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Effects of Fe-additions on sintering and transport properties of Yb2Ti2 − yFeyO7 − δ

✍ Scribed by A.L. Horovistiz; D.P. Fagg; J.C.C. Abrantes; J.R. Frade


Publisher
Elsevier Science
Year
2007
Tongue
English
Weight
318 KB
Volume
27
Category
Article
ISSN
0955-2219

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✦ Synopsis


Partial substitution of Fe for Ti in Yb 2 Ti 2 -y Fe y O 7 -δ has been used to improve the sinterability of these ion conducting pyrochlore-type materials, and to adjust their transport properties. Fe additions displace the maximum shrinkage rate to lower temperatures and allow the preparation of dense materials at lower firing temperatures. Impedance spectroscopy was used to de-convolute the effects of Fe additions on the bulk and grain boundary conductivities. The bulk conductivity was enhanced for relatively low Fe additions (<5%) and its activation energy was lowered. The grain boundary conductivity was also enhanced. The dependence of total conductivity on oxygen partial pressure shows that this enhancement corresponds to ionic conductivity. The onset of n-type conductivity is displaced to more reducing conditions with Fe addition.


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