Synthesis and magnetic properties of 12L-perovskites Ba4LnIr3O12 (Ln = lanthanides)

New quadruple perovskite oxides Ba4LnIr3O12 (Ln = lanthanides) were prepared and their magnetic properties were investigated. They crystallize in the monoclinic 12L-perovskite-type structure with space group C2/m. The Ir3O12 trimers and LnO6 octahedra are alternately linked by corner-sharing and form the perovskite-type structure with 12 layers. The Ln and Ir ions are both in the tetravalent state for Ln = Ce, Pr, and Tb compounds (Ba4Ln^[4+]Ir^[4+]3O12), and for other compounds (Ln = La, Nd, Sm-Gd, Dy-Lu), Ln ions are in the trivalent state and the mean oxidation state of Ir ions is +4.33(Ba4Ln^[3+]Ir^[4.33+]3O12). An antiferromagnetic transition has been observed for Ln = Ce, Pr, and Tb compounds at 10.5, 35, and 16 K, respectively, while the other compounds are paramagnetic down to 1.8 K.