Enhanced Jc in Bi-2212 Round Wires With Optimization of Calcination Atmosphere

High-performance precursor powders are crucial for the transport current of Bi
₂
Sr
₂
CaCu
₂
O
_x
(Bi-2212) round wires. However, the impact of the powder calcination process on the wire performance is not fully understood. Here, Bi-2212 precursor powders were prepared using ultrasonic spray pyrolysis technique and then calcined under different atmospheres. The influences of calcination atmosphere on the microstructures, melting behavior and critical current density (
J
_c
) of Bi-2212 multi-filamentary wires were systematically discussed by tuning the oxygen partial pressure from 0.001 bar to 1.0 bar. As the oxygen partial pressure was increased, a more uniform melting behavior was observed in the Bi-2212 wires, and the large merging bridges was reduced in the filaments. High
J
_c
of 2715 A/mm
²
at 4.2 K, 12 T were achieved in the sample with 1.0 bar O
₂
. Therefore, controlling calcination atmosphere of precursor powder was significant for achieving superior transport current of Bi-2212 wires.