Thermal expansion, microhardness and oxygen permeation of La_1-xSr_xCo_0.8Fe_0.2O_3+δ membranes

Dense ceramic membranes acting as oxygen and electron ion-conductors can be used as the catalysts for syngas production. The La_1-xSr_xCo_0.8Fe_0.2O_3+δ (LSCF) systems were known to have a high ionic and electronic conductivity. In the application, the La_1-xSr_xCo_0.8Fe_0.2O_3+δ membranes required low thermal expansion, microhardness and high oxygen permeation flux. The changes in the expansion, hardness, and oxygen flux of the La_1-xSr_xCo_0.8Fe_0.2O_3+δ perovskite membranes with various strontium substitutions were studied. The magnitude of both the thermal expansion and the oxygen content of the La_1-xSr_xCo_0.8Fe_0.2O_3+δ membranes decreased with up to 20 % strontium substitution and then increased with 30 and 40 % strontium ion substitution. Meanwhile, the hardness and shrinkage improved by various strontium ion substitutions, except with 20 % strontium. The highest oxygen flux over La_1-xSr_xCo_0.8Fe_0.2O_3+δ (0.0 ≤ x ≤ 0.4) membranes in the surface exchange-controlled processes was found of the membrane with 30 % strontium substitution.