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Jc enhancement in Bi-2223/Ag tapes by low temperature pre-annealing
$Bu#(JC.H. Jiang, H. Kumakura, T. Koizumi
National Institute for Materials Science
The green Bi-2223/Ag tapes were firstly pre-annealed at different temperatures in air or in pure argon for 10 h, and then were pressed and heat treated under the same thermo-mechanical procedure. In comparison with the not pre-annealed samples, the Jc of the tapes pre-annealed in pure Ar were seriously degraded no matter which annealing temperature was used. However, a 25% enhancement in Jc (from 17.3 kA/cm2 to 21.7 kA/cm2 in average) was obtained in the samples pre-annealed in air at 800$B!k(JC. The development of Bi-2212 texture during the pre-annealing and a better phase formation and grain growth during the subsequent heat treatments might account for the Jc improvement, which could be confirmed by their better grain connectivity and flux pinning ability characterized by the magnetic hysteresis measurements.
Powder-in-tube method,Bi-2223,pre-annealing,critical current density,,