The h-Sb_x WO_3+2x Oxygen Excess Antimony Tungsten Bronze

We describe the previously unreported oxygen excess hexagonal antimony tungsten bronze is reported, with a composition of Sb_0.5 W₃ O₁₀ , in the following denoted as h-Sb_x WO_3+2x with x=0.167, to demonstrate its analogy to classical A_x WO₃ tungsten bronzes. This compound forms in a relatively narrow temperature range between 580 °Cx WO_3+2x crystallizes in the hexagonal space group P6/mmm with the cell parameters a=7.4369(4) Å and c=3.7800(2) Å. The antimony and excess oxygen occupy the hexagonal channels within the network of corner-sharing WO₆ octahedra. h-Sb_x WO_3+2x has a resistivity of ρ_300 K ≈1.28 mΩ cm at room temperature, with little if any temperature-dependence on cooling. DFT calculations on a simplified model for this compound find a metallic-like electronic structure with the Fermi level falling within rather flat bands, especially around the Γ point.