Effect of the size and amount of ZrO₂ addition on properties of SrCo_0.4Fe_0.6O_3-δ

The effects of ZrO₂ addition with various particle sizes (1, 3, and 56 μm) and various amounts (0, 1, 3, 5, 7, 9 wt. %) on structure, oxygen permeation, and stability of SrCo_0.4Fe_0.6O _3-δ (SCF) were investigated. XRD and EDX analysis revealed that the dissolution of Zr cation into the B site of SCF phase occurred with the addition of ZrO₂, resulting in a lattice expansion of SCF at elevated temperatures. The dissolution amount of Zr in the SCF phase increased with a decrease of ZrO₂ particle size and an increase in the amount of ZrO₂ added, and, therefore, resulted in a decrease of oxygen permeation flux of the membranes and an increase in their structural stability in a helium atmosphere. This study indicated that adding a certain amount of Zr cation in SCF oxide was an effective route to sustain the structural stability of SCF in low oxygen partial pressure, and the optimum ZrO₂ addition was 3 wt.% with a particle size of 1 μm, which greatly improved the structural stability without significantly changing the oxygen permeability of SCF.