Structural and magnetic characterisation of the double perovskites AA′MnWO6 (AA′ = Ba2, SrBa, Sr2, SrCa and Ca2)

The double perovskites AA' MnWO6 (AA' = Ba-2, SrBa, Sr-2 , SrCa and Ca-2) have been prepared as pure powders by a conventional solid-state reaction process. Stoichiometric amounts of BaCO3, SrCO3, CaCO3, MnO and WO3 were mixed, ground and calcined in a nitrogen atmosphere. The materials have been studied by X-ray and neutron powder diffraction (NPD), and magnetization measurements. NPD and magnetization measurements have been carried out at different temperatures in order to correlate their structural and magnetic properties. Susceptibility- Temperature (chi-T) curves were measured between 2K and 200K in field cooled (FC) and zero-field-cooled (ZFC) modes with an applied field (H) up to 3T. Rietveld analysis of NPD data shows that the samples were B-site ordered perovskites with different types of lattice distortions. Magnetisation measurements at low temperatures indicate the antiferromagnetic ordering of magnetic moments.