(Tl, Pb, Bi)Sr2Ca2Cu3Oz superconductors with zero resistance at 120 K

Abstract

We have synthesized new superconductors of nearly single phase with zero-resistance temperatures around 120 K employing a novel method for sintering. The samples included a nominal composition of (Tl 0.64Pb0.2Bi0.16)Sr2Ca 3Cu4Oz. This sample was prepared from the mixture of presynthesized (Tl0.64Pb0.2Bi 0.16)Sr2CaCu2Oz (1212 phase), CaO, and CuO powders. The mixed powder was sintered at 920°C in O2 gas and post-annealed at 400-600°C in O2 gas. The powder x-ray diffraction revealed that the sample was isostructural with the Tl-based (Tl, Pb, Bi)Sr2Ca2Cu3Oz (1223 phase). The sample exhibited a sharp superconducting transition at Tonsetc=125 K and TR=0c=120 K and the superconducting diamagnetic signal at 10 K was about 20% of a full Meissner effect.