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Stabilization of a Complex Perovskite Superstructure under Ambient Conditions: Influence of Cation Composition and Ordering, and Evaluation as an SOFC Cathode

DOI: 10.1021/cm102475n DOI Help

Authors: A. Demont (University of Liverpool) , M. S. Dyer (University of Liverpool) , R. Sayers (University of Liverpool) , M. F. Thomas (University of Liverpool) , M. Tsiamtsouri (University of Liverpool) , H. N. Niu (University of Liverpool) , G. R. Darling (University of Liverpool) , A. Daoud-aladine (ISIS Facility) , J. B. Claridge (University of Liverpool) , M. J. Rosseinsky (University of Liverpool)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry Of Materials , VOL 22 (24) , PAGES 6598–6615

State: Published (Approved)
Published: December 2010

Open Access Open Access

Abstract: Ba1.6Ca2.3Y1.1Fe5O13 is an Fe3+ oxide adopting a complex perovskite superstructure, which is an ordered intergrowth between the Ca2Fe2O5 and YBa2Fe3O8 structures featuring octahedral, square pyramidal, and tetrahedral B sites and three distinct A site environments. The distribution of A site cations was evaluated by combined neutron and X-ray powder diffraction. Consistent with the Fe3+ charge state, the material is an antiferromagnetic insulator with a Nel temperature of 480−485 °C and has a relatively low d.c. conductivity of 2.06 S cm−1 at 700 °C. The observed area specific resistance in symmetrical cell cathodes with the samarium-doped ceria electrolyte is 0.87 Ω cm2 at 700 °C, consistent with the square pyramidal Fe3+ layer favoring oxide ion formation and mobility in the oxygen reduction reaction. Density functional theory calculations reveal factors favoring the observed cation ordering and its influence on the electronic structure, in particular the frontier occupied and unoccupied electronic states.

Subject Areas: Chemistry

Instruments: I11-High Resolution Powder Diffraction