Synthesis and magnetic properties of rare earth ruthenates, <i>Ln</i>₅Ru₂O₁₂ (<i>Ln</i>=Pr, Nd, Sm–Tb)

Single crystals of Ln5Ru2O12 (Ln=Pr, Nd, Sm–Tb) were grown out of either NaOH or KOH fluxes in sealed silver tubes. The crystals of all the phases were observed to be twinned as confirmed by TEM studies. The series crystallize in the C2/m monoclinic system with lattice parameters, a=12.4049(4)–12.7621(6) Å, b=5.8414(2)–5.9488(3) Å, c=7.3489(2)–7.6424(4) Å, β=107.425(3)–107.432(2)° and Z=2. The crystal structure is isotypic with the defect/disorder model of Ln5Re2O12 (Ln = Y, Gd) and consists of one dimensional edge shared RuO6 octahedral chains separated by a two dimensional LnOx polyhedral framework. Magnetic measurements indicate paramagnetic and antiferromagnetic behavior for Ln=Nd, Sm–Gd and Ln=Tb, respectively