MAGNETIC-FIELD AND TEMPERATURE-DEPENDENCE OF THE TRANSPORT CRITICAL CURRENT-DENSITY AND FLUX PINNING IN ANISOTROPIC (BI,PB)2SR2CA2CU3OX HIGH T(C) SUPERCONDUCTOR

Voltage - current characteristics (V - I) in the temperature range 50 - 80 K and in magnetic fields up to 3 T have been measured on uniaxially pressed bulk (Bi,Pb)2Sr2Ca2Cu3Ox ( = 2223) samples in both parallel and perpendicular orientation of the external magnetic field B(ext) with respect to the direction of pressing. The critical current density J(c), determined from V - I, decreased in magnetic field exponentially with the characteristic field B(s)(T). Large anisotropy of the temperature dependences of B(s) in the two orientations of B(ext) was observed. Bs(T) from presented measurements were compared with B(s)(T) in Bi-based 2212 samples. It was found that B(s)(T) in 2223 samples were significantly shifted towards higher temperatures. As for 2212 material, the reduced flux-pinning force density in 2223 samples scaled with B(s); the shape of the scaling function was different in the two orientations of B(ext). This result indicates that different mechanisms are responsible for flux pinning in various orientations of the external magnetic field. The shape of the voltage-current characteristics will be discussed.