Ag2O-doped Bi2Sr2Ca1Cu2Ox superconductors prepared via melt-quenching

Ag2O-doped superconducting Bi2Sr2Ca1Cu2Ox ceramics were prepared by a melt-quenching-reheating method. It is found that the Ag2O-doped, as-cast specimens exhibit superconductivity (Tc = around 80 K) by heat treatment at temperatures around 800 C even in an evacuated and sealed silica glass tube, while the undoped specimens do not and vaporize by the corresponding heat treatment. Conversion of the Ag2O-doped, as-cast specimens into superconducting ceramics when heated in an evacuated vessel is explained in terms of the oxygen donor of Ag2O in the specimen. This finding enables one to fabricate a desired shape of superconducting Bi2Sr2Ca1Cu2Ox ceramics sealed in metals or glasses. The addition of Ag2O to Bi2Sr2Ca1Cu2Ox melt, however, had deleterious influences on the superconducting properties (Tc and Jc) of the resultant ceramics when obtained by heat treatment in air