Preparation of Asymmetric Tubular Oxygen Separation Membrane with Oxygen Permeable Pr ₂ Ni _0.75 Cu _0.25 Ga _0.05 O _4+δ

The electrical conductivities and oxygen permeation properties of Pr ₂ Ni _0.75 Cu _0.25 Ga _0.05 O _4+δ were measured by conventional DC four‐probe method with Pt electrode and gas chromatography. The total conductivities increased with an apparent slope of 1/6, satisfied by the charge neutrality condition at the p ‐type regime of . A tubular‐type, asymmetric, mixed‐conducting oxygen separation membrane was fabricated by drain casting method. A microporous, ceramic support was prepared by slurry processing, because the use of a slurry technique and a suspension of dispersed particles provides a lower final porosity and a more homogeneous particle packing than dry‐pressing does. The 30 cm long, tubular, porous alumina with a soft surface was successfully prepared by drain casting. The surface SEM images revealed a structure with reasonable porosity and well‐necked particles. A mixed‐conducting layer of Pr ₂ Ni _0.75 Cu _0.25 Ga _0.05 O _4+δ was applied inside of the support tube by drain casting. A dense separation layer was successfully fabricated inside the porous alumina tube by sintering at 1473 K for 8 h in air.