Abstract

Perovskites of composition SrFe1-xScxO3-δ (x = 0.05, 0.1, 0.2) were elaborated, characterized, and tested in solid-oxide fuel cells (SOFC) as cathode materials. Porous materials were obtained by a solid-state route. Thermogravimetric studies showed that the oxides eliminate oxygen as temperature increases. Neutron powder diffraction (NPD) experiments unveils that, at 800°C, the crystallographic structure of SrFe0.9Sc0.1O3-δ contains δ = 0.51 (2) vacancies at oxygen sites, located at random in the cubic unit cell. The oxygen vacancies are essential for the oxygen diffusion, which is prerequisite for a MIEC-type cathode. The electronic conductivity σ exhibits an insulator-to-metal transition at 420°C, reaching almost 200 S cm−1 for x = 0.05; σ was found to decrease as the Sc content increases. The cell performance was tested on electrolyte supported single cells, with LSGM electrolyte, fed by pure H2. The maximum power density reached by the Sc-ferrite (x = 0.05) was of 340 mW cm−2 at 800°C.