Chemical expansion of nonstoichiometric Pr0.1Ce0.9O2−δ: Correlation with defect equilibrium model

Undoped and acceptor doped cerium dioxide is known to exhibit non-stoichiometry induced chemical expansion at elevated temperatures and reducing environments with impact on the mechanical integrity of solid oxide fuel cells and permeation membranes. In this paper, the chemical expansion of Pr0.1Ce0.9O2−δ is measured and analyzed with respect to its defect equilibria and the chemical coefficient of expansion, analogous to thermal coefficient of expansion, is extracted. The addition of Pr to CeO2 leads to major deviations from stoichiometry, and correspondingly to large chemical expansions, under readily accessible experimental conditions (e.g. in air at elevated temperatures). Pr0.1Ce0.9O2−δ, therefore, serves as a model system for studying chemical expansion in ceria-based solid solutions in order to predict the conditions in which they exhibit suppressed chemical expansion.