Valency pair and properties of 1:1 ordered perovskite-type compounds Sr2MMoO6 (M = Mn,Fe,Co)

In order to investigate the role of superexchange interaction among 3d and 4d orbitals of transition metal ions via oxygen ions. 1:1 ordered perovskite-type compounds Sr2MMoO6 (M = Mn.Fe.Co) were prepared and their structures and properties were examined. Structural analysis using the powder X-ray diffraction data revealed that all of these compounds have a 1:1 ordered arrangement in their B-sites. Measurements of electrical resistivity and magnetic susceptibility revealed that these compounds have the valency pairs of Mn2+ (3d5:t2g3eg2), Mo6+ (4d0). Fe3+ (3d5:t2g3eg2), Mo5+ (4d1:t2g1) and Co2+ (3d7:t2g5eg2), Mo6+ (4d0). The properties of these compounds are summarized as follows: Sr2MnMoO6, semiconductive and antiferromagnetic: Sr2FeMoO6, metallic and ferrimagnetic: Sr2CoMoO6, semiconductive and antiferromagnetic.