High critical current densities in (Tl0.5Pb0.5)Sr2−xBaxCa2Cu3O9−δ

A high quality of (Tl0.5Pb0.5)Sr1.8Ba0.2Ca2Cu3O9−δ ceramic with Tc≈120 K has been prepared and studied by magnetic measurements. The field and temperature dependence of the intragranular critical current are deduced from the Bean model. For this single (insulating) Tl-O layer material, Jc has a value of the order of 2.105 A/cm2 at 80 K and in a field of 1 T. The mean irreversible line determined from hysteresis loops is also compared to the ones obtained from ac susceptibility measurements.