Multiplying Oxygen Permeability of a Ruddlesden-Popper Oxide by Orientation Control via Magnets.

Ruddlesden-Popper-type oxides exhibit remarkable chemical stability in comparison to perovskite oxides. However, they display lower oxygen permeability. We present an approach to overcome this trade-off by leveraging the anisotropic properties of Nd ₂ NiO _4+δ . Its (a,b)-plane, having oxygen diffusion coefficient and surface exchange coefficient several orders of magnitude higher than its c-axis, can be aligned perpendicular to the gradient of oxygen partial pressure by a magnetic field (0.81 T). A stable and high oxygen flux of 1.40 mL min ^-1  cm ^-2 was achieved for at least 120 h at 1223 K by a textured asymmetric disk membrane with 1.0 mm thickness under the pure CO ₂ sweeping. Its excellent operational stability was also verified even at 1023 K in pure CO ₂ . These findings highlight the significant enhancement in oxygen permeation membrane performance achievable by adjusting the grain orientation. Consequently, Nd ₂ NiO _4+δ emerges as a promising candidate for industrial applications in air separation, syngas production, and CO ₂ capture under harsh conditions.
(© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)