The effect of oxygen partial pressure and cooling rate during processing on the critical current density and grain coupling of Bi-2212/Ag tapes

Abstract

We discuss the reason why high oxygen partial pressure (PO2) heat treatment is effective in increasing the critical current density (Jc) of Bi2Sr2CaCu2Oy (Bi-2212)/Ag tapes prepared by a partial melting and subsequent slow cooling method. The high Jc values obtained by the high PO2 heat treatment is attributed to the strong coupling of grains due to the suppression of the formation of non-superconducting phases at grain boundaries and the decrease of anisotropy due to the high oxygen content of the Bi-2212.

Characterization of Superconducting BSCCO/CaSiO₃ and BSCCO/CaZrO₃ Ag PIT Wires

“…Superconducting Ag-sheathed Bi-2212 wires were prepared by powder-in-tube (PIT) method with commercial powder with the addition of 1 wt.% of nanoparticulated calcium silicate or zirconate. The applied heat treatment was based on the experiments of H. Fujii et al [3], in which oxygen partial pressure is applied along the heat treatment up to a maximum temperature (T MAX ) for very short time and cooled down to about 850 °C very slowly. Particularly in this case, the samples were heat treated under 0.1O 2 /0.9Ar gas flow up to 880 °C and 883 °C and cooled down slowly to 853 °C (Fig.…”