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Synthesis, Crystal and Magnetic Structure of the Double Perovskites A 2 NiMoO 6 (A = Sr, Ba): A Neutron Diffraction Study
Author(s) -
MartínezLope María J.,
Alonso José A.,
Casais María T.
Publication year - 2003
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200300063
Subject(s) - neutron diffraction , chemistry , tetragonal crystal system , crystallography , crystal structure , crystallite , divalent , antiferromagnetism , x ray crystallography , magnetic structure , diffraction , mineralogy , magnetization , condensed matter physics , magnetic field , physics , organic chemistry , quantum mechanics , optics
A 2 NiMoO 6 (A = Sr, Ba) perovskites have been prepared in polycrystalline form by thermal treatment, in air, of previously decomposed citrate precursors. These materials have been studied by X‐ray (XRD) and neutron powder diffraction (NPD) data. At room temperature, the crystal structure is tetragonal, space group I 4/ m , for Sr 2 NiMoO 6 and for Ba 2 NiMoO 6 the crystal structure is cubic, space group Fm $\bar 3$ m . Both perovskites contain divalent Ni cations. The low temperature antiferromagnetic ordering has been followed from sequential neutron diffraction data. Peaks of magnetic origin appear in the NPD patterns below temperatures of T N = 81.2 K and T N = 64.3 K for the Sr and Ba compounds, respectively. The magnetic structures are defined by a propagation vector k = (1/2,0,1/2) for Sr 2 NiMoO 6 and k = (1/2,1/2,1/2) for Ba 2 NiMoO 6 . The refined magnitude of the Ni magnetic moments also suggests a divalent oxidation state with S = 1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)