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Dopant site selectivity in BaCe0.85M0.15O3-δ by extended x-ray absorption fine structure

Wu, J. and Webb, S. M. and Brennan, S. and Haile, S. M. (2005) Dopant site selectivity in BaCe0.85M0.15O3-δ by extended x-ray absorption fine structure. Journal of Applied Physics, 97 (5). Art. No. 054101. ISSN 0021-8979. http://resolver.caltech.edu/CaltechAUTHORS:WUJjap05

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Abstract

Rare earth doped BaCeO3 has been widely investigated as a proton conducting material. Trivalent dopants are generally assumed to fully occupy the Ce4+-site, and thereby introduce oxygen vacancies into the perovskite structure. Recent studies indicate the possibility of partial dopant incorporation onto the Ba2+-site concomitant with BaO evaporation, reducing the oxygen vacancy content. Because proton incorporation requires, as a first step, the generation of oxygen vacancies such dopant partitioning is detrimental to protonic conductivity. A quantitative Extended X-ray Absorption Fine Structure (EXAFS) study of BaCe0.85M0.15O3-δ (M=Yb,Gd) is presented here along with complementary x-ray powder diffraction and electron probe chemical analyses. The EXAFS results demonstrate that as much as 4.6% of the ytterbium and 7.2% of the gadolinium intended for incorporation onto the Ce site, in fact, resides on the Ba site. The results are in qualitative agreement with the diffraction and chemical analyses, which additionally show an even greater extent of Nd incorporation on the Ba site.


Item Type:Article
Additional Information:© 2005 American Institute of Physics. Received: 17 February 2004; accepted: 12 November 2004; published online: 10 February 2005. The authors thank Wilhelmia (Lala) Espinosa for help preparing samples, Dr. Chi Ma for assistance with the microprobe chemical analysis and Dr. John Bargar for advice on EXAFS analysis. This work is funded by the Department of Energy, Office of Energy Efficiency and Renewable Energy. Additional support is provided by the National Science Foundation through its support of the Caltech Center for the Science and Engineering of Materials. Portions of this research were carried out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. The SSRL Structural Molecular Biology Program is supported by the Department of Energy, Office of Biological and Environmental Research, and by the National Institutes of Health, National Center for Research Resources, Biomedical Technology Program.
Subject Keywords:BARIUM CERATE; BACEO3; NONSTOICHIOMETRY; CONDUCTION; TRANSPORT
Record Number:CaltechAUTHORS:WUJjap05
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:WUJjap05
Alternative URL:http://dx.doi.org/10.1063/1.1846946
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3561
Collection:CaltechAUTHORS
Deposited By: Lindsay Cleary
Deposited On:15 Jun 2006
Last Modified:26 Dec 2012 08:55

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