Synthesis, Crystal and Magnetic Structure of the New Double Perovskite Ba2MnMoO6

Abstract

We describe the preparation and characterization of a new double perovskite of formula Ba2MnMoO6. It has been obtained in polycrystalline form by thermal treatment, in a H2/N2 flow, of previously decomposed citrate precursors. This material has been studied by X-ray (XRD) and neutron powder diffraction (NPD): it crystallizes, at room temperature, in the cubic space group Fm3̄̄̄̄̄m, and shows an almost perfect ordering between Mn2+ and Mo6+ cations at the B substructure. Below TN = 10.8 K, it experiences a long range antiferromagnetic ordering that was followed from sequential NPD data. The low-temperature magnetic structure is defined by the propagation vector k = (1⁄2, 1⁄2, 1⁄2). The ordered magnetic moment of Mn is found to be 4.04(8) μB at 2 K, suggesting a divalent oxidation state for Mn cations, in a high spin t3 2ge2 g (S = 5/2) electronic configuration.