Properties of novel Al₂O₃-doped SrCo_0.8Fe_0.2O_3-δ mixed conducting oxides

A series of Al₂O₃-doped SrCo_0.8Fe_0.2O_3-δ (SCFA) mixed conducting oxides were synthesized by the solid-state reaction method. XRD and TG were used to characterize the crystal structure and oxygen nonstoichiometry of the SCFA. The oxygen permeation processes and stability of the SCFA membrane were investigated by high temperature oxygen permeation measurement and thermal decomposition of carbon dioxide (TDCD) coupled with partial oxidation of methane (POM) to syngas. When the doping amount of Al₂O₃ was lower than 3% (mass), Al³⁺ cations were found to diffuse into the interstitial sites of SrCo_0.8Fe_0.2O_3-δ (SCF) lattice, which greatly enhanced the structure stability of the materials synthesized. Both the bulk diffusion and surface exchange processes affected the oxygen permeation in SCFA3 [the doping amount of Al₂O₃ was 3% (mass)], and the characteristic thickness (L_c) of SCF A3 was about 131.5 μm. TDCD-POM reaction (1173 K) indicated that the stability of the Al₂O₃-doped SrCo_0.8Fe_0.2O_3-δ was better than that of the ZrO₂-doped SrCo_0.4Fe_0.6O_3-δ (SCFZ).