Magnetic and calorimetric studies on Ba(3)LnRu(2)O(9) (Ln = Gd, Ho-Yb) with 6H-perovskite structure

Crystal structures and magnetic properties of the quaternary oxides Ba(3)LnRu(2)O(9) (Ln=Gd, Ho-Yb) are reported. These compounds have the 6H-perovskite structure with space group P6(3)/mmc. This structure consists of linkages between LnO(6) octahedra and Ru2O9 dimers made from face-shared RuO6 octahedra. From their magnetic susceptibility and specific heat measurements, we have found that these compounds show magnetic anomalies at 14.8 K (Ln=Gd), 10.2 K (Ho), 6.0 K (Er), 8.3 K (Tm), and 4.5 K (Yb). It is considered that they are due to the antiferromagnetic interaction between Ln(3+) ions.