Preparation and sintering of Ce1-xGdxO2-x/2 nanopowders and their electrochemical and EPR characterization

Ce1-xGdxO(4-x)/2 (CGO; x=0.1; 0.2) nanopowders have been synthesised by various preparation procedures. The materials have been uniaxially pressed and sintered at 1450 degreesC to obtain high-density ceramic pellets (rho(rel)greater than or equal to96%). The microstructural properties were investigated by electron microscopy and X-ray diffraction. It has been observed that these properties influence bulk resistance, which represents a significant contribution to the overall device resistance in intermediate-temperature electrochemical devices. The degree of electronic conductivity in the materials is associated with the occurrence of Ce3+ ions generally caused by the exposure to very low oxygen partial pressures or reduced conditions. It has been found by electron paramagnetic resonance (EPR) analysis that electron conductivity occurs on the 10% doped CGO powder even under air exposure, whereas it does not vary with the preparation procedure. (C) 2004 Elsevier B.V. All rights reserved.