Phase equilibria and melt processing of Bi2Sr2Ca1Cu2O8+<i>x</i> 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 Jc’s of 7×104 A cm−2 have been obtained at 4.2 K in zero field.