Electric Transport and Oxygen Permeation Properties of Lanthanum Cobaltite Membranes Synthesized by Different Methods

• Published in: Industrial & engineering chemistry research Vol. 39; no. 3; pp. 646 - 653
• Main Authors: Qi, Xiwang, Lin, Y. S, Swartz, S. L
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.03.2000
• Subjects: CHEMICAL PREPARATION; Chemistry; COBALT OXIDES; Colloidal state and disperse state; ELECTRIC CONDUCTIVITY; ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; Exact sciences and technology; General and physical chemistry; IONIC CONDUCTIVITY; IRON OXIDES; LANTHANUM OXIDES; MATERIALS SCIENCE; MEMBRANES; MICROSTRUCTURE; STRONTIUM OXIDES; Scanning electron microscopy; Oxygen; Electrical conductivity; Cobalt Oxides; Perovskite type compound; Electrical properties; Lanthanum Oxides; Temperature effect; Experimental study; Inductive coupling plasma spectrometry; X ray diffraction; Oxide ceramics; Multi-element compound; Characterization; Iron Oxides; Gas permeability; Pressure effect; Flux density; Preparation; Strontium Oxides; Inorganic membrane
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie990675e

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.