Oxygen permeation and stability of La_0.6Sr_0.4Ti_xFe_1-xO_3-δ (x = 0.2 and 0.3) membrane

An oxygen transport ceramic membrane was prepared with La_0.6Sr_0.4Ti_xFe_1-xO_3-δ (x = 0.2 and 0.3) oxides which was synthesized by polymerized complex method. In order to investigate the effects of Ti substitutions into lanthanum-strontium ferrites, material property, thermal expansion coefficient, oxygen permeation, electrical conductivity and phase stability were examined according to Ti contents. The thermal expansion coefficients of LSTF6428 and LSTF6437 were 25.76 × 10^-6 K^-1 and 21.32 × 10^-6 K^-1 in the temperature range of 973-1273 K, respectively. The oxygen permeation fluxes through a disk type dense membrane of LSTF6428 and LSTF6437 with 1.6 mm thickness increased exponentially with increasing temperature and were 0.17 mL min^-1cm^-2 and 0.13 mL min^-1cm^-2 with P_h = 0.21 atm (O₂ rich side) and P_l = 10^-5 atm (lean side) at 1223 K, respectively. In the result of phase stability test with various conditions such as He, H₂/N₂ and CO₂ atmosphere, La_0.6Sr_0.4Ti_xFe_1-xO_3-δ was confirmed to be more stable than La_0.6Sr_0.4Ti_0.2Fe_0.8O_3-δ through XRD and SEM analysis.