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

Wissel, Kerstin and Malik, Ali Muhammad and Vasala, Sami and Plana-Ruiz, Sergi and Kolb, Ute and Slater, Peter R. and da Silva, Ivan and Alff, Lambert and Rohrer, Jochen and Clemens, Oliver (2020):
Topochemical Reduction of La2NiO3F2: The First Ni-Based Ruddlesden–Popper n = 1 T′-Type Structure and the Impact of Reduction on Magnetic Ordering.
In: Chemistry of Materials, 32 (7), pp. 3160-3179. ACS Publications, ISSN 0897-4756,
DOI: 10.1021/acs.chemmater.0c00193,
[Article]

Abstract

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

Item Type: Article
Erschienen: 2020
Creators: Wissel, Kerstin and Malik, Ali Muhammad and Vasala, Sami and Plana-Ruiz, Sergi and Kolb, Ute and Slater, Peter R. and da Silva, Ivan and Alff, Lambert and Rohrer, Jochen and Clemens, Oliver
Title: Topochemical Reduction of La2NiO3F2: The First Ni-Based Ruddlesden–Popper n = 1 T′-Type Structure and the Impact of Reduction on Magnetic Ordering
Language: English
Abstract:

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

Journal or Publication Title: Chemistry of Materials
Journal volume: 32
Number: 7
Publisher: ACS Publications
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Earth Science
11 Department of Materials and Earth Sciences > Earth Science > Geo-Material-Science
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Advanced Thin Film Technology
11 Department of Materials and Earth Sciences > Material Science > Fachgebiet Materialdesign durch Synthese
11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
Date Deposited: 29 Apr 2020 07:02
DOI: 10.1021/acs.chemmater.0c00193
Official URL: https://doi.org/10.1021/acs.chemmater.0c00193
Projects: This work was funded by the German Research Foundation within the Emmy Noether program (grant no. CL551/2-1)., K.W. acknowledges funding from the JUICED Hub (EPSRC grant no. EP/R023662/1) researcher mobility fund., Neutron diffraction beam time on GEM at ISIS was provided by the Science and Technology Facilities Council (STFC) (grant no. RB1820423).
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