Critical current density significantly enhanced by hot pressing in Bi-2223/Ag multifilamentary tapes

Abstract

Ag-sheathed Bi-2223 multifilamentary tapes were prepared with a hot-pressing technique to study its effect on grain connectivity. The critical current density after hot-pressing was significantly enhanced with the maximum increase reached more than double that before. Hot pressing raised the from to for 81-filament tape. However, the critical current density in an applied magnetic field was not improved by hot-pressing. The in a magnetic field of 1 T decreased from 33% of for the original tape to 21% of for the hot-pressed tapes before and after hot pressing. The fraction of strong links was improved from 64% to 73% for the 81-filament tape as a result of hot pressing. Microstructural analysis showed that hot pressing chiefly improved grain connectivity, increased core density, recovered microcracks and reduced secondary phase impurities.

Effects of misfit stresses on high-TCsuperconductivity in thin-film cuprates

“…Pressure and thermal treatment are capable of enhancing the climbing of dislocations and, therefore, according to our model, increasing J c . In this context, recent experimental data [32] on a significant enhancement of J c achieved by hot pressing in Bi-2223/Ag multifilamentary tapes can be seen as supporting the model suggested in this letter.…”

Strongly enhanced current densities in Sr0.6K0.4Fe2As2 + Sn superconducting tapes

“…7(f)), which can be due to the softness of grains during hot deformation. The bending of grains could prevent the formation of cracks effectively in HP-2S samples, introducing greatly enhanced strong-links 21,22,27 . Clearly, the hot pressing process in this work significantly increases the core density of pnictide tapes without crushing of grains, and thus resulting in enhanced transport properties.…”

“…This densification contributes to well grain connectivity in the whole core area. On the other hand, although the superconducting cross sections of HP tapes are greatly reduced compared with those of rolled tapes, the bending of Sr-122 grains without large crack structure is observed in the hot-pressed cores, thus becoming profitable for strong-links of grains 21,22,27 . This is in contrast to the result of cold-pressed tapes in which some crushed planar grains and large crack structures are easily introduced by strong cold force 15,16 .…”

“…Our recent work already suggested that two-step sintering process of precursors helped to complete reaction and homogenous microstructure of Ag-added Sr-122 tapes whose J c was greatly increased by an order of magnitude 20 . On the other hand, hot pressing process could increase core density and improve grain alignment in Bi-2223 tapes, which in return led to higher zero-field J c (H=0) and in-field J c (H) 21,22 . The J c values of MgB 2 tapes were also strongly improved by hot pressing, due to much denser superconducting cores 23,24 .…”

Subsolidus phase relationships of the BaO–R2O3–CuOz (R=Tm and Yb) systems under carbonate-free conditions at =100Pa, and T=750°C and 810°C

“…Intensive research has led to the powder-in-tube (PIT) process for fabrication of Bi-Pb-Sr-Ca-Cu-O (BSCCO) tapes [2][3][4][5][6]. More recently, second-generation high-T c superconductor (HTS) tapes (also called HTS coated conductors) deposited on flexible coatedconductors have received much attention [7][8][9][10][11].…”