Journal
ACTA MATERIALIA
Volume 57, Issue 12, Pages 3596-3605Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2009.04.017
Keywords
Ceria; Defect equilibria; Chemical expansion; Thermogravimetry; Surface chemistry
Funding
- US Department of Energy [DE-PS26-02NT41562, DE-AC05-76RL01830]
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Doped and undoped cerium(IV) oxides are ceramics commonly used as catalysts and as solid oxide fuel cell materials. In low oxygen partial pressure, ceria-based materials become non-stoichiometric and can form defect complexes that hinder ionic conductivity. In addition, oxygen non-stoichiometry induces strain (chemical expansion) that can result in stresses for composite or constrained applications. In this paper the non-stoichiometry and chemical expansion behavior has been measured in the temperature range 600-900 degrees C and in a wide oxygen partial pressure range. Surface oxygen non-stoichiometry has also been measured by comparing low surface area to high surface area samples. The bulk non-stoichiometry and chemical expansion behavior have been successfully modeled using a mass action formalism with defect complex formation to account for defect interactions. It has been found that surface defect concentration, previously ignored in the literature, can result in erroneous non-stoichiometry measurements. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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