Enhanced flux pinning in (Bi,Pb)-2223/Ag tapes by slight Pr-doping

(Bi,Pb)(2.2)Sr2Ca2.2-xPrxCu3Oy silver sheathed tapes with Pr-doping amount of x = 0.0, 0.001 and 0.002 have been prepared by powder-in-tube method. X-ray diffraction analyses manifest that the tapes with x = 0.001 and 0.002 (doped) have less Pb-rich phase than the tape with x = 0.0 (un-doped). Transmission electron microscopy images show that the Pb-rich phase particles of similar to 40 nm are embedded in un-doped (Bi,Pb)-2223 grain matrix, while defects induced by Pr-doping with the size smaller than that of the Pb-rich phase particles exist in the doped samples. As compared with the un-doped tape, the magnetic field dependence of critical current densities of the doped tapes are noticeably improved at 77 K, and their irreversibility lines are also shifted to higher temperatures and magnetic fields and activation energies of flux motion increased drastically. The enhanced flux pinning seems to mainly originate from the fine normal-like defects induced by the partial Pr-substitution for Ca. (C) 2001 Elsevier Science B.V. All rights reserved.