Tetragonal SmBa2Cu3O7-x [x = 0.74(4)].

Crystals of the title compound, samarium barium copper oxide, were prepared by a modified top-seeded solution-growth method. The crystals thus prepared showed no superconductivity down to 4.2 K. A careful examination showed that the structure closely resembles that of tetragonal YBCO, and there is no atom mixing at the Ba or other sites, within experimental accuracy. A bond-valence-sum calculation at the Ba site also indicated the absence of Sm. Each site is fully occupied by a single atom, except for the oxy­gen site in the basal plane of the CuO6 octahedron. The occupancy of this oxy­gen site is significantly reduced [0.13 (2)], as is commonly observed in the 123 system. The atomic displacement parameters of the atoms in the CuO2 plane, as well as of the Sm atom, are very small, indicating that two equivalent CuO2 planes tightly sandwich the Sm atom.