title: Hydrothermal synthesis in the system Ni(OH)(2)-NiSO(4): nuclear and magnetic structures and magnetic properties of Ni(3)(OH)(2)(SO(4))(2)(H(2)O)(2).
abstract: We present the synthesis, characterization by DT-TGA and IR, single crystal X-ray nuclear structure at 300 K, nuclear and magnetic structure from neutron powder diffraction on a deuterated sample at 1.4 K, and magnetic properties as a function of temperature and magnetic field of Ni(3)(OH)(2)(SO(4))(2)(H(2)O)(2). The structure is formed of chains, parallel to the c-axis, of edge-sharing Ni(1)O(6) octahedra, connected by the corners of Ni(2)O(6) octahedra to form corrugated sheets along the bc-plane. The sheets are connected to one another by the sulfate groups to form the 3D network. The magnetic properties measured by ac and dc magnetization, isothermal magnetization at 2 K, and heat capacity are characterized by a transition from a paramagnet (C = 3.954 emu K/mol and theta = -31 K) to a canted antiferromagnet at T(N) = 29 K with an estimated canting angle of 0.2-0.3 degrees. Deduced from powder neutron diffraction data, the magnetic structure is modeled by alternate pairs of Ni(1) within a chain having their moments pointing along [010] and [010], respectively. The moments of Ni(2) atoms are oppositely oriented with respect to their adjacent pairs. The resulting structure is that of a compensated arrangement of moments within one layer, comprising one ferromagnetic and three antiferromagnetic superexchange pathways between the nickel atoms.
authors.affiliation: Groupe des Matériaux Inorganiques, IPCMS, UMR 7504, 23 Rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France. vilminot@ipcms.u-strasburg.fr
authors.forename: Serge
authors.initials: S
authors.lastname: Vilminot
authors.forename: Mireille
authors.initials: M
authors.lastname: Richard-Plouet
authors.forename: Gilles
authors.initials: G
authors.lastname: André
authors.forename: Dariusz
authors.initials: D
authors.lastname: Swierczynski
authors.forename: Françoise
authors.initials: F
authors.lastname: Bourée-Vigneron
authors.forename: Mohamedally
authors.initials: M
authors.lastname: Kurmoo