Crystal Structures and Magnetic Properties of Mixed Iridium−Ruthenium Triple Perovskites. 1. Ba₃MRuIrO₉ (M = Lanthanide, Y)

Crystal structures and magnetic properties of Ba₃MRuIrO₉ (M = lanthanides, Y) were investigated. Rietveld refinements using powder diffraction data indicate that all the compounds crystallize in the 6H-BaTiO₃ structure type in space group P6₃/mmc. Magnetic susceptibility measurements were carried out on each compound. Effective magnetic moments were smaller than values estimated using spin-only moments, which indicate the presence of spin−orbit coupling and strong interactions in the [(Ru_0.5Ir_0.5)₂O₉] face-sharing octahedra that contain a disordered mixture of Ru and Ir on a single crystallographic site. Magnetic anomalies were observed for the compounds Ba₃PrRuIrO₉, Ba₃TbRuIrO₉, and Ba₃NdRuIrO₉ at 3.5, 13, and 8 K, respectively.