Effect of delithiation on the dimer transition of the honeycomb-lattice   ruthenate Li$_{2-x}$RuO$_3$
  The honeycomb-lattice ruthenate Li$_2$RuO$_3$ is made heavily Li-deficient by chemical oxidation by iodine. The delithiation triggers a different phase Li$_{2-x}$RuO$_3$, the "D-phase", with superlattice. For the first time we disclose the magnetic and structural properties of the D-phase in the dimer-solid state. The low temperature magnetic susceptibility and the bond lengths indicate a bonding configuration consisting of both Ru$^{4+}$-Ru$^{4+}$ and Ru$^{5+}$-Ru$^{5+}$ dimers. 
Marco-Polo Jimenez-Segura, Atsutoshi Ikeda, Simon A. J. Kimber,   Carlotta Giacobbe, Shingo Yonezawa, Yoshiteru Maeno
cond-mat.str-el