Synthesis and formation of TlSr1212 superconductors from coprecipitated oxalate precursors

TlSr1212 superconductors were synthesized by solid-state reaction using Tl-containing precursor powder prepared by coprecipitation of metal acetates with stoichiometric ratio based on Tl0.8Bi0.2Sr2Ca0.8Y0.2Cu2O7±δ composition. The samples were sintered at temperatures between 870 and 980 °C for different durations. XRD patterns for samples sintered at 870 °C showed formation of dominant 1212 phase in addition to minor 1201 phase and SrCO3 impurity. At this sintering temperature, the best superconducting behavior with Tc zero of 94 K was observed for the sample sintered for 60 min. SEM investigations on the sample revealed elongated grains with a slight directional grain alignment. Effect of using metal acetates with a slightly different starting stoichiometric ratio of Tl0.96Bi0.2Sr1.6Ca0.8Y0.2Cu2O7±δ was also investigated.