title: Ionothermal synthesis of open-framework metal phosphates with a Kagomé lattice network exhibiting canted anti-ferromagnetism†Electronic supplementary information (ESI) available: Cif files, atomic parameters, X-ray diffraction patterns, IR spectra, TG curves, and thermal ellipsoid plot and atomic label schemes of compound1-4. See DOI: 10.1039/c4tc00290cClick here for additional data file.
abstract: Four open-framework transition-metal phosphates; (NH4)2Co3(HPO4)2F4(1), (NH4)Co3(HPO4)2(H2PO4)F2(2), KCo3(HPO4)2(H2PO4)F2(3), and KFe3(HPO4)2(H2PO4)F2(4); are prepared by ionothermal synthesis using pyridinium hexafluorophosphate as the ionic liquid. Single-crystal X-ray diffraction analyses reveal that the four compounds contain cobalt/iron-oxygen/fluoride layers with Kagomé topology composed of interlinked face-sharing MO3F3/MO4F2octahedra. PO3OH pseudo-tetrahedral groups augment the [M3O6F4] (1)/[M3O8F2] layers on both sides to give M3(HPO4)2F4(1) and M3(HPO4)2F2(2-4) layers. These layers are stacked along theaaxis in a sequence AA…, resulting in the formation of a layer structure for (NH4)2Co3(HPO4)2F4(1). In NH4Co3(HPO4)2(H2PO4)F2and KM3(HPO4)2(H2PO4)F2, the M3(HPO4)2F2layers are stacked along theaaxis in a sequence AAi… and are connected by [PO3(OH)] tetrahedra, giving rise to a 3-D open framework structure with 10-ring channels along the [001] direction. The negative charges of the inorganic framework are balanced by K+/NH4+ions located within the channels. The magnetic transition metal cations themselves form layers with stair-case Kagomé topology. Magnetic susceptibility and magnetization measurements reveal that all four compounds exhibit a canted anti-ferromagnetic ground state (Tc= 10 or 13 K for Co andTc= 27 K for Fe) with different canting angles. The full orbital moment is observed for both Co2+and Fe2+.
authors.affiliation: Inorganic Chemistry III - Materials Engineering and Characterization , Ruhr-Universität Bochum , D-44780 Bochum , Germany.
authors.forename: Guangmei
authors.initials: G
authors.lastname: Wang
authors.affiliation: Physics of Correlated Matter , Max Plank Institute for Chemical Physics of Solids , D-01187 Dresden , Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Valldor
authors.affiliation: Inorganic Chemistry III - Materials Engineering and Characterization , Ruhr-Universität Bochum , D-44780 Bochum , Germany.
authors.forename: Bert
authors.initials: B
authors.lastname: Mallick
authors.affiliation: Inorganic Chemistry III - Materials Engineering and Characterization , Ruhr-Universität Bochum , D-44780 Bochum , Germany ; Department of Materials Science and Engineering , Iowa State University, and Critital Materials Institute , Ames Laboratory , Ames , IA , USA.
authors.forename: Anja-Verena
authors.initials: AV
authors.lastname: Mudring