Crystal structures and magnetic properties of mixed iridium-ruthenium triple perovskites. 2. Ba3MRuIrO9 (M=Li, Na, Mg, Ni, Zn, Bi, In).

Crystal structures and magnetic properties of polycrystalline Ba3MRuIrO9 (M1+=Li, Na; M2+=Mg, Ni, Zn; M3+=Bi, In) were investigated. Rietveld refinements of the crystal structures using powder diffraction data indicate that, with the exception of Ba3BiRuIrO9, all compounds crystallize in the 6H-BaTiO3 structure type in space group P63/mmc; Ba3BiRuIrO9 crystallizes in space group C2/c. The 6H-BaTiO3, or triple-perovskite, structure is composed of hexagonal and cubic stacking of [AO3] layers and contains face- and corner-sharing octahedra. The structures in this study contain a disordered mixture of Ir and Ru in the face-sharing octahedra dimers, which are connected via corner-shared MO6 octahedra. Magnetic susceptibility measurements as a function of temperature 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 face-sharing octahedra that contain a disordered mixture of Ru and Ir on a single crystallographic site. Over a broad temperature range, a divergence of the zero-field-cooled and field-cooled data were observed for Ba3MgRuIrO9, Ba3NiRuIrO9, Ba3ZnRuIrO9, and Ba3LiRuIrO9.