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- Becker, Richard, et al.
(författare)
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Crystal structure and magnetic properties of the new cobalt tellurite halide Co5(TeO3)4X2 (X = Cl, Br)
- 2007
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Ingår i: Solid State Sciences. - : Elsevier BV. - 1293-2558 .- 1873-3085. ; 9:3-4, s. 223-230
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Tidskriftsartikel (refereegranskat)abstract
- Two new cobalt tellurite halides Co5(TeO3)4Cl2 and Co5(TeO3)4Br2 have been synthesized and found to be iso-structural with Ni5(TeO3)4X2 (X = Cl, Br). Co5(TeO3)4X2 crystallizes in the monoclinic system space group C2/c, and the Br-phase has the lattice parameters a = 20.440(1) Å, b = 5.2760(2) Å, c = 16.4710(7) Å, β = 124.790(5)°, and Z = 4. The crystal structures were solved from single-crystal X-ray data, R1 = 1.90 and 1.77, respectively, for the Cl- and Br-phases. The crystal structure is layered with only weak van der Waals' interactions in between the layers. The layers are built by large [Co5O16X2] groups consisting of five edge- and face-sharing Co-octahedra. Each group is connected to adjacent groups via corner sharing through common oxygen atoms as well as through [TeO3E] groups. Magnetic susceptibility measurements on oriented single crystals reveal pronounced anisotropy in a broad temperature range and clear signs of antiferromagnetic ordering at low temperatures. Anisotropic susceptibility of an iso-structural Ni-based compound was also studied and compared with the corresponding results of Co5(TeO3)4X2. Magnetic anisotropy is discussed in framework of single-ion anisotropy effects.
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- Becker, Richard, et al.
(författare)
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Crystal structure and magnetic properties of two new cobalt selenite halides : Co5(SeO3)4X2 (X=Cl, Br)
- 2007
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 180:3, s. 1051-1059
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Tidskriftsartikel (refereegranskat)abstract
- Two new isostructural cobalt selenite halides Co5(SeO3)4Cl2 and Co5(SeO3)4Br2 have been synthesized. They crystallize in the triclinic system space group P−1 with the following lattice parameters for Co5(SeO3)4Cl2: a=6.4935(8) Å, b=7.7288(8) Å, c=7.7443(10) Å, α=66.051(11)°, β=73.610(11)°, γ=81.268(9)°, and Z=1. The crystal structures were solved from single-crystal X-ray data, R1=3.73 and 4.03 for Co5(SeO3)4Cl2 and Co5(SeO3)4Br2, respectively. The new compounds are isostructural to Ni5(SeO3)4Br2. Magnetic susceptibility measurements on oriented single-crystalline samples show anisotropic response in a broad temperature range. The anisotropic susceptibility is quantitatively interpreted within the zero-field splitting schemes for Co2+ and Ni2+ ions. Sharp low-temperature susceptibility features, at TN=18 and 20 K for Co5(SeO3)4Cl2 and Co5(SeO3)4Br2, respectively, are ascribed to antiferromagnetic ordering in a minority magnetic subsystem. In isostructural Ni5(SeO3)4Br2 magnetically ordered subsystem represents a majority fraction (TN=46 K). Nevertheless, anisotropic susceptibility of Ni5(SeO3)4Br2 is dominated at low temperatures by a minority fraction, subject to single-ion anisotropy effects and increasing population of Sz=0 (singlet) ground state of octahedrally coordinated Ni2+.
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- Becker, Richard, et al.
(författare)
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Crystal Structure of the New Cobalt Tellurite Chloride Co5Te4O11Cl4
- 2007
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Ingår i: Zeitschrift für Anorganische und Allgemeines Chemie. - Weinheim : WILEY-VCH Verlag. - 0044-2313 .- 1521-3749. ; 633:3, s. 422-424
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Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of the new compound Co5Te4O11Cl4 is described. It crystallizes in the triclinic system, space group P-1 with the unit cell parameters a = 822.26(8) pm, b = 1029.7(1) pm, c = 1031.1(1) pm, = 110.80(1)°, β = 97.950(9)°, = 98.260(9)° and Z = 2. The structure is layered along the bc–plane and built by [CoO5Cl], [CoO4Cl2] and [CoO4Cl] polyhedra sandwiched by [TeO3E] and [TeO4E] polyhedra. The layers can be regarded as infinite molecules without any net charge and only weak van der Waals forces connect them to each other. The halides and the lone-pair, E, of TeIV protrude from the layers.
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- Zhang, Dong, et al.
(författare)
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Crystal Structure and Magnetic Properties of Two New Antiferromagnetic Spin Dimer Compounds; FeTe3O7X (X = Cl, Br)
- 2011
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 50:24, s. 12877-12885
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Tidskriftsartikel (refereegranskat)abstract
- Two new isostructural layered oxohalides FeTe(3)O(7)X (X = Cl, Br) were synthesized by chemical vapor transport reactions, and their crystal structures and magnetic properties were characterized by single-crystal X-ray diffraction, Raman spectroscopy, magnetic susceptibility and magnetization measurements, and also by density functional theory (DFT) calculations of the electronic structure and the spin exchange parameters. FeTe(3)O(7)X crystallizes in the monoclinic space group P2(1)/c with the unit cell parameters a = 10.7938(5), b = 7.3586(4), c = 10.8714(6) angstrom, beta = 111.041(5)degrees, Z = 4 for FeTe(3)O(7)CI, and a = 11.0339(10), b = 7.3643(10), c = 10.8892(10) angstrom, beta = 109.598(10)degrees, Z = 4 for FeTe(3)O(7)Br. Each compound has one unique Fe(3+) ion coordinating a distorted [FeO(5)] trigonal bipyramid. Two such groups share edges to form [Fe(2)O(8)] dimers that are isolated from each other by Te(4+) ions. The high-temperature magnetic properties of the compounds as well as spectroscopic investigations are consistent with an isolated antiferromagnetic spin dimer model with almost similar spin gaps of similar to 35 K for X = Cl and Br, respectively. However, deviations at low temperatures in the magnetic susceptibility and the magnetization data indicate that the dimers couple via an interdimer coupling. This interpretation is also supported by DFT calculations which indicate an interdimer exchange which amounts to 25% and 10% of the intradimer exchange for X = Cl and Br, respectively. The magnetic properties support the counterion character and a weak integration of halide ions into the covalent network similar to that in many other oxohalides.
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- Zhang, Dong, et al.
(författare)
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Separation of the oxide and halide part inthe oxohalide Fe3Te3O10Cl due to high Lewis acidity of the cations
- 2009
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 48, s. 6599-6603
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Tidskriftsartikel (refereegranskat)abstract
- crystallizes in the monoclinic space group P21/c. The crystal structure comprises channels where the Cl ions and also the stereochemically active lone-pair electrons on Te4+ are located. The Cl-atoms rather act as counter ions than being part of the covalent/ionic network. The magnetic susceptibility indicates antiferromagnetic ordering below TN~100 K with a marked splitting of the field cooled (fc) and the zero-field cooled (zfc) susceptibility at low magnetic fields; the splitting disappears at higher magnetic fields. Heat capacity measurements confirm the long range ordering at below this temperature. Only moderate shifts are observed with Raman spectroscopy at the magnetic transition
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