Electrochemical permeability of La0.9Sr0.1Ga1-xFexO3-delta

The present work reports estimates for the hole conductivity of lanthanum g allate-based samples (La0.9Sr0.1Ga1-x FexO3-sigma, with x = 0 and x = 0.2), in the range 700-1000 degrees C. These estimates were based on electrochem ical permeability measurements, and were compared to previous estimates obt ained from ion-blocking measurements. The p-type conductivity of these mate rials was confirmed to be strongly influenced by the content of Fe. The act ivation energy for p-type conductivity was found to be in the range 0.9-1 e V, lower than usually observed for alternative electrolytes based in zircon ia or ceria. The increase in p-type conductivity with Fe content can be exp lained by a relatively easy formation of Fe4+ ions under oxidizing conditio ns, a basic requirement for the establishment of a small polaron-type condu ction mechanism. (C) 2000 Elsevier Science Ltd. All rights reserved.