Defect thermodynamic and transport properties of nanocrystalline Gd-doped ceria |
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Authors: | S Surble G Baldinozzi M Dollé D Gosset C Petot G Petot-Ervas |
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Institution: | (1) Research Group CNRS/SPMS- Ecole Centrale Paris, 92295 Chatenay Malabry/SRMA-CEA Saclay, 91191 Gif sur Yvette, France |
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Abstract: | Nanocrystalline CeO2-doped (5, 7.5, 10, and 15 mol%) Gd2O3 powders, with a particle size of about 17 nm, were synthesized through the combustion of glycine/nitrate gels. Dense nanocrystalline
materials were obtained by hot uniaxial sintering. Optical microscopy, scanning electron microscopy and transmission electron
microscopy examinations, as well as X-ray diffraction analyses, have allowed us to characterize these polycrystals. The grain
sizes, included between ∼10 and 80 nm, depend on both the sintering temperature and the amount of dopant. A comparison of
the transport properties of these nanocrystalline samples to the values obtained with coarsened grained materials of same
composition shows that the ionic conductivity passes through a maximum for mean grain sizes included between 300 and 500 nm.
Furthermore, an enhancement of the ionic conductivity is observed when the amount of dopant increases. This was attributed
to a grain-size-dependent gadolinium segregation at the periphery of the grains confirmed by X-ray photoelectron spectroscopy
characterizations.
Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, France, 9–15 Sept. 2007. |
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Keywords: | Yttria-doped Ceria Nanocrystalline materials Segregation Ionic conductivity SOFC |
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