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Coordination Numbers in Sm-Doped Ceria Using X-ray Absorption Spectroscopy
- Koettgen, Julius, Martin, Manfred
- Journal of physical chemistry 2019 v.123 no.11 pp. 6333-6339
- X-ray absorption spectroscopy, cations, ceric oxide, cerium, oxygen, physical chemistry
- Sm-doped ceria has one of the highest ionic conductivities reported for rare earth-doped cerium oxides. The high oxygen-ion conductivity can be attributed to the creation of oxygen vacancies by doping and weak defect interactions between oxygen vacancies and dopants. Especially, oxygen vacancies in the nearest neighborhood to dopants decrease the conductivity due to trapping and blocking. In this work, the local structure around the Ce cations is investigated using the extended X-ray absorption fine structure. The resulting coordination numbers of cerium coordinated by oxygen are only marginally larger than in a random oxygen vacancy distribution, explaining the large ionic conductivity.