Blocking grain boundaries in yttria-doped and undoped ceria ceramics of high purity
- Guo, X.
- Sigle, W.
- Maier, J.
DOIAbstract
CeO2 samples doped with 10, 1.0, and 0.1 mol% Y2O3 and undoped CeO2 samples of high purity were studied by impedance spectroscopy at temperatures <800degreesC and under various oxygen partial pressures. According to microstructural investigations by SEM and analytical STEM (equipped with EDXS), the grain boundaries were free of any second phase, providing direct grain-to-grain contacts. An amorphous siliceous phase was detected at only a few triple junctions, if at all; as a result, its contribution to the grain-boundary resistance was negligible. Nevertheless, the specific grain-boundary conductivities were still 2-7 orders of magnitude lower than the bulk conductivities, depending on dopant concentration, temperature, and oxyg...
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