Weak link problem and intragrain current density in polycrystalline Bi1Ca1Sr1Cu2Ox and Tl2Ca2Ba2Cu3O10

Abstract

Polycrystalline sintered specimen were investigated by means of ac susceptibility and inductive critical current measurements. Main objects are whether the new highT c oxides have a weakly coupled intergranular structure and to get information about the intragrain critical current density. The Tl2Ca2Ba2Cu3O10 specimen shows a connective nature similar to YBa2Cu3O7 with low intergrain currents (100 A/cm2 at 100K,B=0 T) and high intragrain ones (4.5·105 A/cm2 at 100K,B=0 T). The investigation of the Bi1Ca1Sr1Cu2Ox specimen becomes complex due to the presence of two superconducting phases and the low intragrain critical current density of the lowerT c phase.