Valency pair and properties of 1:1 ordered perovskite-type compounds Sr(2)MMoO(6) (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 Sr(2)MMoO(6)(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+(3d(5):t(2g)(3)e(g)(2)), Mo6+(4d(0))}, {Fe3+(3d(5+):t(2g)(3)e(g)(2)), Mo5+(4d(1):t(2g)(1))} and (Co2+(3d(7):t(2g)(5)e(g)(2)), Mo6+(4d(0))}. The properties of these compounds are summarized as follows: Sr2MnMoO6, semiconductive and antiferromagnetic; Sr2FeMoO6,metallic and ferrimagnetic; Sr2CoMoO6, semiconductive and antiferromagnetic.