Re-examination of bulk and grain boundary conductivities of Ce(1-x)Gd(x)O(2-delta) ceramics
authors Perez-Coll, D; Nunez, P; Ruiz-Morales, JC; Pena-Martinez, J; Frade, JR
nationality International
journal ELECTROCHIMICA ACTA
author keywords gadolinium-doped ceria; impedance spectra; cobalt additive; sinterization; ionic conductivity
keywords DOPED CERIA ELECTROLYTES; IONIC-CONDUCTIVITY; ELECTRICAL-PROPERTIES; SOLID-SOLUTIONS; HIGH-PURITY; OXALATE COPRECIPITATION; ELECTRONIC TRANSPORT; STABILIZED ZIRCONIA; REDUCING CONDITIONS; LATTICE-PARAMETERS
abstract Powders of gadolinium-doped ceria solid solutions, Ce(1-x)Gd(x)O(2-delta) (x = 0.05, 0.1, 0.2, 0.3 and 0.4), were prepared by a freeze-drying precursor route. Dense ceramic pellets with average grain sizes in the range of several microns were obtained after sintering at 1600 degrees C. Cobalt nitrate was added to the powders to obtain dense ceramic samples with grain sizes in the submicrometer range at 1150 degrees C. The ionic conduction was analysed by impedance spectroscopy in air, to de-convolute the bulk and grain boundary contributions. The bulk conductivity at low temperature clearly decreases with increasing content of Gd whereas the activation energy increases. An alternative method is proposed to analyse the extent of defect interactions on conduction. For samples without addition of Co, the specific grain boundary conductivity increases with increasing Gd content. Addition of cobalt does not alter the bulk properties but produces an important increase in the specific grain boundary conductivity, mainly in samples with lower Gd-concentration (x = 0.05 and 0.1). Segregation of Gd and its strong interaction with charge carriers may explain the blocking effects of grain boundaries. (c) 2006 Elsevier Ltd. All rights reserved.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 0013-4686
year published 2007
volume 52
issue 5
beginning page 2001
ending page 2008
digital object identifier (doi) 10.1016/j.electacta.2006.08.009
web of science category Electrochemistry
subject category Electrochemistry
unique article identifier WOS:000243647700022
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