Silver ion transport

About: Silver ion transport is a(n) research topic. Over the lifetime, 19 publication(s) have been published within this topic receiving 244 citation(s).

Oxidative dissolution of silver nanoparticles: A new theoretical approach

Abstract: A general model of an oxidative dissolution of silver particle suspensions was developed that rigorously considers the bulk and surface solute transport. A two-step surface reaction scheme was proposed that comprises the formation of the silver oxide phase by direct oxidation and the acidic dissolution of this phase leading to silver ion release. By considering this, a complete set of equations is formulated describing oxygen and silver ion transport to and from particles' surfaces. These equations are solved in some limiting cases of nanoparticle dissolution in dilute suspensions. The obtained kinetic equations were used for the interpretation of experimental data pertinent to the dissolution kinetics of citrate-stabilized silver nanoparticles. In these kinetic measurements the role of pH and bulk suspension concentration was quantitatively evaluated by using the atomic absorption spectrometry (AAS). It was shown that the theoretical model adequately reflects the main features of the experimental results, especially the significant increase in the dissolution rate for lower pH. Also the presence of two kinetic regimes was quantitatively explained in terms of the decrease in the coverage of the fast dissolving oxide layer. The overall silver dissolution rate constants characterizing these two regimes were determined.

Crystal Structure of the Solid Electrolyte(C5H5NH) Ag5I6 at -30°C

Abstract: The crystal structure of pyridinium hexaiodopentaargentate, (C5H5NH) Ag5l6, is unique among those of the halide and chalcogenide solid electrolytes in that face-sharing iodide octahedra as well as face-sharing tetrahedra and face-sharing between octahedra and tetrahedra provide the paths for silver ion transport. There are two formula units in a hexagonal cell, space group P6/mcc (D6h2). At -30°C, the lattice constants are a = 11.97 ± 0.02, c = 7.41 ± 0.01 A. The structure has three sets of sites for the silver ions. At -30°C two of these sets are apparently filled with the ten silver ions per unit cell, while the third set of tetrahedrally coordinated general positions is empty. Therefore, the conductivity at this temperature is limited by the thermal excitation of the silver ions into the empty tetrahedra.

The superionic Agl-Ag2O-V2O5 system: Electrical conductivity studies on glass and polycrystalline forms

Abstract: Superionic conducting glasses in the Agl-Ag2O-V2O5 system were prepared by heating the appropriate amounts of raw materials at 723 K and quenching in liquid nitrogen. The polycrystalline materials were prepared by slowly cooling the melt to room temperature. X-ray diffraction was used for material characterization. The electrical conductivity of the pulverized samples, pressed together with an electrode mixture of silver and electrolyte (1:2 by weight) under 5000 kg cm−2 pressure to form pellets 10 mm in diameter and 2 to 3 mm in thickness, was measured in the temperature range 300 to 365 K at 1 kHz. The ionic conductivities of the glasses were always higher than those of their polycrystalline counterparts, while their activation energies were also slightly higher. Conductivity measurements on annealed glassy samples indicated that the conductivity decreases with the time of annealing, and reaches a constant value which is nearly the same as that of the polycrystalline sample. Electronic conductivities of both types of sample were obtained by using Wagner's polarization cell technique, which showed that the electronic conductivity for both types was five orders of magnitude less than the total conductivity. Typical galvanic cells having the configuration Ag,electrolyte/electrolyte/C,electrolyte,I2 were constructed and the silver ion transport number was calculated by the e.m.f. method.

Highly Silver Ion-selective Transport Through Liquid Membranes Containing Cyclic and Acyclic Polythiamonoazaalkanes Bearing an Easily Ionizable Moiety

Abstract: Liquid membranes containing cyclic and acyclic tetrathiazaalkanes bearing a hydrazone moiety as a proton-dissociable group exhibited effective uphill silver ion transport behavior in the proton-driven cation transport. Excellent silver ion selectivities relative to other class ab and class b metal ions were observed for these membranes when citric acid was used for adjusting pH and for preventing hydrolysis of several metal ions in the source phase. Complete recovery of silver ion from a silver solder sample was selectively achieved using the liquid membrane containing acyclic tetrathiazaalkane hydrazone.

110Ag tracer diffusion study of percolation transition in Ag2S–As2S3 glasses

Abstract: Silver tracer diffusion study of homogeneous Ag 2 S-As 2 S 3 glasses has been realised over an extremely wide composition range covering nearly five orders of magnitude in the silver concentration from 4 × 10 4 % (4 ppm) to 33.3 at.% Ag. Three characteristic composition domains with drastically different ion transport properties have been found. (i) Below the percolation threshold at x c 3 × 10 -3 at.% Ag, the diffusion coefficients D Ag and activation energy E d do not depend on the silver content and similar to those in pure As 2 S 3 ; the silver ion transport number t Ag - is 0.10-0.14. (ii) In the critical region just above the percolation threshold (x=0.012-1.2 at.% Ag), the glasses are nearly pure Ag + ion conductors (t Ag >0.8), the ionic conductivity σ i (x) and diffusion coefficients D Ag (x) exhibit a power-law composition dependence: σ i αx 1 and D Ag X ' -1 with temperature-dependent power-law exponent t T 0 /T. (iii) At x> 15 at.% Ag, a well-known rather exponential increase of σ i (x) and D Ag (x) is observed with strongly correlated Ag + ion motion.