Mechanical strength, and oxygen and electronic transport properties of SrCo0.4Fe0.6O3-delta-YSZ membranes

Three membranes including SrCo0.4Fe0.6O3-delta (SCF), 9 wt.% yttria-stabili zed zirconia (YSZ) doped SrCo0.4Fe0.6O3-delta (9%YSZ-SCF), 40 wt.% YSZ dope d SrCo0.4Fe0.6O3-delta (40%YSZ-SCF) were prepared. The dual-phase composite , 9%YSZ-SCF, consists of mainly perovskite type and SrZrO3. The electronic conductivity of the three composites increases in the order of 40%YSZ-SCF < 9%YSZ-SCF < SCF. The magnitude of mechanical strength increases in the opp osite order. In 950-1050 K, oxygen vacancy concentration variation of the 9 %YSZ-SCF membrane is higher than that of the SCF membrane due to the specia l effect of the doping YSZ. The oxygen permeation flux increases with tempe rature, and decreases with thickness. Doping the membrane with 9 wt.% YSZ d oes not influence the oxygen permeability significantly because both the io nic and the electronic conductivities remain high. In situ high-temperature X-ray diffraction (HTXRD) analysis indicates the 9%YSZ-SCF membrane is mor e stable than the SCF membrane at high temperatures under a low oxygen part ial pressure. (C) 2001 Elsevier Science B.V. All rights reserved.