Abstract
We combine powder neutron diffraction, magnetometry and 57Fe Mössbauer spectrometry to determine the nuclear and magnetic structures of a strongly interacting weberite-type inorganic-organic hybrid fluoride, Fe2F5(Htaz). In this structure, Fe2+ and Fe3+ cations form magnetically frustrated hexagonal tungsten bronze (HTB) layers of corner sharing octahedra. Our powder neutron diffraction data reveal that, unlike its purely inorganic fluoride weberite counterparts which adopt a centrosymmetric Imma structure, the room- temperature nuclear structure of Fe2F5(Htaz) is best described by a non centrosymmetric Ima2 model with refined lattice parameters a = 9.1467(2) Å, b = 9.4641(2) Å and c = 7.4829(2) Å. Magnetic susceptibility and magnetisation measurements reveal that strong antiferromagnetic exchange interactions prevail in Fe2F5(Htaz) leading to a magnetic ordering transition at TN = 93 K. Analysis of low-temperature powder neutron diffraction data indicates that below TN, the Fe2+ sublattice is ferromagnetic, with a moment of 4.1(1) μB per Fe2+ at 2 K, but that an antiferromagnetic component of 0.6(3) μB cants the main ferromagnetic component of Fe3+, which aligns antiferromagnetically to the Fe2+ sublattice. The zero-field and in-field Mössbauer spectra give clear evidence of an excess of high-spin Fe3+ species within the structure and a non collinear magnetic structure.
Original language | English |
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Journal | Philosophical Transactions of the Royal Society. A, Mathematical, Physical and Engineering Sciences |
Volume | 377 |
Issue number | 2149 |
Early online date | 27 May 2019 |
DOIs | |
Publication status | Published - Jul 2019 |
Keywords
- Neutron diffraction
- Fluorides
- 57Fe Mössbauer spectrometry
- Coordination frameworks
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Strong magnetic exchange and frustrated ferrimagnetic order in a weberite-type inorganic-organic hybrid fluoride (dataset)
Clark, L. (Creator), Pimenta, V. (Creator), Lhoste, J. (Creator), da Silva, I. (Creator), Payen, C. (Creator), Grenèche, J.-M. (Creator), Maisonneuve, V. (Creator), Lightfoot, P. (Creator) & Leblanc, M. (Creator), ISIS, 2019
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