Abstract

Perovskites of composition SrFe1-xScxO3-delta(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 degrees C, the crystallographic structure of SrFe(0.9)Sc(0.1)O(3-delta)contains delta = 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 sigma exhibits an insulator-to-metal transition at 420 degrees C, reaching almost 200 S cm(-1)for x = 0.05; sigma 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 H-2. The maximum power density reached by the Sc-ferrite (x = 0.05) was of 340 mW cm(-2)at 800 degrees C.