Structural and electrical properties of BaCe(0.9)Ee(0.1)O(2.95) electrolyte for IT-SOFCs

Abstract

BaCe(0.9)Ee(0.1)O(2.95) (BCE) nanopowder was synthesized by citric-nitric autocombustion method. Rietveld refinement analysis showed that unit cell volume was slightly larger compared with the most known BaCe0.9Y0.1O2.95, which might contribute to higher proton mobility. Sinterability of BaCeO3 is also enhanced by doping with Eu, since dense single-phased BCE electrolyte microstructure comprising of 1-2mm grains was obtained after sintering at 1450 degrees C for 5 h. The electrochemical impedance spectroscopy (EIS) analysis revealed separate bulk and grain boundary contributions to the total electrolyte conductivity below 200 degrees C. The grain boundary conductivity was one to two orders of magnitude lower than the bulk conductivity, indicating blocking effect of the grain boundaries to the mobility of charge carriers. This effect diminished completely above 500 degrees C and only total conductivities were determined between 500 and 700 degrees C. Conductivity of BCE in a wet hydrogen atmosphere at 600 degrees C reached 1.2 x 10(-2) S/cm, which can be considered as one of the highest conductivities among BaCeO3 based proton conductors. (C) 2015 Elsevier Ltd. All rights reserved.