Effect of microstructure and composition on ionic conductivity of rare-earth oxide-doped ceria
- Univ. of Utah, Salt Lake City, UT (United States). Dept. of Materials Science and Engineering
Polycrystalline ceria doped with several rare-earth oxides (Dy{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, Gd{sub 2}O{sub 3}, Ho{sub 2}O{sub 3}, La{sub 2}O{sub 3}, Nd{sub 2}O{sub 3}, Sm{sub w}O{sub 3}, and Yb{sub 2}O{sub 3}) at various concentrations were fabricated. Conductivity was measured by ac admittance and dc four-probe methods. The conductivity was separated into grain and grain boundary contributions using complex admittance technique as well as the grain size dependence of conductivity. The effect of dopant type and concentration on grain boundary conductivity was examined. Grain size dependence of polycrystalline conductivity, which can be adequately described by the so-called brick layer model, appears to give a more reliable measure of the grain conductivity compared to the complex admittance method. Polycrystalline resistivity (1/conductivity) increases linearly with the reciprocal of grain size. The intercept of resistivity vs. inverse grain size plot gives a measure of the grain resistivity, and the slope gives a measure of the grain boundary resistivity. Activation energies of polycrystalline conductivity, grain conductivity, and grain boundary conductivity were determined. A compositional analysis of fractured samples was carried out by Auger spectroscopy. The dopant concentration near grain boundaries was estimated to be lower than that in the bulk.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 599929
- Journal Information:
- Journal of the Electrochemical Society, Vol. 145, Issue 2; Other Information: PBD: Feb 1998
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
30 DIRECT ENERGY CONVERSION
CERIUM OXIDES
MICROSTRUCTURE
IONIC CONDUCTIVITY
SOLID ELECTROLYTE FUEL CELLS
DOPED MATERIALS
DYSPROSIUM OXIDES
ERBIUM OXIDES
GADOLINIUM OXIDES
HOLMIUM OXIDES
LANTHANUM OXIDES
NEODYMIUM OXIDES
SAMARIUM OXIDES
YTTERBIUM OXIDES
GRAIN SIZE
ACTIVATION ENERGY