Original Network of Zigzag Chains in the β Polymorph of Fe₂WO₆: Crystal Structure and Magnetic Ordering

Abstract

The structural and physical properties of the β polymorph of iron tungstate Fe2WO6 have been investigated by synchrotron and neutron diffraction vs temperature, combined with magnetization and dielectric properties measurements. The monoclinic P21/a crystal structure of β-Fe2WO6 has been determined and consists of an original network of zigzag chains of FeO6 and WO6 octahedra sharing trans and skew edges, connected through corners into a 3D structure. Magnetization measurements indicate an antiferromagnetic transition at T N = 264 K, which corresponds to a ↑↑↓↓ nearly collinear ordering of iron moments inside sequences of four edge-sharing FeO6 octahedra, as determined by neutron diffraction. A canting of the moments out of the ac plane is observed below 150 K, leading to a noncollinear antiferromagnetic structure, the P21/a′ magnetic space group remaining unchanged. These results are discussed in comparison with the crystal and magnetic structures of γ-Fe2WO6 and with the magnetic couplings in other iron tungstates and trirutile Fe2TeO6.

Cationic Ordering, Solid Solution Domain, and Diffuse Reflectance in Fe2WO6 Polymorphs

“…The formation of polymorph β is known to progress very slowly, , and the samples prepared here by spray-drying were no exception with a total residence time at 850 °C of several weeks to obtain a single phase. The room-temperature crystallographic structure of this sample, determined from synchrotron and neutron diffraction, is in complete agreement with the structure that we recently solved for a sample prepared by the SS route . The Rietveld refinement plots and a table of the cell parameters and the crystallographic parameters are provided in the Supporting Information (Figure S3 and Table S1).…”

“…The room-temperature crystallographic structure of this sample, determined from synchrotron and neutron diffraction, is in complete agreement with the structure that we recently solved for a sample prepared by the SS route. 35 The Rietveld refinement plots and a table of the cell parameters and the crystallographic parameters are provided in the Supporting Information (Figure S3 and Table S1).…”

Open-Framework Iron Fluoride Phosphates Based on Chain, Trinuclear, and Tetranuclear Chain FeIII Building Units: Crystal Structures and Magnetic Properties

“…KFe 2 (PO 3 F) 2 F 3 comprises {Fe 2 (O 3 F) 2 F 2 } 10– zigzag chains formed via sharing of trans- corners and cis- corners. β-Fe 2 WO 6 contains zigzag chains of one WO 6 and two FeO 6 octahedra formed via sharing of one trans and one skew edge, while a [FeO 2 O 2/2 F 2/2 ] zigzag chain is solely built up by sharing one skew edge in Na 2 Fe­(PO 4 )­F . In both cases, F – anions are inclined to work as cis -connecting species between the transition-metal cations compared with their O 2– counterparts.…”

Zinc tungstate: a review on its application as heterogeneous photocatalyst

“…Its physical and chemical properties, in terms of molecular and electronic versatility, reactivity, and stability, make ZnWO 4 a promising candidate in photocatalysis for the photodegradation of chemical contaminants [37][38][39][40]. At room temperature, ZnWO 4 has a wolframite-type structure, characterized by a monoclinic symmetry with space group P2/c or C 4 2h and no evidence of polymorphism has been reported in the literature yet for ZnWO 4 as it occurs in SrWO 4 [41], Ag 2 WO 4 [42] and Fe 2 WO 6 [43]. In this structure, Zn and W cations are in octahedral symmetry forming a tridimensional lattice of distorted ZnO 6 and WO 6 octahedra in alternating layers as shown in Fig.…”