The effect of lead content on the critical current density, irreversibility field, and microstructure of Ag-clad Bi_1.8Pb_xSr₂Ca₂Cu₃O_y tapes

Abstract

We studied the effect of lead content (x = 0.20−0.40) on the critical current density Jc (0 T, 77 K), irreversibility field H* (77 K), and microstructure of monocore, Ag-clad Bi1.8PbxSr2Ca2Cu3Oy (2223) tapes, finding that tapes with lower lead contents (x = 0.20–0.25) required higher processing temperatures (840 and 832 °C, respectively) to complete 2223 formation, as compared to the optimum 820 °C reaction temperature of the x = 0.30–0.40 tapes. We found that both the zero-field and the in-field properties correlated strongly to the phase purity with Jc (0 T, 77 K) reaching a maximum of ˜20 kA/cm2 for x = 0.30, and then decreasing with increasing lead content to ˜12 kA/cm2 for x = 0.40. H* (77 K) increased from ˜165 mT at x = 0.20 to ˜265 mT at x = 0.30, then declined to 195 mT at x = 0.40. Optimizing the lead content at x = 0.30 maximized both the connectivity and the flux pinning contributions to the critical current density.

Hole doping in Pb-free and Pb-substituted(Bi,Pb)2Sr2Karppinen1, Lee2, Lee3 et al. 2003Phys. Rev. B20150View full textAdd to dashboardCite

“…4 Also reported is that replacing Bi partially by Pb would enhance the critical-current-density and irreversibility-field characteristics of the Bi-22(nϪ1)n superconductors. [5][6][7] Despite the apparent importance of the ͑Bi,Pb͒-2223 phase, it is one of the least understood ones in terms of hole doping. Also the role of Pb has not been elucidated.…”

Current-limiting mechanisms in individual filaments extracted from superconducting tapes

“…4) in fields above ϳ10 mT. Recent work shows that the pinning properties and the irreversibility field of Bi-2223 can be significantly improved by controlled processing 23,24 , although the origin of the enhanced pinning is not clear. The appearance of c-axis Josephson behaviour shows that better c-axis alignment is also highly desirable, as this will diminish the misorientation of the grains, providing better a-b-plane connectivity.…”

Through-process study of factors controlling the critical current density of Ag-sheathed (Bi,Pb)2Sr2Ca2Cu3Oxtapes

“…It may also be that a component of the increase in H * (77 K) on post annealing is due to changes in Pb and or O content of the 2223 phase with the lower temperature anneal [13]. Precipitation of Pb-rich phases on cooling is well known [13,29,34], as is the influence of Pb content on H * (77 K) [35]. The strong effect of temperature on the composition range of the single-phase field of the 2223 phase has also been presented [36].…”