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Ba1–xNaxTi2Sb2O (0.0 ≤ x ≤ 0.33): A Layered Titanium-Based Pnictide Oxide Superconductor
- Doan, Phuong, Gooch, Melissa, Tang, Zhongjia, Lorenz, Bernd, Möller, Angela, Tapp, Joshua, Chu, Paul C. W., Guloy, Arnold M.
- Journal of the American Chemical Society 2012 v.134 no.40 pp. 16520-16523
- X-radiation, heat, iron, sodium, temperature
- A new layered Ti-based pnictide oxide superconductor, Ba₁–ₓNaₓTi₂Sb₂O (0.0 ≤ x ≤ 0.33), is reported. X-ray studies revealed that it crystallizes in the tetragonal CeCr₂Si₂C structure. The undoped parent compound, BaTi₂Sb₂O [P4/mmm; a = 4.1196(1) Å; c = 8.0951(2) Å], exhibits a charge density wave (CDW)/spin density wave (SDW) transition at 54 K. Upon chemical doping with Na, the CDW/SDW transition is systematically suppressed, and superconductivity arises with the critical temperature (Tc) increasing to 5.5 K. Bulk superconductivity was confirmed by resistivity, magnetic, and heat capacity measurements. Like the high-Tc cuprates and the iron pnictides, the superconductivity in BaTi₂Sb₂O arises from an ordered state. Similarities and differences between BaTi₂Sb₂O and the cuprate and iron pnictide superconductors are discussed.