Superconductivity in single crystals of the nonperovskite-like cuprate Ba2Cu3O6−x

Spontaneous crystallization from a solution in a melt at a pressure of (0.8–1)×10−3 Pa was used to obtain single crystals of a new nonperovskite-like superconducting phase Ba2Cu3O6−x space group Pccm, a=13.065, b=20.654, and c=11.431 Å). The superconducting properties of the crystals were investigated by modulated microwave absorption. The superconducting transition temperatures were 5 K (sample No. 1), 7 K and 13 K (sample No. 2). The superconductivity in the Ba2Cu3O6−x crystals is attributed to the presence of CuO2 chains of edge-sharing copper-oxygen squares. Nonperovskite-like Ba2Cu3O6−x crystals are a new class of one-dimensional (1D) superconductors.