In situ diffraction studies on reversible oxygen uptake and release in AFe₂O_{4 + δ} (A= Lu, Yb, Y, and In)

Abstract

We have studied the reversible uptake and release of oxygen in the layered metal oxide system AB2O4 for A = Lu, Yb, Y, and In to understand their suitability as oxygen storage materials.

Crystal field-induced lattice expansion upon reversible oxygen uptake/release in YbMnxFe2−xO4

“…Measurements were performed in transmission geometry using gas filled ion chambers as detectors on powder samples diluted with boron nitride and pressed into pellets. successfully fitted the major Bragg peaks with symmetry model, which is reported to be the 𝑃3 average crystal structure of unsubstituted YbFe 2 O 4.5 22,23 (Figure 1b). The final refined structural and lattice parameters are shown in Table S2.…”

“…As a potential oxygen storage material, volume change before and after oxygen release/uptake is a key metric. Large volume expansion and contraction of the material during the cycling can lead to severe mechanical failure of the containers or reactors 56 elsewhere 22,23 for comparison.…”

“…However, other ternary metal oxides besides the perovskites also show promise in the field of OSMs. The hexagonal layered oxide LnFe 2 O 4, where Ln is a lanthanide cation, and related hexagonal AB 2 O 4 materials have recently drawn attention as potential OSMs [21][22][23] . The crystal structure of LnFe 2 O 4, given in Figure 1a, usually adopts symmetry 24 and consists of 𝑅3𝑚 alternating layers of edge-sharing LnO 6 octahedra and edge-sharing FeO 5 trigonal bipyramids.…”

CaCoxZr1−xO3−δ Perovskites as Oxygen‐Selective Sorbents for Air Separation

“…At high temperatures and under a chemical‐potential gradient, perovskites can reversibly store and release oxygen ions, which diffuse through the crystal lattice by hopping on/off oxygen‐vacancy defect sites . Sorbent and membranes based on these type of materials have a very high selectivity (>99 %) for oxygen over nitrogen or other non‐oxygen gas species . However, the challenge remains to improve material performance by increasing oxygen‐sorption capacity and simultaneously reducing operating temperatures to enable their effective use in air separation process …”

“…[9] Sorbenta nd membranes based on these type of materials have av ery high selectivity (> 99 %) for oxygen over nitrogen or other non-oxygen gas species. [13,14] However, the challenge remains to improvem aterial performance by increasing oxygen-sorption capacity and simultaneously reducing operating temperatures to enable their effective use in air separationprocess. [1]…”