Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10629532 | Journal of the European Ceramic Society | 2014 | 13 Pages |
Abstract
The thermal and chemical expansion of Ba0.5Sr0.5Co0.8Fe0.2O3âδ (BSCF) and SrCo0.8Fe0.2O3âδ (SCF) mixed ionic-electronic conductors were studied in combination with oxygen nonstoichiometry (δ) at 298-1223 K and p(O2) = 10â4 to 1.00 atm. In order to minimize the effects of phase separation or oxygen-vacancy ordering processes, the data were collected in dynamic cooling mode using dense ceramic samples. The procedure was justified by a very fast equilibration at given p(O2) in high-temperature range demonstrated for ceramics samples with different specific surface area. The difference in nonstoichiometry of BSCF and SCF at temperatures â¥973 K was found to be â¤0.03 oxygen atoms per formula unit. BSCF demonstrates favorably smaller chemical expansion compared to SCF and many other mixed conductors, originating from smaller δ variations and larger unit cell less sensitive to temperature and nonstoichiometry changes. Excessive thermochemical expansion impedes however the use of BSCF in single-phase fuel cell cathodes and planar mixed-conducting membranes.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
A.A. Yaremchenko, S.M. Mikhalev, E.S. Kravchenko, J.R. Frade,