Surface diffusion, migration, and conjugated processes at heterophase interfaces between WO3 and MeWO4 (Me = Ca, Sr, Ba) / Neiman A. Ya.,Pestereva N. N.,Tsipis E. V. // RUSSIAN JOURNAL OF ELECTROCHEMISTRY. - 2007. - V. 43, l. 6. - P. 672-681.

ISSN/EISSN:

1023-1935 / нет данных

Type:

Article

Abstract:

With the aid of a complex of methods it is demonstrated that at heterophase interfaces between WO3 and MeWO4 (Me = Ca, Sr, Ba) there occurs penetration of components WO3 and MeWO4 into one another under spontaneous conditions and after the imposition of an electric field. Experimental data concerning the electrosurface migration in potentiostatic and galvanostatic regimes are compared. It is demonstrated that the amount of WO3 transported onto inner surface of MeWO4 is defined by the magnitude of the electric charges passed through the system but does not depend on the I-U parameters of experiment. It is established that the magnitude of the faradaic efficiency of the WO3 transport in an electric field at 900 degrees C is close for all compounds of the type MeWO4 (Me = Ca, Sr, Ba) and amounts to 0.42 +/- 0.02 for a galvanostatic regime of the process. Methods of x-ray diffraction analysis, x-ray-fluorescence analysis, XPS, and electron microscopy are employed to explore the properties and compositions of regions adjacent to the WO3 vertical bar MeWO4 interface after experiments in spontaneous and field-induced regimes. Data are obtained that confirm the reality of formation of nonautonomous phase MeW-s and its crucial role in the origin and mechanism of processes that occur at the heterophase interface WO3 vertical bar MeWO4. The real architecture of the interface may be portrayed by the scheme WO3 : MeW-s vertical bar MeW-s: MeWO4, which reflects penetration of MeW-s into both initial briquettes. The reasons for the loss of weight of briquettes of MeWO4 when annealed in contact with WO3 under spontaneous conditions are analyzed. It is shown that the weight loss may be caused by congruent sublimation of the MeW-s phase, which is directly connected with its low surface energy and relatively low sublimation energy.

Author keywords:

electrosurface migration of oxides; heterophase interface; nonautonomous phase; faradaic efficiency

DOI:

10.1134/S1023193507060109

Web of Science ID:

ISI:000247977600010

Соавторы в МНС:

Другие поля

Поле	Значение
Month	JUN
Publisher	MAIK NAUKA/INTERPERIODICA/SPRINGER
Address	233 SPRING ST, NEW YORK, NY 10013-1578 USA
Language	English
Research-Areas	Electrochemistry
Web-of-Science-Categories	Electrochemistry
ResearcherID-Numbers	Grupo, AE/B-3302-2014 Tsipis, Ekaterina/A-3590-2015
ORCID-Numbers	Grupo, AE/0000-0002-0913-4772 Tsipis, Ekaterina/0000-0002-1458-484X
Number-of-Cited-References	11
Usage-Count-Last-180-days	3
Usage-Count-Since-2013	9
Journal-ISO	Russ. J. Electrochem.
Doc-Delivery-Number	189GO