Preparation of high-performance high temperature superconducting Bi-2212 wires by the spray pyrolysis powder

The Bi2Sr2CaCu2Ox (Bi-2212) precursor powder has been successfully synthesized using the spray pyrolysis method, and the powder has also been made into high critical current density Bi-2212/Ag-alloy wire with 666 filaments through the oxide-powder-in-tube (PIT) and the partial-melt processing (PMP). The advantage of low segregation was found in the spray pyrolysis precursor powder due to the gas-film-barrier high-temperature calcination for the micro-sized atomized solution droplets during the spray pyrolysis process. The droplets are instantly transformed into nearly nano-sized spherical oxide powder, and the liquid phase segregation could only appear inside each of these powder spheres during the process. And the elemental content and elemental distribution in each droplet are perfectly uniform, improving the homogeneity of the final oxide powder. In conventional precursor powders that have only undergone a solid phase sintering, the liquid phase flows between the powders, resulting in severe segregation. As the segregation phenomenon was almost avoided, the content of the Bi2Sr2CuOx (Bi-2201) phase and (Sr, Ca)(x)CuyOz (alkaline earth cuprates, AEC) phase in the precursor powder decreased, leading to the enhancement of the Bi-2212 content in the precursor powder and the conductive characteristics of the wire. The superconducting critical transition temperature T-c of the final wire is 90.53 K, and the & UDelta;T-c value is only 0.08 K. The wire has a small & UDelta;T-c value, further indicating the higher purity of the superconducting sample. The critical current density (J(c)) of the Bi-2212 wire reaches 283 A/mm(2) at 65 K in self-field, which is higher than that of the wire reported in the literature. After high-pressure heat treatment, the highest J(e) and the highest J(c) of the wires reach 538 A/mm(2) and 2987 A/mm(2) at 4.2 K & 12T. It indicated that the spray pyrolysis method would be a candidate method for preparing high-performance Bi-2212 wire.

Automated summary

The Bi2Sr2CaCu2Ox (Bi-2212) precursor powder was successfully synthesized using the spray pyrolysis method, and the powder was made into high critical current density Bi-2212/Ag-alloy wire. The method resulted in low segregation due to high-temperature calcination during the spray pyrolysis process. The spray pyrolysis method shows potential for preparing high-performance Bi-2212 wire.