Lithium Ruthenates: Controlling Dimensionality and Topology of Magnetic-Ion Arrangements

In order to control the dimensionality and the topology of the arrangement of magnetic Ru ions, NaCl-type lithium ruthenates have been investigated. Three types of lithium ruthenates, Li$_{3}$RuO$_{4}$, Li$_{2}$RuO$_{3}$, and cubic-Li$_{x}$RuO$_{1+x}$, were synthesized using a hydrothermal method. All of them have NaCl-type structure, but the arrangements of the cations, Li$^{+}$ and Ru$^{5+}$ (or Ru$^{4+}$), differ from each other. Li$_{3}$RuO$_{4}$ with one-dimensional zigzag chains of Ru ions undergoes an antiferromagnetic transition at 66 K and exhibits an irreversibile magnetism below 32 K, where the zero-field-cooled susceptibility differs from the field-cooled susceptibility. Li$_{2}$RuO$_{3}$ with a two-dimensional honeycomb network of Ru ions demonstrates a paramagnetism almost independent of temperature. A novel ruthenate cubic-Li$_{x}$RuO$_{1+x}$, in which Ru and Li randomly occupy the cation sites of NaCl lattice, undergoes a spin-glass transition at 10 K.