Synthesis, crystal growth and structure, magnetic and electrical properties of Ba4Ru2FeO10 and Ba4Ru2CoO10

Crystals of Ba4Ru2FeO10 and Ba4Ru2CoO10 (Cmca, Z = 4, Ba4Ru2FeO10: a = 5.7899(1) Å, b = 13.2898(3) Å, c = 13.0098(4) Å, V = 1001.06 Å3; Ba4Ru2CoO10: a = 5.7691(2) Å, b = 13.2061(3) Å, c = 12.9755(4) Å, V = 988.57 Å3) were obtained from binary oxides and BaCoO3 at 1300 °C. Both compounds crystallize isostructural to Ba4Ru3O10 with different preference of the 3d metal at the two crystallographic sites of Ru in the parent compound. Ba4Ru2FeO10 exhibits a spin-glass like transition at 25 K, while Ba4Ru2CoO10 does not show any magnetic order down to 2 K. According to electrical resistivity measurements performed on single crystals both compounds are semiconductors. In contrast to the variable-range hopping of the transport mechanism of Co bearing material, the electrical resistivity of Ba4Ru2FeO10 follows an activation law resulting in a band gap of approximately 0.98 eV.

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► We have synthesized new quaternary ruthenates Ba4Ru2FeO10 and Ba4Ru2CoO10.
► Both compounds are isostructural to Ba4Ru3O10, substitution of Ru is different for Fe and Co.
► Semiconducting Ba4Ru2FeO10 exhibits a spin-glass like transition at 25 K.
► Semiconducting Ba4Ru2CoO10 shows no magnetic order down to 2 K.