Synthesis and characterization of antimony-doped Bi-based superconducting materials

A series of antimony-doped bismuth (2 2 2 3) superconducting materials with nominal composition Bi1.7Pb0.4Sr2xSbxCa2Cu3Oy (x = 0.00, 0.02, 0.04, 0.05, 0.06, 0.08 and 0.15) were synthesized by simple solid-state reaction route. The effect of antimony on superconducting behavior has been investigated by X-ray diffraction (XRD), dc electrical resistivity, ac magnetic susceptibility and energy dispersive X-ray (EDX) analyses. Maximum value of the volume percentage of high-Tc (2 2 2 3) phase was calculated to be 69.44 for the sample having Sb content x = 0.06; the same sample has also shown the highest Tc(0) value of 107 K amongst the samples. All the samples appear to have a multiphase character as shown by ac magnetic susceptibility and XRD data. The lattice parameters and cell volume were found to be affected by the substitution of antimony at the strontium-site. Antimony was found to be effective in the formation of the high-Tc phase at a low doping level of 4–6% in this system.