Study of critical current density in (Tl0.5Pb0.5)Ca2Sr2Cu3Oy

(Tl0.5Pb0.5)Ca2Sr2Cu3Oy compound with Tco = 113 K has been achieved. The intragranular critical current density Jc at Ha = 1 T is estimated to be about 6 × 106 A/cm2 at 5 K and has a logarithmic temperature dependence below 40 K. An anomalous dimpling behavior occurs near the origin of the loop for powder sample. This Jc decreases slightly with magnetic field at low temperature and reaches a stable value at high field. The flux pinning centers may be considered as coming from the grain boundaries by the observation of the strong shielding effect and large hysteresis curves in bulk specimen compared with those in powder specimen.