Julio C. Bazán

Conductivity in Na+- and Li+-montmorillonite as a function of equilibration humidity

Abstract A considerable influence of relative humidity on the conductivity of sodium and lithium-montmorillonite was found. At high humidity the conductivity values are similar for both type of samples and higher than those measured at low humidity, whereas the activation energies show the opposite relationship. In the low humidity zone the lithium-containing samples exhibit higher conductivity than that of the sodium ones. An explanation is given based on the different nature of the sorbed water and on the hydration power of the Li + and Na + ions.

On the kinetics of silver ion transfer at the solid—solid AgIAg interface

The transfer of silver ions from metallic silver to both alpha and beta silver iodide is studied by a dc transient technique. The results are interpreted in terms of a mechanism involving a charge transfer step followed by the silver ion incorporation into the solid electrolyte lattice. The relationship between the ecds obtained for both silver iodide forms is explained on the basis of the structural differences between both phases.

On the deviation from the theoretical behavior in applying Wagner's polarization method to the solid electrolyte cuprous iodide

Abstract An interpretation of the deviations from the theoretical behavior by the application of Wagners polarization method to CuI is presented. It is based on the effect of high polarization potentials on the defect concentration, which leads to a modification of the slope of the logarithm of the hole current versus applied potential curves.

Ion transport in hydrated sodium silicates (water glasses) of varying water content

Abstract Ionic conductivities in hydrated sodium silicate gels (water glasses) of SiO 2 /Na 2 O 3.41:1 mole ratio have been obtained by impedance spectroscopy at temperatures above and below the thermally determined glass transition temperature. Conductivities at T g are in the range 10 −6 to 10 −7 S cm −1 , which are similar to those found recently in several kinds of polymer electrolyte. It is suggested that the absence of a mixed alkali effect and a strong dependence on water imply that conductivities are largely protonic in nature and involve strong interactions between protons, water molecules and the silicate framework.

Influence of Cs+ ion on the co-ionic conductivity in the AgICuI solid system

Abstract The conductivity of AgI, CuI and AgCuI 2 with various amounts of CsI was studied. A decrease in the temperature range in which high conductivity appears was found for all cases, together with an increase in conductivity (except for AgI). Both types of change exhibit a linear relationship with the square root of added CsI.

Ionic conductivity in montmorillonite-doped silver iodide

Abstract The ionic conductivity of AgI–montmorillonite composites was studied at a temperature ranging from 35 to 520 °C. Composites with montmorillonite as small as 0.89 w/o exhibited a maximum of about eight times the conductivity of the pure β-AgI at low temperatures. These results, which can be ascribed to the large surface area of the clay, may be qualitatively explained on the basis of a stabilisation of the low-temperature, higher-conducting metastable γ-phase of AgI.

Conduction enhancement in solid silver bromide by heterogeneous doping with montmorillonite

The ionic conductivity of AgBr-montmorillonite composites from 0.9 to 30 volume percent in montmorillonite was studied in the range from 20 to 410°C. A remarkable increase in the conductivity at low temperatures is found. At 20°C a maximum value about 45 times higher than that of pure AgBr is reached at 2.6 v/o. A noticeable effect of humidity is also found. The results are qualitatively explained on the basis of the model proposed by Maier for heterogeneous doping of solid electrolytes.

On the behavior of the I-V characteristic curves on TeO2-V2O5-based glasses

Abstract This paper presents a direct experimental evidence supporting the electrothermal origin of a non-ohmic behavior on TeO2-V2O5-based glasses, with regard to a previously proposed model for the so-called ‘switching effect’. Results indicate that this deviation, enlarging with the pulse time length, may be explained by a Joule self-heating of the sample.

Thermodynamic data for solid AgI and its phase transitions from ENF measurements

Abstract From EMF measurements in the cell Ag(s)/AgI(s)/I2(g), graphite as a function of temperature, the enthalpy and entropy values for the formation of γ-, β- and α-AgI were obtained. From these data, the following thermodynamic quantities corresponding to the phase transitions were also calculated: ΔtHγ→β= -34.3 ±2 kJmol-1, ΔtSγ→β= -107 ± 4 Jmol-1K-1, ΔtHβ→α = 5.4 ± 2 kJmol-1, ΔtSβ→α = 23 ± 4 Jmol-1K-1.

On the influence of Cs(I)-doping on the electrical conductivity of cuprous bromide

A remarkable influence of Cs(I)-doping onto the conduction of the gamma-phase and on the gamma-beta transition in CuBr is found by means of DTA and conductivity measurements. The results are explained on the assumption of an increment of the defect concentration due to a lowering of its formation energy resulting from a lattice distortion in γ-CuBr.