High critical current densities in Bi(2223)/Ag tapes

Abstract

Bi(2223)/Ag monofilamentary tapes have been characterized by measurements of j, vs. B and vs. 8, the angle between the applied magnetic field and the c axis. High degree of texturing, high density and Bi(2223) single phase conditions were found to be the major effects leading to high jc values. A further condition for reaching the highest jc values is a very low overall carbon content, the presence of carbon at the grain boundaries acting as a strong limiting factor. The highest value of jc in the present work is 4.104 A/cm2 at 77K,OT, corresponding to more than 2.105 A/cm2 at 4.2K,OT.

On the thermodynamic critical field in MgB2 superconductor

“…The peaks in the pinning force curves, F p(max) , occur between 2 and 6 kOe, which is substantially lower than the corresponding value for YBa 2 Cu 3 O 7 (at 77 K) or NbTi and Nb 3 Sn superconductors [19][20][21][22].…”

“…This is much lower than what is commonly seen in YBa 2 Cu 3 O 7 , or other classical superconduc- tors, where the peaks occurs at H ∼ 0.4H irr [19][20][21]23]. It is expected from Dew-Hughes model that the normalized peak occurs at about H = 0.5 H irr , and its position increases with increasing the density of defects [22,23].…”

Recrystallization of high temperature superconductors

“…Typically large segregated particles of Sr -Ca -Cu -0, Ca -Cu -0, and Cu -0 phases coexist with the 2223 during the process. Carbonates also might be present and it was found [38] that they suppress J, because they possibly result in poor grain connectivity and high porosity. Y. Ikeda et a1 [39] give a comprehensive overview of various phases formed when mixtures of Bi203, SrC03, CaC03, and C u 0 are heated in air.…”

Progress in development of tapes and magnets made from Bi-2223 superconductors

“…Powder-in-tube (PIT) processing has been used by several research groups to obtain very high critical current density (Jc) in short lengths of Ag- [1][2][3][4][5][6][7][8][9] Because the Jc values of BSCCO tapes at 4.2 K and in high magnetic fields are significantly higher than those of low-Tc superconductors such as NbTi and Nb3Sn, BSCCO can be used to replace presently used low-Tc superconductors. Additionally, BSCCO conductors can be used well beyond the temperature and field capability of low-Tc superconductors.…”

“…On the other hand, tapes fabricated by the PIT process seem to exhibit very high Jcs. 1,[8][9][10][11][12] The silver sheath used in the PIT process provides good thermal, mechanical, and electrical stability. Additionally, because the PIT process is analogous to the current manufacturing technology for fabricating low-Tc superconductors, it can be very easily modified to fabricate high-Tc superconductors at the industrial level.…”