Transport critical current density of Ag-sheathed Bi-Sr-Ca-Cu-O multifilament superconductor tapes with magnetic nanopowders γ-Fe 2O3

Abstract

The transport critical current density of multifilament Ag/Bi-Sr-Ca-Cu-O tapes with the addition of magnetic nanopowder (γ-Fe2O 3) has been measured. The tapes were prepared using the powder in tube method with 30 filaments. Three types of Bi-Sr-Ca-Cu-O starting materials namely from solid state reaction without γ-Fe2O3, solid state reaction with γ-Fe2O3 addition and ultrafine powders prepared by coprecipitation method with γ-Fe 2O3 have been used. The starting composition of the γ-Fe2O3 added samples is Bi1.6Pb 0.4Sr2Ca2Cu3O10-(γ- Fe2O3)0.01. The first intermediate rolling enhances Jc but subsequent rolling shows no improvement in J c. Tapes prepared from coprecipitation powders with γ-Fe 2O3 added showed the highest Jc of 7890 A/cm2 at 77 K and in self-field after the first intermediate rolling. These results suggest that intermediate rolling and magnetic nanopowders can be used to improve the critical current density of multifilament Ag/Bi-Sr-Ca-Cu-O superconductor tapes. © 2006 IOP Publishing Ltd.