Comparison of the Effect Cations La, Sr, and Ba on Oxygen Permeation Through A-Sr-Co-Fe (A: La, Ba, and Sr) Perovskite Membranes

Perovskite dense membranes of La0.6Sr0.4Co0.8Fe0.2O3−δ (LSCF), Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and SrCo0.8Fe0.2O3-δ(SCF) were prepared by complexation method with EDTA-citrate. The perovskite phase structure of the samples was characterized by X-ray diffraction and experimental formula and stoichiometry of the metal ions for the prepared perovskite were confirmed by atomic absorption spectroscopy and inductively coupled plasma. The oxygen permeation flux through the perovskite dense membranes was measured and optimized by change in oxygen partial pressure, temperature, membrane thickness, and the used composition in perovskite structure. The oxygen permeation flux was measured in the range of temperature within 1073–1223 K and the partial pressure of 0.1–1.0 bar. The flux increases in the order of LSCF < SCF< BSCF membranes and the calculations of crystallography parameters such as lattice energy and free volume can confirm this point. The linear changes of oxygen flux versus ln(P2/P1) states that bulk diffusion through the membrane is the rate-limiting step.