Tailoring the Anisotropic Oxygen Transport Properties in Bulk Ceramic Membranes Based on a Ruddlesden–Popper Oxide by Applying Magnetic Fields

Textured Nd₂NiO₄₊ _δ bulk ceramic membranes are fabricated via slip casting in a 0.9 T magnetic field generated by neodymium magnets. This process aligns the oxide grains with their easy-magnetization c-axis parallel to the applied magnetic field. Depending on the magnetic field's direction relative to the slip casting, grains orient either with their a,b-plane or c-axis parallel to the normal direction of the disk-shaped ceramic, thus aligning with the oxygen permeation direction. Without the magnetic field, a non-textured bulk membrane is formed. The microstructure and texture of the ceramic membranes are meticulously analyzed using advanced techniques, including X-ray diffraction, scanning and transmission electron microscopy, as well as related methods. Evaluation of the texturing effect on the oxygen permeation performance shows that the a,b-plane textured Nd₂NiO₄₊ _δ bulk membrane achieves the highest oxygen permeation fluxes between 1023-1223 K. Additionally, it demonstrates impressive CO₂ stability, maintaining effective performance for at least 140 h due to preferential oxygen transport along the a,b-plane. These characteristics make Nd₂NiO₄₊ _δ an auspicious material for industrial applications as an oxygen transport membrane, outperforming more susceptible perovskite-based materials. Magnetic alignment thus proves to be an effective method for achieving membrane texturing, enabling precise regulation of oxygen transport properties.