperature.

Beta alumina production

Abstract: WHEN A MIXTURE OF POWDERS OF AN OXIDIC ALUMINUM COMPOUND, AN OXIDIC SODIUM COMPOUND AND OPTIONALLY ADDITIVES, IS HOT-PRESSED INTO A SOLID BODY AT A TEMPERATURE OF FROM ABOUT 100*C. TO ABOUT 1800*C. AND A PRESSURE OF GREATER THAN ABOUT 100 P.S.I. AND THE BODY IS THEN HOT-FORGED AT SIMILAR CONDITIONS A SODIUM BETA ALUMINA HAVING AN ORIENTED CRYSTAL STRUCTURE AND THUS A HIGH IONIC CONDUCTIVITY RESULTS.

Ionic Conductivity (Including Self-Diffusion)

Abstract: Ionic conductivity has become relevant. The recent revival of interest in electric automobiles and solid-state batteries has led to production of high-conductivity solid electrolytes. These new high-conductivity materials, such as RbAg4I5,1,2 have greatly expanded the range over which ionic transport phenomena in solids have been observed. In Fig. 1, we show the conductivity of RbAg4I5 in comparison with the conductivity of the more common alkali and silver halides. We find grouped together on the left-hand, or high-temperature, side of the figure the alkali halide crystals. These materials have been extensively studied.* They are excellent insulators at room temperature and only have significant electrical conductivity within a few hundred degrees of their melting temperatures. Furthermore, in this high-temperature region, the conductivity of the alkali halides is strongly temperature-dependent, the conductivity changes by about 3% per degree Celsius, and the activation energy for conduction is about 2 eV. To the right in Fig. 1, we move to lower temperatures and to materials less well characterized than the alkali halides. The cesium and ammonium halides have ionic conductivities that are about equal in magnitude to the alkali halides but are less strongly temperature-dependent, with activation energies of 1.2 eV. With a conductivity higher by three orders of magnitude, we find silver chloride, with an activation energy for conduction of less than 1 eV.

Thermally Fixed Holograms in LiNbO 3

Abstract: Normally recorded phase holograms in undoped LiNbO, can be made optically stable. i.e. fixed. by heating the crystal to roughly 100°C. A detailed study of the temperature dependence of this process. coupled with conductivity measurements, suggests a model in which the fixed holograms are associated with ionic charge patterns formed by drift of thermally acti\ated ions in the electric field pattern of the original hologram. These ions would have an activation energy of - 1.1 e\’ and a concentratlon in excess of ‘7 x 10” cm-J in fair agreement with previous measurements of ionic conductivity. The room temperature conductivity of the LiNbO, used in our experiments is concluded to he less than lo-’’ (a cm)- ’.

Electrical and Structural Properties of Metal Sulfides in Chloride Melts The Systems and

Abstract: The phase diagrams of the systems and and the densities of the liquid solutions have been measured over the permissible concentration and temperature ranges. Specific conductivities of the liquid mixtures have also been determined. The results indicate that the solutions, for concentrations up to about 30 m/o (mole per cent) and temperatures below 1000 °C, are essentially ionic conductors. Electronic conductance becomes evident for the more concentrated solutions. In the solutions, ionic conductivity appears to be restricted to concentrations below .The thermodynamic calculations from the phase diagram and the structural interpretation of the density measurements indicate that dimers are present in dilute solutions. Further association occurs at higher concentrations and the formation of a continuous sulfide network appears to be related to the onset of electronic conduction. The solubility of copper metal in cuprous chloride is very low, and the conductivity of cuprous chloride, and of cuprous chloride‐rich melts with cuprous sulfide, appears unaffected by the presence of copper metal. The addition of excess copper metal to molten cuprous sulfide, however, greatly increases its electrical conductivity.Because the electrical conductivities of cuprous and ferrous sulfides are predominantly electronic in nature electrodeposition from the molten sulfides is not feasible. Electrolysis of solutions of in in the composition and temperature ranges of ionic behavior yielded copper metal at the cathode with high current efficiencies. Copper metal was also recovered selectively from solutions of a synthetic matte dissolved in molten . It is also shown that may be extracted from a synthetic matte by solvent extraction using molten at the appropriate temperatures. The extraction is attributed to an exchange reaction which converts the component into the soluble ionic form of .

