Structure and magnetism of NaRu2O4 and Na2.7Ru4O9

The structures of NaRu2O4 and Na2.7Ru4O9 are refined using neutron diffraction. NaRu2O4 is a stoichiometric compound consisting of double chains of edge sharing RuO6 octahedra. Na2.7Ru4O9 is a non-stoichiometric compound with partial occupancy of the Na sublattice. The structure is a mixture of single, double and triple chains of edge-shared RuO6 octahedra. NaRu2O4 displays temperature independent paramagnetism with χ0=1.23×10-4emu/molRuOe. Na2.7Ru4O9 is paramagnetic, χ0χ0=2.0×10-4emu/molOe with Θw=-11.8K and a Curie constant of 0.0119 emu/mol Oe K. Specific heat measurements reveal a small upturn at low temperatures, similar to the upturn observed in La4Ru6O19. The electronic contribution to the specific heat (γ) for Na2.7Ru4O9 was determined to be15 mJ/moleRu K2.

Magnetic susceptibility versus temperature data for NaRu2O4 (closed squares) and Na2.7Ru4O9 (open triangles). χ0=1.2×10-4emu/molRuOe for NaRu2O4, χ0=2.0×10-4emu/molRuOe for Na2.7Ru4O9. Inset: Inverse magnetic susceptibility vs. temperature data for Na2.7Ru4O9. A linear fit of the high temperature data from 125 to 200 K shows Curie–Weiss behavior, giving Θcw=-11.8K and C=0.0119emu/molOeK.Figure optionsDownload as PowerPoint slide