Synthesis and Characterization of La[sub 0.6]Sr[sub 0.4]Co[sub 0.2]Fe[sub 0.8]O[sub 3−δ] and Ba[sub 0.5]Sr[sub 0.5]Co[sub 0.8]Fe[sub 0.2]O[sub 3−δ]

Abstract

This study compares the electrical transport and the oxygen exchange properties of two mixed conducting materials between 600 and 800°C, namely La<SUB>0.6</SUB>Sr<SUB>0.4</SUB>Co<SUB>0.2</SUB>Fe<SUB>0.8</SUB>O<SUB>3−δ</SUB> (LSCF) and Ba<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Co<SUB>0.8</SUB>Fe<SUB>0.2</SUB>O<SUB>3−δ</SUB> (BSCF). Both materials were synthesized by spray pyrolysis and characterized by the electrical conductivity relaxation technique. LSCF has the higher electrical conductivity (257–412 S cm<SUP>−1</SUP> between 450 and 900°C), while BSCF shows faster oxygen exchange kinetics and diffusion. The expansion of both materials between 600 and 800°C (BSCF=27.3 ppm/K, LSCF=15.5 ppm/K below 700°C up to 27.5 ppm/K at <I>T</I>>800°C) does not match with the common electrolytes for solid oxide fuel cells.