Critical current density Jc and V-I characteristics in cold pressing and sauntering BiPbSrCaCuO superconductors

BiPbSrCaCuO bulk materials of nearly pure high-Tc phase were prepared by co-decomposition of metal nitrates and solid reaction method. The prepared bulk materials were further cold pressed and sauntered. X-ray diffraction pattern shows that the grains in the sample are obviously oriented with c-axis perpendicular to the pressing surface. At zero field, the transport Jc of the cold-pressed sample is about 1040 A/cm2, which is greatly improved as compared with that of sauntered one. The V-I characteristics of the sample were investigated and explained based on flux-creeping moedl. It is believed that in the above cold-pressed sample the flux creep constitutes the leading causative factor of the increase of its Jc