Critical current density at low temperatures in Bi-2212 superconductor with small anisotropy

The critical current density was measured at low temperatures for Bi-2212 single crystals with small anisotropy prepared by oxygen doping and by addition of Pb. The anisotropy parameters of these specimens were about 66. The Pb-doped specimen showed the peak effect up to T/Tc = 0.7. The critical current density at high fields of these specimens was significantly improved as well as the irreversibility field than specimens with larger anisotropy.