Phase equilibria and melt processing of Bi₂Sr₂Ca ₁Cu₂O_8+x tapes at reduced oxygen partial pressures

Abstract

A coulometric titration technique has been employed to melt process Ag-clad Bi2Sr2Ca1Cu2O8+x (Bi-2212) tapes in a region of the phase diagram corresponding to binary melting. This region occurs over the temperature range 798-883°C and the oxygen partial pressure range 2.8×10-4-7.1×10 -2 atm. Phase-pure, well-aligned tapes with magnetization J c's of 7×104 A cm-2 have been obtained at 4.2 K in zero field. © 1994 American Institute of Physics.