Superconductivity in sulfur-containing R-Ba-Cu-O compounds

We have prepared samples of RBa2Cu3OγSy (R=Y,Er,Nd) and studied them by x-ray powder diffraction, dc resistivity, and thermoelectric power measurements. All the compounds present a large proportion of secondary phases which are dominated by BaSO4, as confirmed by the x-ray-diffraction patterns. Samples with R=Y or Er are still high-temperature superconductors confirming the fact that the sulfur atoms are not inserted, or with a very low …