Improvement in critical current density of Bi2Sr2Ca1Cu2Ox tapes synthesized by doctor-blade casting and melt growth

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Abstract
Bi2Sr2Ca1Cu2Ox superconducting tape with an excellent Jc at 4.2 K has been synthesized by a modified doctor‐blade process. A green tape prepared by doctor‐blade casting is laid on a silver foil and heat treated at various temperatures below and above its partial melting temperature. The Jc of the tape increases dramatically when heat treated in a narrow temperature range just above the melting temperature. A highly oriented layer structure with c‐axis alignment is obtained by the growth of aligned Bi2Sr2Ca1Cu2Ox grains in the partially melted state. This oriented microstructure produces an exceptional increase in Jc . Typical Jc ’s of the tape at 4.2 K are 50 000 A/cm2 at 0 T, 22 000 A/cm2 at 10 T, and 17 000 A/cm2 at 23 T. Note the small magnetic field dependence in Jc above 10 T.