title: Unveiling structure-property relationships in Sr2Fe(1.5)Mo(0.5)O(6-δ), an electrode material for symmetric solid oxide fuel cells.
abstract: We characterize experimentally and theoretically the promising new solid oxide fuel cell electrode material Sr(2)Fe(1.5)Mo(0.5)O(6-δ) (SFMO). Rietveld refinement of powder neutron diffraction data has determined that the crystal structure of this material is distorted from the ideal cubic simple perovskite, instead belonging to the orthorhombic space group Pnma. The refinement revealed the presence of oxygen vacancies in the as-synthesized material, resulting in a composition of Sr(2)Fe(1.5)Mo(0.5)O(5.90(2)) (δ = 0.10(2)). DFT+U theory predicts essentially the same concentration of oxygen vacancies. Theoretical analysis of the electronic structure allows us to elucidate the origin of this nonstoichiometry and the attendant mixed ion-electron conductor character so important for intermediate temperature fuel cell operation. The ease with which SFMO forms oxygen vacancies and allows for facile bulk oxide ion diffusivity is directly related to a strong hybridization of the Fe d and O p states, which is also responsible for its impressive electronic conductivity.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Program in Applied and Computational Mathematics, and Gerhard R. Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Ana B
authors.initials: AB
authors.lastname: Muñoz-García
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Bugaris
authors.forename: Michele
authors.initials: M
authors.lastname: Pavone
authors.forename: Jason P
authors.initials: JP
authors.lastname: Hodges
authors.forename: Ashfia
authors.initials: A
authors.lastname: Huq
authors.forename: Fanglin
authors.initials: F
authors.lastname: Chen
authors.forename: Hans-Conrad
authors.initials: HC
authors.lastname: zur Loye
authors.forename: Emily A
authors.initials: EA
authors.lastname: Carter