Journal of Low Temperature Physics, Vol. 117. Nos. 5/6, 1999
*National Research Institute for Metals, Tsukuba 305-0047, Japan
"CREST, Japan Science and Technology Corporation, Tsukuba 305-0047, Japan
***Showa Electric Wire & Cable Co. Ltd., Kawasak 210-0843i, Japan
The high transport critical current density (J
c
) > 500 kA/cm
2
at 4.2 K, 10 T
is obtained in the Bi-2212/Ag multilayer tapes fabricated by using PAIR
(Pre-Annealing and Intermediate Rolling) and melt-solidification process.
This J
c
value is twice higher than existing high-quality Bi-2212/Ag tapes
(250 kA/cm
2
). By applying PAIR process to Bi-2212/Ag tapes, Bi-2212
grain alignment is much improved and a large J
c
enhancement is achieved.
J
c
has been increased strongly by performing pre-annealing at 840°C in
oxygen (1 atm) and intermediate rolling with 25% deformation.
PACS numbers: 74.72.Hs, 85.25.Kx
Bi-Sr-Ca-Cu-O superconductors are expected for practical applications.
Bi2Sr2Ca
2
O
x
(Bi-2212)/Ag tape is one of the promising materials for
magnet applications at low temperatures due to its high critical current
density (J
c
) in high magnetic fields and simple fabricating process. One of
the most effective techniques is the melt-solidification method, obtaining
highly oriented Bi-2212 grains with oxide J
c
(critical current (I
c
)/cross
section of the oxide part) values of order of 100 kA/cm
2
at 4.2 K in high
magnetic fields above 20 T
1-3
In Bi-2212/Ag multifilamentary tapes
fabricated by using powder-in-tube method and melt-solidification process,
Improvement of J
c
and Grain Alignment of Bi-2212/Ag
Multilayer Tapes by Pre-Annealing and Intermediate
Rolling Process
Hitoshi Kitaguchi*, Hanping Miao*
,
**, Hiroaki Kumakura*, Kazumasa
Togano
*,**
, Takayo Hasegawa*** and Tsutomu Koizumi***
1525
0022-2291/99/J200-1525S16.00/0 © 1999 Plenum Publishing Corporation
1. INTRODUCTION