Enhanced flux pinning in Ag-sheathed (Bi, Pb)₂Sr₂Ca₂Cu₃O_{10+ delta}tapes by post-annealing

Abstract

A significant enhancement of J , in a magnetic fieid for Ag-sheathed Bi-Pb-Sr-Ca-Cu-0 (BPSCCO) tapes has been achieved by post-annealing at reduced temperature after processing. This post-annealing at reduced temperature introduced extra oxygen into the oxide superconductor. Weak links were eliminated and J, has been increased in the post-annealed tapes by a factor of 1.5 to 3 at 0 T over the normally processed tapes without post-annealing. The optimized J , values for the post-annealed tapes ranged from 30000 to 57 000 A cm-2 at 77.3 K and 0 T. The irreversibility lines measured by a DC SQUID exhibited an improvement in flux pinning in the post-annealed tapes compared with that in normally processed tapes. The introduced oxygen ions are responsible for the enhanced J. and may affect two dimensionality in superconductivity for the BPSCCO system.

Microstructural and superconducting properties of Yb-substituted (Bi,Pb)-2212 superconductor sintered at different temperatures

“…The 2D pancake vortices are mainly confined in the Cu-O 2 layers [12]. Also Pb doping in the system improves the coupling between the Cu-O 2 layers by reducing the anisotropy and increasing the c-axis conductivity [2]. Substitution of each Yb atom at the Sr site of (Bi,Pb)-2212 supplies an additional electron to the system and reduces hole density.…”

“…Therefore, there are two ways to enhance the flux pinning ability and hence the transport properties of (Bi,Pb)-2212 superconductor at high temperatures and high magnetic fields. One method is to reduce the anisotropy of the material [2], which strengthens the interlayer coupling between Cu-O 2 layers and increases the flux pinning potential. The other method is to introduce artificial defects, with the size matching the coherence length, as extra pinning centers.…”

Processing and fabrication of high-Tc superconductors for electric power applications

“…Nomura et al [26] concluded that Jc values of Bi-2223 tapes increase with an increase in oxygen content. In previous work with the University of Pittsburgh [27], we also showed that cooling rate had a pronounced effect on transport J,.…”

The Impact of Fe Doping on Jc Behavior of Bi2223/Ag Tapes under Magnetic Field

“…However, Bi2223/Ag tape exhibits a poor J c behavior under magnetic fields, which impedes the commercialization of this material. J c decreases drastically with the increase of magnetic fields as a result of the motion of the magnetic flux lines, which arises from the weak flux pinning of the Bi-system materials [2]. Introducing artificial defects as extra pinning centers by means of physical and chemical doping is an effective method to improve the flux pinning ability of this material [3][4][5].…”