期刊
SOLID STATE IONICS
卷 181, 期 33-34, 页码 1473-1477出版社
ELSEVIER
DOI: 10.1016/j.ssi.2010.09.001
关键词
Gadolinium-doped ceria; Chemical strain; Elasticity; Extended X-ray absorption fine structure spectroscopy (EXAFS); Thermal expansion
资金
- US-Israel Binational Science Foundation
- Israel Ministry of Science
- Israeli Science Foundation
- U.S. DOE [DE-FG02-03ER15476, DE-AC02-98CH10886, DE-FG02-05ER15688]
Self-supported films of CeO1.95 display time-scale dependent elastic moduli, a phenomenon which has been termed the chemical strain effect. In order to probe the possible structural origins of this behavior, extended X-ray absorption fine structure spectroscopy and X-ray diffraction were used. Evidence was found that, although this oxygen deficient ceria appears to maintain the fluorite structure on average, the mean Ce-O bond length is shorter than the mean Ce-oxygen vacancy distance. This finding is consistent with crystallographic data from more strongly reduced ceria in which the oxygen vacancies are ordered. By studying strain induced structural changes, we show that it is possible to relate this lattice distortion to the chemical strain effect. Similar conclusions were previously reached for films of Ce0.8Gd0.2O1.9. Since the ionic radii of both Gd3+ and Ce3+ are larger than that of Ce4+, we suggest that when cation dopants are larger than the host, ceria compounds containing a high concentration of oxygen vacancies may exhibit elastic anomalies. (C) 2010 Elsevier B.V. All rights reserved.
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