Synthesis and Characterization of the Pseudo-Hexagonal Hollandites ALi2Ru6O12 (A=Na, K)

The crystal structures, synthesis and physical properties of two ruthenium hollandites ALi2Ru6O12 (A= Na, K) with a new pseduo-hexagonal structure type are described. Like tetragonal hollandites, the framework is made of MO6 octahedra in double chains that then share corner oxygens with each other to create interstitial tunnels that are either hexagonal or triangular in cross section. Magnetic susceptibilities, low temperature specific heat, and electrical resistivities are reported. The data indicates that these materials are normal, low density of states metals. This new structure type can be extended from A= Gp I to A= Gp II ions with the synthesis of CaLi2Ru6O12 and SrLi2Ru6O12.