Synthesis and Characterization of Cs1–xTi2Te2O (x ≈ 0.2): Electron Doping by Te Resulting in a Layered Metal

Reacting Cs2O1.3, TiTe, TiO2, and Te under inert conditions gives powders of Cs1–xTi2Te2O (x ≈ 0.2). Small single crystals of the same phase were obtained from a CsCl salt melt in closed ampoules. This cesium dititanium ditelluride oxide (P4/mmm, a = 4.0934(3) Å, c = 8.9504(9) Å) is isostructural to CeCr2Si2C and contains layers of face-sharing trans-TiTe4O2 octahedra that are separated by Cs. As Ti occupies only one crystallographic site, its average oxidation state is +2.6, for the Cs deficit x = 0.2. The formally intermediate Ti valence state agrees well with the metallic conductivity and temperature-independent paramagnetic behavior. No superconductivity is observed down to 0.1 K in Cs0.8Ti2Te2O, but the fact that this structure type can accommodate Te2– suggests that electron doping of structurally closely related pnictide oxide superconductors, for example, BaTi2Bi2O, might be possible.