Transport numbers and ionic conduction of eutectic methacomposites \{(1-x)MeWO4 center dot xWO(3)\} (Me = Sr, Ba; x=0-0.55) / Pestereva N. N.,Zhukova A. Yu.,Neiman A. Ya. // RUSSIAN JOURNAL OF ELECTROCHEMISTRY. - 2007. - V. 43, l. 11. - P. 1305-1313.

ISSN/EISSN:

1023-1935 / нет данных

Type:

Article

Abstract:

Transport numbers of oxygen ions, t(O2-) in methacomposites (1 - x) MeWO4 center dot xWO(3), where Me = Sr and Ba and x = 0 - 0.55, are determined in the temperature interval 600 to 900 C by a method of the emf of an oxygen - air galvanic cell. It is demonstrated that the region of small contents of the additive (x <= 0.2) is predominantly characterized by oxygen- ion conduction (t(O2-) = 1), which gives way to electronic conduction ( t e = 1) at x > 0.35. It is confirmed once again that subeutectic compositions (1 - x) MeWO4 center dot xWO(3) where Me = Sr and Ba and x = 0 - 0.2 belong in the class of ion-conducting methacomposites. The threshold of percolation of electronic conduction (t(e) >= 0.5, t(O2-) < 0.5) occurs at x(t) = 0.3. Dependences of the transport numbers of the oxygen ions on the volume ratio between components in both composites resemble one another; specifically, the threshold composition contains nearly 20 vol \% of WO3. The dramatic amplification (by 1 - 1.5 orders of magnitude) of the ionic conductivity in the methacomposites occurs at small contents of tungstic oxide (x <= 0.01). A chemical transport removal of excess tungstic oxide, which is segregated in the form of the surface compound MeW-s, from the surface of the MeWO4 grains destroys MeW-s, leading to a 10 - 15- fold drop of the ionic conductance. At x >= 0.05, the oxygen-ion conductance in the methacomposites is practically independent of their composition. A model for the formation and architecture of the methacomposites is qualitatively modified. The modified model takes into account doubled surface activity and mobility of the MeW-s phase with respect to MeWO4 and WO3.

Author keywords:

composites; methacomposite effect; transport numbers of charge carriers; emf method; ionic conduction; methacomposite formation model; non-autonomous phase PHASE

DOI:

10.1134/S1023193507110158

Web of Science ID:

ISI:000251190800015

Соавторы в МНС:

Другие поля

Поле	Значение
Month	NOV
Publisher	MAIK NAUKA/INTERPERIODICA/SPRINGER
Address	233 SPRING ST, NEW YORK, NY 10013-1578 USA
Language	English
Keywords-Plus	PHASE
Research-Areas	Electrochemistry
Web-of-Science-Categories	Electrochemistry
Author-Email	arkady.neiman@usu.ru
Number-of-Cited-References	19
Usage-Count-Since-2013	7
Journal-ISO	Russ. J. Electrochem.
Doc-Delivery-Number	234UZ