Mechanical strength, and oxygen and electronic transport properties of SrCo_0.4Fe_0.6O_3-δ-YSZ membranes

Three membranes including SrCo_0.4Fe_0.6O_3-δ (SCF), 9wt.% yttria-stabilized zirconia (YSZ) doped SrCo_0.4Fe_0.6O_3-δ (9%YSZ-SCF), 40wt.% YSZ doped SrCo_0.4Fe_0.6O_3-δ (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 opposite order. In 950-1050K, oxygen vacancy concentration variation of the 9%YSZ-SCF membrane is higher than that of the SCF membrane due to the special effect of the doping YSZ. The oxygen permeation flux increases with temperature, and decreases with thickness. Doping the membrane with 9wt.% YSZ does not influence the oxygen permeability significantly because both the ionic and the electronic conductivities remain high. In situ high-temperature X-ray diffraction (HTXRD) analysis indicates the 9%YSZ-SCF membrane is more stable than the SCF membrane at high temperatures under a low oxygen partial pressure.