TY - JOUR
T1 - Strong magnetic exchange and frustrated ferrimagnetic order in a weberite-type inorganic–organic hybrid fluoride
AU - Clark, Lucy
PY - 2019/7/15
Y1 - 2019/7/15
N2 - 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 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 magnetization 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.
AB - 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 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 magnetization 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.
UR - http://dx.doi.org/10.1098/rsta.2018.0224
U2 - 10.1098/rsta.2018.0224
DO - 10.1098/rsta.2018.0224
M3 - Article
SN - 1364-503X
VL - 377
JO - Royal Society of London. Philosophical Transactions A. Mathematical, Physical and Engineering Sciences
JF - Royal Society of London. Philosophical Transactions A. Mathematical, Physical and Engineering Sciences
IS - 2149
ER -