Structural and microstructural characterization and properties of new phases in the Nd–Sr–Co–(Fe/Mn)–O system as air-electrodes in SOFCs

Abstract

New oxides of the (NdSr)MO (M = Co and Mn or Fe) series are reported. Compounds of composition NdSrCoFeO, NdSrCoMnO and NdSrCoMnO are the n = 1 members of the Ruddlesden-Popper homologous series (KNiF structural type) as determined by X-ray diffraction and different transmission electron microscopy techniques. Their crystal structure consists of connected (Co-Fe/Mn)O octahedra blocks separated by (Nd/Sr)O rock-salt like layers along the c-axis. Interstitial oxygen atoms or anion vacancies are induced depending on composition. Oxides with interstitial oxygen show good performances as intermediate temperature solid oxide fuel cell (IT-SOFC) cathode. The area-specific resistance values of electrodes made of these oxides at 973 K in air are 0.18 Ω cm for NdSrCoFeO and NdSrCoMnO (comparable to the one of the state-of-the-art materials proposed as cathodes in IT-SOFC), and 1.38 Ω cm for NdSrCoMnO.

Defect Chemistry, Electrical Properties, and Evaluation of New Oxides Sr2CoNb1−xTixO6−δ (0≤x≤1) as Cathode Materials for Solid Oxide Fuel Cells

“…At 973 K, an ASR value of 0.12 Ω cm 2 is similar to those of the best compounds reported so far: SrNdCo 0.75 Fe 0.25 O 4.08 and SrNdCo 0.75 Mn 0.25 O 4.08 (ca. 0.18 Ω cm 2 in both cases at 973 K), and similar values at 1073 K for La 4 Ni 2.6 Co 0.4 O 10+ δ and NdSrCoO 4+ δ The better performance of the x= 1 member of the series is mainly owing to higher conductivity, which favors both electronic‐charge transfer and oxidation/reduction processes.…”

Superior Performance as Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cells of the Ruddlesden–Popper n = 2 Member Eu2SrCo0.50Fe1.50O7−δ with Low Cobalt Content

“…In the search for cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFC), oxides of the Ruddlesden–Popper (R–P) family are attracting much attention. − The R–P series, , with the general formula A n +1 M n O 3 n +1 ((AMO 3 ) n AO) (A = rare-earth and/or alkaline-earth elements and M = transition metal with n = 1, 2, etc. ), comprise a vast family of oxides.…”