Wissel, Kerstin ; Heldt, Jonas ; Groszewicz, Pedro B. ; Dasgupta, Supratik ; Breitzke, Hergen ; Donzelli, Manuel ; Waidha, Aamir I. ; Fortes, Andrew Dominic ; Rohrer, Jochen ; Slater, Peter R. ; Buntkowsky, Gerd ; Clemens, Oliver (2018)
Topochemical Fluorination of La2NiO4+d: Unprecedented Ordering of Oxide and Fluoride Ions in La2NiO3F2.
In: Inorganic Chemistry, 57 (11)
doi: 10.1021/acs.inorgchem.8b00661
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Synopsis
La2NiO3F2 crystallizes in a new anion-ordered distortion variant of the n = 1 Ruddlesden−Popper-type structure. The unprecedented ordering of oxygen anions in the interlayer leads to an expansion of the lattice perpendicular to the stacking direction, accompanied by a strong tilting of NiO4F2 octahedra. A weakening of Ni−F−F−Ni superexchange interactions between the perovskite-type layers due to the reduced covalency of fluoride ions decreases the magnetic ordering temperature strongly.
Abstract The Ruddlesden–Popper (K2NiF4) type phase La2NiO3F2 was prepared via a polymer-based fluorination of La2NiO4+d. The compound was found to crystallize in the orthorhombic space group Cccm (a = 12.8350(4) Å, b = 5.7935(2) Å, c = 5.4864(2) Å). This structural distortion results from an ordered half occupation of the interstitial anion layers and has not been observed previously for K2NiF4-type oxyfluoride compounds. From a combination of neutron and X-ray powder diffraction and 19F magic-angle spinning NMR spectroscopy, it was found that the fluoride ions are only located on the apical anion sites, whereas the oxide ions are located on the interstitial sites. This ordering results in a weakening of the magnetic Ni–F–F–Ni superexchange interactions between the perovskite layers and a reduction of the antiferromagnetic ordering temperature to 49 K. Below 30 K, a small ferromagnetic component was found, which may be the result of a magnetic canting within the antiferromagnetic arrangement and will be the subject of a future low-temperature neutron diffraction study. Additionally, density functional theory-based calculations were performed to further investigate different anion ordering scenarios.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2018 |
| Autor(en): | Wissel, Kerstin ; Heldt, Jonas ; Groszewicz, Pedro B. ; Dasgupta, Supratik ; Breitzke, Hergen ; Donzelli, Manuel ; Waidha, Aamir I. ; Fortes, Andrew Dominic ; Rohrer, Jochen ; Slater, Peter R. ; Buntkowsky, Gerd ; Clemens, Oliver |
| Art des Eintrags: | Bibliographie |
| Titel: | Topochemical Fluorination of La2NiO4+d: Unprecedented Ordering of Oxide and Fluoride Ions in La2NiO3F2 |
| Sprache: | Englisch |
| Publikationsjahr: | 4 Juni 2018 |
| Verlag: | ACS Publications |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Inorganic Chemistry |
| Jahrgang/Volume einer Zeitschrift: | 57 |
| (Heft-)Nummer: | 11 |
| DOI: | 10.1021/acs.inorgchem.8b00661 |
| URL / URN: | https://doi.org/10.1021/acs.inorgchem.8b00661 |
| Kurzbeschreibung (Abstract): | Synopsis La2NiO3F2 crystallizes in a new anion-ordered distortion variant of the n = 1 Ruddlesden−Popper-type structure. The unprecedented ordering of oxygen anions in the interlayer leads to an expansion of the lattice perpendicular to the stacking direction, accompanied by a strong tilting of NiO4F2 octahedra. A weakening of Ni−F−F−Ni superexchange interactions between the perovskite-type layers due to the reduced covalency of fluoride ions decreases the magnetic ordering temperature strongly. Abstract The Ruddlesden–Popper (K2NiF4) type phase La2NiO3F2 was prepared via a polymer-based fluorination of La2NiO4+d. The compound was found to crystallize in the orthorhombic space group Cccm (a = 12.8350(4) Å, b = 5.7935(2) Å, c = 5.4864(2) Å). This structural distortion results from an ordered half occupation of the interstitial anion layers and has not been observed previously for K2NiF4-type oxyfluoride compounds. From a combination of neutron and X-ray powder diffraction and 19F magic-angle spinning NMR spectroscopy, it was found that the fluoride ions are only located on the apical anion sites, whereas the oxide ions are located on the interstitial sites. This ordering results in a weakening of the magnetic Ni–F–F–Ni superexchange interactions between the perovskite layers and a reduction of the antiferromagnetic ordering temperature to 49 K. Below 30 K, a small ferromagnetic component was found, which may be the result of a magnetic canting within the antiferromagnetic arrangement and will be the subject of a future low-temperature neutron diffraction study. Additionally, density functional theory-based calculations were performed to further investigate different anion ordering scenarios. |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Dünne Schichten 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Materialdesign durch Synthese 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Materialmodellierung 07 Fachbereich Chemie 07 Fachbereich Chemie > Eduard Zintl-Institut > Fachgebiet Physikalische Chemie |
| Hinterlegungsdatum: | 11 Dez 2018 15:01 |
| Letzte Änderung: | 11 Dez 2018 15:01 |
| PPN: | |
| Sponsoren: | his work was funded by the German Research Foundation within the Emmy Noether program (Grant No. CL551/2-1)., Neutron diffraction beam time on HRPD at ISIS was provided by the Science and Technology Facilities Council (No. 1720040)., Computational time was made available at the Lichtenberg-Cluster at TU Darmstadt, Germany. |
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