SUPERCONDUCTIVITY AT 124 K IN (TL, PB)SR2CA2CU3O9

We report the preparation of almost phase pure (Tl0.5Pb0.5)Sr2Ca2Cu3O9, which is characterized by high temperature superconductivity with T(c onset) = 130 K, T(c midpoint) = 124 K, T(czero) = 122.5 K as measured by electrical resistance, and a diamagnetic onset temperature, T(cmag) of 124 K determined by DC magnetic susceptibility. The new procedure involves synthesizing a material with nominal stoichiometry (Tl0.5Pb0.5)Sr1.6Ca2.4Cu3O9, which is encapsulated in gold foil and sintered at 950-degrees-C for 3 h in oxygen, then sealed in an evacuated quartz tube and finally annealed at 700 approximately 750-degrees-C for 5 approximately 10 days. From the results of X-ray diffraction and energy-dispersive X-ray spectrometry (EDS), we have identified the phase responsible for the superconductivity in the annealed sample to be Tl0.58(3)Pb0.38(2)Sr1.9(2)Ca2.1(1)Cu3O9. No superlattice and intergrowth along the a* and c* directions were observed but streaks along the c*-axis were found from microcrystallites of the annealed sample.