Dense perovskite-structured membranes with desired composition of La0.8Sr0.2Co0.6Fe0.4O3
-
δ
(LSCF) were prepared from powders produced by four different methods. LSCF powders prepared
by citrate, solid-state, and spray−pyrolysis methods had compositions close to the desired
stoichiometry with a slight difference in cobalt concentration, whereas coprecipitated powders
had a large strontium deficiency. The membrane composition was a determining factor that
affected the electronic conductivity and therefore oxygen permeability. The membrane with a
large strontium deficiency had much lower electronic conductivity and oxygen permeability (ionic
conductivity) than the other three membranes with compositions close to the desired stoichiometry. The electronic conductivity of membranes prepared from citrate, solid-state, and spray−pyrolysis methods increases with the cobalt concentration of the membrane. For the three
membranes with similar composition, the activation energy of oxygen flux decreases with
increasing grain size. Oxygen pressure dependency of oxygen vacancy concentration is also
influenced by the membrane microstructure and composition. LSCF membranes with same
composition and similar microstructure should have similar electric and oxygen transport
properties.
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