Anomalous Diffusion Coefficients for W(IV) Ion Diffusion in NaCl-KCl Melt at 700-750°C

2010 ◽  
Vol 297-301 ◽  
pp. 1481-1486 ◽  
Author(s):  
Alex Lugovskoy ◽  
Z. Unger ◽  
Michael Zinigrad ◽  
D. Aurbach
Keyword(s):  
Cyclic Voltammetry ◽  
Anomalous Diffusion ◽  
Diffusion Coefficients ◽  
Ion Diffusion ◽  
Tungsten Electrodes ◽  
And Tungsten

The electrodepostion of bi-valent iron, zinc and tungsten (IV) on tungsten electrodes in equimolar NaCl-KCl melt at 700-750oC was studied by Cyclic Voltammetry and Chronoamperometry. While iron (II) and zinc (II) ions demonstrate regular values of diffusion coefficients, which are all in the range of 10-6-10-5 cm2/sec, tungsten (IV) ions diffuse considerably slower. Plausible process mechanisms were proposed, according to which the tungsten (IV) ions form polynuclear ions and these massive species diffuse at considerably more moderate rates.

Hydrophobic Ferrocene Derivatives as Potential Standards in Electrochemistry

1997 ◽  
Vol 62 (2) ◽  
pp. 185-198 ◽  
Author(s):  
Jaroslav Podlaha ◽  
Petr Štěpnička ◽  
Róbert Gyepes ◽  
Vladimír Mareček ◽  
Alexander Lhotský ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cyclic Voltammetry ◽  
Redox Potential ◽  
Diffusion Coefficients ◽  
Carbon Electrodes ◽  
X Ray Diffraction ◽  
Ferrocene Derivatives ◽  
X Ray ◽  
Special Cases ◽  
As Solubility

Ferrocene (FcH) derivatives monosubstituted by palmitoyl (1), hexadecyl (2), 1-adamantoyl (3) or 1-adamantylmethyl (4) groups were sythesized and characterized by NMR, mass and 57Fe Mossbauer spectroscopy. The structure of 1-adamantoylferrocene was determined by single-crystal X-ray diffraction. Cyclic voltammetry on gold and glass-like carbon electrodes demonstrated that the compounds can serve as electrochemical standards for special cases since their ferrocene/ferricinium redox potential remains stable and reversible, while the properties such as solubility, diffusion coefficients and surface tension are strongly solvent-dependent.

The precision measurement of single ion diffusion coefficients

1958 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
R Mills ◽  
EW Godbole
Keyword(s):  
Precision Measurement ◽  
Diffusion Coefficients ◽  
Electrolyte Solutions ◽  
Radioactive Material ◽  
Ion Diffusion ◽  
Capillary Method ◽  
Dilute Electrolyte Solutions

The precision measurement of single ion diffusion coefficients in dilute electrolyte solutions would be of considerable value. A method is described which is capable of giving the required precision. It involves a modification of the open-ended capillary method by enclosure of the capillary of diffusing radioactive material in a scintillator so that its contents can be continually monitored during the course of diffusion.

Werkstoffaufbau und diffusiver Stofftransport aufgezeigt an ausgewählten Beispielen / Material structure and diffusive mass transport as pointed out by means of selected examples

2000 ◽  
Vol 6 (4) ◽  
pp. 429-450
Author(s):  
R. Kriegel ◽  
A. Buchwald ◽  
Ch. Kaps
Keyword(s):  
Mass Transport ◽  
Diffusion Coefficients ◽  
Transport Mechanism ◽  
Diffusion Models ◽  
Second Law ◽  
Material Structure ◽  
Ion Diffusion ◽  
Oxygen Ion ◽  
Oxygen Ion Diffusion

Abstract The diffusive mass transport in materials is above all determined by the material structure. The experimental determination of diffusion coefficients is based on diffusion models, which results from special mathematical solutions of Fick's second law and its corresponding boundary conditions. The general usefulness of these diffusion models will be described using some examples, e. g. the diffusion of deteriorating salts in masonry materials, the oxygen ion diffusion in mixed conducting ceramics and the cation exchange in single crystals. The measurement of the diffusion coefficients results in a better comprehension of the transport mechanism as well as of the "morphology" of the transport medium, which allows to optimize the conditions of the mass transport and the material structure and composition, respectively.

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