La x Sr1–x Co1–y Fe y O3 (LSCF) is a promising material for intermediate temperature solid oxide fuel cell (IT-SOFC) cathodes. The fabrication of LSCF cathodes composed of fibers might enhance SOFC dispositive currents due to facilitating gas permeability through a porous structure. In the present work, La0.6Sr0.4Co1–y Fe y O3 (y = 0.2–1.0) fibers were obtained by electrospinning, and the structure and electrical properties were investigated. 1 μm wide LSCF fibers were obtained after the electrospun fibers were thermal treated at 1000 °C to remove the polymer and form the crystalline perovskite materials. The electrical conductivity of LSCF fibers as a function of temperature was measured using 2-point and 4-point probe methodologies for all compositions prepared, and the associate charge carrier activation energies were calculated using the Arrhenius model. The electrical conductivity increases with an increase in temperature from room temperature to 700 °C; this suggests a predominant small-polaron hopping mechanism. Above 700 °C, the LSCF fibers show a semiconductor-metal transition, and the electrical conductivity decreases.

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Thick nanoporous oxide films exhibiting interference colors were grown on AISI 304L stainless steel by triangular current scan method in 5 M H2SO4 + 2.5 M H2CrO4 using different electrolysis times. The nanocrystalline spinel oxide films thus obtained were electrochemically characterized by cyclic voltammetry at 1 mV•s-1 in 0.5 M Na2SO4. Strong anodic peaks are observed at the potential region where the transpassive peak of stainless steels is expected. Such behavior evidences not only the large active surface area of the films, but also that the cationic species are not fully oxidized. The effect of polarizing in 0.5 M Na2SO4 to a potential in the transpassive region on the morphology and the composition of these films was investigated.