BI-2212 PHASE-FORMATION IN MELT-QUENCHED BI2SR2CA1CU2AG0.3OX BY REHEATING IN A VACUUM-SEALED VESSEL

As-cast Ag2O-doped Bi2Sr2Ca1Cu2Ox material was converted into a superc onducting ceramic by reheating in an evacuated and sealed silica-glass tube. The microstructure of the glass-ceramic obtained was characteri zed by electron microscopy. Plate-like crystals of superconducting 221 2 phase, silver metal, and some non-superconducting crystals were prec ipitated by the heat treatment. Metallic silver was not included in th e 2212 phase; it was isolated as metal particles in the matrix phase. It is suggested that the Ag2O doped in Bi2Sr2Ca1Cu2Ox melt acts as a d onor of oxygen, which is requisite for formation of 2212 phase during heat treatment in a vacuum-sealed vessel.