Solid electrolyte compact for probe used in quantitative determination of gas dissolved in molten metal

Abstract: SOLID ELECTROLYTE COMPACTS ARE PROVIDED FOR USE IN A PROBE TIP FOR THE QUANTITATIVE DETERMINATION OF GAS DISSOLVED IN MOLTEN METAL, THE ELECTROLYTE BEING AN ELONGATED COMPACT FORMED OF SOLID OXIDE ELECTROLYTE BEING AN ELONGATED TAINS ITS IONIC CONDUCTION PROPERTIES AND WHICH DOES NOT EXHIBIT SUBSTANTIAL ELECTRONIC CONDUCTION PROPERTIES AT HE TEMPERATURE OF THE MOLTEN METAL, SAID SOLID ELECTROLYTE BEING, FOR EXAMPLE, LIME-STABILIZED ZIRCONIA. THE COMPACT ALSO INCLUDES A FUGITIVE BINDER, E.G., POLYVINYL ALCOHOL, AND OPTIONALLY CONTAINS A SMALL AMOUNT OF A SUITABLE HIGH TEMPERATURE BINDER. THE COMPACT IS PROVIDED WITH A BEADED WIRE-ACCEPTING DEPRESSION AXIALLY THEREIN.

Theory of Ionic Conduction in Solids

Abstract: When a constant field in the 10 V cm−1 range is applied to annealed anodic oxide films the ion current builds up in accelerating fashion. It is shown that a model in which the ions move through channels in the oxide and in which the moving ions clear the initially blocked channels reproduces the general form of the ion current vs. time behavior. Dignam's theory of this process is discussed. A recent claim that considerations of mean free path render inapplicable to these films models in which the concentration of ions changes with field due to homogeneous generation of Frenkel defects is shown to be unjustified.A further observed phenomenon in which the latent ionic conductivity of the films decays at zero field is also discussed in terms of the competing models.

Transport Properties of Thoria and Thoria-based Solid Solutions

Abstract: Abstract The methods for obtaining transport numbers in oxides are described and associated experimental difficulties are discussed. Their reliability is assessed and used in conjunction with related data to offer a consistent picture for thoria and thoria-based solutions between 500° and 1600 °C. Both are ionic conductors within certain ranges of oxygen pressure. It is concluded that, for ThO2, and, for ThO2 -Y2O3 solutions (10-20 mole % YO1.5), where P⊕ P⊖ , respectively, are the oxygen pressures (atm) where the ionic and p-type and the ionic and n-type conductivities are equal. Ionic conductivity and charge carrier mobilities in thoria are briefly considered

Electrical conduction in ammonium perchlorate

Abstract: D.c. along with a few a.c. electrical measurements are reported for ammonium perchlorate (AP) in compressed disc and single crystal form. The near-identity of the electrical conductivity of AP to that of certain other alkali perchlorates (also measured) makes conduction by protons according to schemes previously suggested unlikely though not impossible. The non-ohmic behaviour of ammonium perchlorate single crystals shows that the “classical” theory of ionic conduction based on the migration and creation of point defects is not adequate to describe fully the conduction process. The possibility of various electronic mechanisms, including Schottky emission of electrons from the metallic electrodes with associated carrier injection into the crystal is discussed. As none of these mechanisms is entirely satisfactory, the electrical conductivity of AP is thus considered to be complex and, in particular, to be controlled by a number of processes operative under different conditions of temperature, applied field and gas pressure.

Ionic Conduction in Polymers

Abstract: The mechanism of ionic current flow through three polymer films immersed in electrolyte was investigated using current-voltage measurements Results suggest that conductivity changes result from changes in the dissociation energy of ionogenic groups on ingress of water

An Experiment in Solid State Chemistry: Conduction in Silver Iodide.

Abstract: Investigating the ionic conduction in silver iodide is a mechanically simple experiment designed to illustrate several important ideas relevant to the study of defects in solids.