Thermal, spectroscopic and magnetic properties of the Co {sub x}Ni{sub 1-x}(SeO{sub 3}).2H{sub 2}O (x = 0, 0.4, 1) phases
- Departamento de Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Apdo. 644, E-48080 Bilbao (Spain)
- Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Apdo. 644, E-48080 Bilbao (Spain)
The Co {sub x}Ni{sub 1-x}(SeO{sub 3}).2H{sub 2}O (x = 0, 0.4, 1) family of compounds has been hydrothermally synthesized under autogeneous pressure and characterized by elemental analysis, infrared and UV-vis spectroscopies and thermogravimetric and thermodiffractometric techniques. The crystal structure of Co{sub 0.4}Ni{sub 0.6}(SeO{sub 3}).2H{sub 2}O has been solved from single-crystal X-ray diffraction data. This phase is isostructural with the M(SeO{sub 3}).2H{sub 2}O (M = Co and Ni) minerals and crystallizes in the P2{sub 1}/n space group, with a 6.4681(7), b = 8.7816(7), c = 7.5668(7) A, {beta} = 98.927(9) deg and Z = 4. The crystal structure of this series of compounds consists of a three-dimensional framework formed by (SeO{sub 3}){sup 2-} selenite oxoanions and edge-sharing M{sub 2}O{sub 10} dimeric octahedra in which the metallic cations are coordinated by the oxygens belonging to both the selenite groups and water molecules. The diffuse reflectance spectra show the essential characteristics of Co(II) and Ni(II) cations in slightly distorted octahedral environments. The calculated values of the Dq and Racah (B and C) parameters are those habitually found for the 3d{sup 7} and 3d{sup 8} cations in octahedral coordination. The magnetic measurements indicate the existence of antiferromagnetic interactions in all the compounds. The magnetic exchange pathways involve the metal orbitals from edge-sharing dimeric octahedra and the (SeO{sub 3}){sup 2-} anions which are linked to the M{sub 2}O{sub 10} polyhedra in three dimensions.
- OSTI ID:
- 20889769
- Journal Information:
- Materials Research Bulletin, Vol. 40, Issue 5; Other Information: DOI: 10.1016/j.materresbull.2005.02.005; PII: S0025-5408(05)00044-9; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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