Synthesis, structure and magnetic properties of A2MnB′O6 (A=Ca, Sr; B′=Sb, Ta) double perovskites

A2MnB′O6 (A=Ca, Sr; B=Sb, Ta) double perovskites have been synthesized and their structural and magnetic properties have been investigated. Rietveld refinement of the powder X-ray diffraction data for Sr2MnSbO6 indicated significant ordering of Mn and Sb at the B-site while all other phases showed mostly a random distribution of the B-site cations. X-ray absorption spectroscopic data established the presence of Mn in the 3+ and Sb/Ta in the 5+ oxidation states in all the phases. Magnetic susceptibility data indicated ferromagnetic correlations for all the A2MnB′O6 phases with Weiss temperatures varying from 64 to 107 K.