Synthesis, characterization, and electronic structure of a new molybdenum bronze SnMo₄O₆

SnMo₄O₆ was synthesized at low temperature from the mixture of MoO₂ and Mo₂O₃ using Sn flux. The structure of this compound was determined by the single-crystal X-ray diffraction method. It crystallizes in the tetragonal space group P4/mbm with a = 9.580(4) and c = 2.843(6). The structure of SnMo₄O₆ is composed of edge-sharing Mo₆O₁₂ chains extending down the c axis, and four chains are connected to form channels filled with Sn cations. The resistivity measurement for SnMo₄O₆ along the chain direction shows that the compound is metallic down to 50 K, and it exhibits semiconducting behavior as the temperature lowers further. It was found from extended Huckel tight-binding band calculation that the compound is likely to be a quasi-one-dimensional metal. The metal-insulator transition in this compound is due to the Fermi surface nesting phenomenon, which originates in the one-dimensional characteristic.