MELTING OF BI-2212 UNDER CONTROLLED OXYGEN PARTIAL PRESSURES WITH SILVER

The solidus temperature T-solidus of Bi2Sr2CaCu2Ox (Bi-2212) is decrea sed from 893 degrees C to 880 degrees C and further down to 834 degree s C when the oxygen partial pressure of the atmosphere is changed from pO(2) = 1 atm to 0.21 atm and further to 0.001 atm. Silver additions to the superconductor exceeding 2 wt% lower T-solidus by UP to 25 K in a pure oxygen atmosphere. The weight loss during melting, which is re lated to oxygen release, is highest at low oxygen partial pressures an d can be reduced by silver additions due to increased oxygen solubilit y of the Bi-2212 melt in presence of dissolved silver. The experimenta l results are compared with thermodynamic data of the Bi-Sr-Ca-Cu-O sy stem.