Topochemical Reduction of La2NiO3F2: The First Ni-Based Ruddlesden–Popper n = 1 T′-Type Structure and the Impact of Reduction on Magnetic Ordering

• DOI: 10.1021/acs.chemmater.0c00193
• Publication Date: 2020-02-06T20:07:36Z
• Authors: Kerstin Wissel; Ali Muhammad Malik; Sami Vasala; Sergi Plana-Ruiz; Ute Kolb; Peter R. Slater; Ivan da Silva; Lambert Alff; Jochen Rohrer; Oliver Clemens
• Keywords: Superexchange; Non-blocking I/O; Stoichiometry; Magnetic structure

Within this study, we show that a broad range of reduced phases La2NiO3F2−Δ can be derived from Ruddlesden–Popper-type La2NiO3F2 using reductive topochemical defluorination method based on reactions between the oxyfluoride and sodium hydride. The selective extraction fluoride results in strong structural changes, nuclear magnetic structures obtained have been determined. Due to high anion content La2NiO3F2, formation Ni+-containing compounds has observed under reduction. For first time, led highest end member with T′-type structure an approximate composition La2NiO3F n = 1 series containing only Ni+ as B-cation. This compound described stacking alternating (La/O2/La) fluorite-type layers Lan–1(NiO2)n infinite layer blocks. underlying reaction mechanism investigated by means X-ray neutron diffraction, elemental analysis, measurements. Furthermore, gain deeper understanding distortions, density functional theory-based calculations were performed, providing information about rearrangements upon interactions. It is highlighted presence even small amounts d9-configured cations leads changes La2NiO3F1.93, introducing long-range antiferromagnetic ordering adjacent perovskite building blocks increasing Ni–X–X–Ni super-superexchange interactions compared stoichiometric La2NiO3F2.