SOLID-STATE HIGH-OXYGEN-FUGACITY PROCESSING OF BSCCO-2212 SUPERCONDUCTORS

Silver-sheathed powder-in-tube processed tapes and thick films of the Bi2Sr2Ca1Cu2O8+/-delta-type (Bi-2212) superconductor have been anneale d under high temperature, high oxygen fugacity (i.e. fO(2) > 0.1 MPa) conditions. At sufficiently high temperatures and oxygen fugacities, t he Bi-2212 phase decomposes into a mixture of solid oxides: a Bi-2(Sr, Ca)(2)Cu1O6+/-theta-type (Bi-2201) phase, an alkaline-earth bismuthate Bi9Sr11Ca5Oy-type (Bi-9<(11)under bar>5) phase and CuO. Subsequent re formation of Bi-2212 in pure, flowing oxygen at 0.1 MPa and 860 degree s C has yielded plate-like grains with enhanced 00l texture (as discer ned from X-ray pole figure analyses and electron microscopy). The valu es of oxygen fugacity leading to sub-solidus decomposition and reforma tion of Bi-2212 at 500 to 860 degrees C are given. XRD and SEM analyse s, as well as preliminary critical current measurements of decomposed and reformed Bi-2212 tapes, are presented.