Magnetization and flux pinning in the re-cold pressed Bi-based bulk materials

Effect of the re-cold pressing process on structure, magnetization loop and critical current density etc. of Bi1.80 Pb0.34 Sr1.86 Ca2 Cu3 Oy bulk material was experimentally investigated. It is shown that the re-cold pressing process is helpful to increase its volume density and form some orientations of the grains along the direction perpendicular to the pressed surface. On the other hand, flux pinning, which differs from that observed in the conventionally sintered bismuth based bulk sample, is induced into this material by the re-cold pressing process. As a result, these lead to substantively improve on its critical current density and hysteresis loop