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arXiv · 2504.19603

Magnetic order and Li-diffusion in the 1/3-filled Kagome layers of antiperovskite Lithium-ion battery materials (Li$_2$Fe)SO and (Li$_2$Fe)SeO

F. Seewald·T. Schulze·N. Gräßler·F. L. Carstens·L. Singer·M. A. A. Mohamed·S. Hampel·B. Büchner·R. Klingeler·H. -H. Klauss·H. -J. Grafe
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Abstract

The recently discovered lithium-rich antiperovskites (Li$_2$Fe)SeO and (Li$_2$Fe)SO host lithium and iron ions on the same atomic position which octahedrally coordinates to central oxygens. In a cubic antiperovskite these sites form Kagome planes stacked along the <111> directions which triangular motifs induce high geometric frustration in the diluted magnetic sublattice for antiferromagnetic interactions. Despite their compelling properties as high-capacity Li-ion battery cathode materials, very little is known about the electronic and magnetic properties of lithium-rich antiperovskites. We report static magnetization, M\"ossbauer, and NMR studies on both compounds. Our data reveal a Pauli paramagnetic-like behaviour, a long-range antiferromagnetically ordered ground state below 50 K and a regime of short-range magnetic correlations up to 100 K. Our results are consistent with a random Li-Fe distribution on the shared lattice position. In addition, Li-hopping is observed above 200 K with an activation energy of E$_a$ = 0.47 eV. Overall, our data elucidate static magnetism in a disordered magnetically frustrated and presumably semimetallic system with thermally induced ion diffusion dynamics.

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F. Seewald, T. Schulze, N. Gräßler, F. L. Carstens, L. Singer, M. A. A. Mohamed, S. Hampel, B. Büchner, R. Klingeler, H. -H. Klauss, H. -J. Grafe. 2025-04-28. Magnetic order and Li-diffusion in the 1/3-filled Kagome layers of antiperovskite Lithium-ion battery materials (Li$_2$Fe)SO and (Li$_2$Fe)SeO. https://doi.org/10.1103/t7tf-5ntl

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