Vilminot, S., Andre, G., Bouree-Vigneron, F., Richard-Plouet, M. & Kurmoo, M. (2007) Magnetic properties and magnetic structures of CU3(OD)(4)XO4, X = Se or S: Cycloidal versus collinear antiferromagnetic structure. Inorg. Chem. 46 10079–10086.
Added by: Laurent Cournède (2016-03-10 22:02:29) |
Type de référence: Article DOI: 10.1021/ic700900b Numéro d'identification (ISBN etc.): 0020-1669 Clé BibTeX: Vilminot2007 Voir tous les détails bibliographiques |
Catégories: CESES Mots-clés: co, crystal-structure, mn, neutron-diffraction, ni, nuclear Créateurs: Andre, Bouree-Vigneron, Kurmoo, Richard-Plouet, Vilminot Collection: Inorg. Chem. |
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Résumé |
We report a comparative study of the magnetic properties of synthetic Cu-3(OH)(4)(SO4)(x)(SeO4)(1-x) and the magnetic structures of the parent compounds. All compounds are isostructural and belong to the orthorhombic class of parent compounds. They consist of 3-legged ribbons of edge-sharing copper octahedra connected by mu(3)-OH and XO4 (X = S or Se). XO4 acts both as one-atom and three-atom bridges to connect seven Cu atoms (six Cu(2) and one Cu(1)) belonging to three neighboring ribbons. The two end members behave as low-dimensional AF with a long-range antiferromagnetic state below 5 (X = S) and 8 K (X = Se); the former shows evidence of a canting. Analyses of the neutron powder diffraction data for X = S were shown to display an ordered magnetic state (k = 0 0 0) where the moments of Cu(2) within the two outer legs are collinear and parallel within each leg but antiparallel from each other; the orientation of the moments of Cu(2) is the c axis, In contrast, for X = Se k = similar to 1/7 0 0 and the magnetic structure is cycloidal and transforms progressively from being incommensurate (T {>} 3 K) to commensurate (T {<}= 3 K). The moments of Cu(2) of each leg are oriented antiparallel as for X = S, but they rotate about the b axis while propagating along the a axis. In both cases the moments of Cu(1) of the inner leg remain random, The magnetic entropy of 15.2 +/- 1 J/kmol for the end members, estimated from integrating the heat capacity/temperature, is close to that expected (3R In 2) for three Cu2+ (S = 1/2).
Added by: Laurent Cournède |