Synthesis and Characterization of the Crystal and Magnetic Structures and Properties of the Hydroxyfluorides Fe(OH)F and Co(OH)F

Abstract

The title compounds were synthesized by a hydrothermal route from a 1:1 molar ratio of lithium fluoride and transition-metal acetate in an excess of water. The crystal structures were determined using a combination of powder and/or single-crystal X-ray and neutron powder diffraction (NPD) measurements. The magnetic structure and properties of Co(OH)F were characterized by magnetic susceptibility and low-temperature NPD measurements. M(OH)F (M = Fe and Co) crystallizes with structures related to diaspore-type α-AlOOH, with the Pnma space group, Z = 4, a = 10.471(3) Å, b = 3.2059(10) Å, and c = 4.6977(14) Å and a = 10.2753(3) Å, b = 3.11813(7) Å, and c = 4.68437(14) Å for the iron and cobalt phases, respectively. The structures consist of double chains of edge-sharing M(F,O)6 octahedra running along the b axis. These infinite chains share corners and give rise to channels. The protons are located in the channels and form O-H···F bent hydrogen bonds. The magnetic susceptibility indicates an antiferromagnetic ordering at ∼40 K, and the NPD measurements at 3 K show that the ferromagnetic rutile-type chains with spins parallel to the short b axis are antiferromagnetically coupled to each other, similarly to the magnetic structure of goethite α-FeOOH.

Experimental and computational study of the magnetic properties of ZrMn2−xCoxGe4O12

“…Our data therefore suggest that either the orbital component of the magnetic moment does not order below TC, or that it is quenched in the ferromagnetic phase. Similar behaviour has been seen in Sr2CoGe2O7 and Co(OH)F 37 where it was attributed to chemical disorder and local distortions, neither of which are expected to be present in ZrCo2Ge4O12. The presence of an orbital contribution to the moment in the paramagnetic phase might be considered surprising in the light of the bond lengths listed in Table 4.…”

Quest for Compounds at the Verge of Charge Transfer Instabilities: The Case of Silver(II) Chloride †

“…The layered polymorphs containing the dimeric units are unique among the halides. They are closely related to orthorhombic ramsdellite [36] and monoclinic γ-MnO 2 polymorph form [37]. The ramsdellite structure consists of three-dimensional network of double chains of edge-sharing MnO 6 octahedra while in the γ-MnO 2 the double chains alternate with single chains of MnO 6 octahedra (Figure 2a,b).…”

Strongly canted antiferromagnetic ground state in Cu3(OH)2F4

“…At the same time, in such cases no exchange pathways are present with participation of other transition and non-transition cations which simplifies the analysis of exchange interactions. The basic families of 3d-metals polyanion compounds are the oxyhalides MOX (M = Sc  Cr and Fe; X = Cl and Br) [1][2][3][4][5], the hydroxyhalides M(OH)X (M = Co and Cu; X = F and Cl) [6][7][8] and the trihydroxyhalides M2(OH)3X (M = Mn  Cu; X = Cl and Br) [9][10][11].…”