Synthesis, crystal structure, and magnetic characterization of the double perovskite Ba2MnWO6

The double perovskite Ba2MnWO6 has been prepared as a pure powder by a conventional solid-state reaction process and studied by X-ray, neutron powder diffraction (NPD), magnetization, and AC susceptibility measurements. NPD, magnetization, and AC susceptibility measurements have been carried out at different temperatures to correlate structural and magnetic properties. Rietveld analysis of NPD patterns show that the sample is a B-site ordered perovskite with elpasolite-type structure. At T = 295 K the crystal structure is cubic with a = 8.1985(3) Angstrom, (space group Fm-3m). Temperature-dependent magnetization and AC susceptibility measurements show a transition at similar to 45 K to a weak ferromagnetic state, with a spontaneous moment at 15 K corresponding to mu = 2.2 10(-3) mu (B)/Mn2+. A second transition, to an antiferromagnetic state, still having a weak spontaneous magnetic moment, is detected at similar to9 K. This transition is also confirmed by NPD measurements performed at 4.2 K, showing a number of new distinct magnetic Bragg peaks corresponding to a G-type magnetic structure. (C) 2001 Elsevier Science Ltd. All rights reserved.