Preparation and Properties of Superconducting Glass Ceramics Based on the Bi-Sr-Ca-Cu-O System

We prepared many bulk glasses in compositions around BiSrCaCu2Ox using the conventional melt quenching method and examined superconducting properties of the glass ceramics obtained. It was found that the compositions in the Bi-Sr-Ca-Cu-O system had a great tendency to form a glass and Bi2O3 played an important role in the glass formation. The glass transition and crystallization temperatures for the glasses of BixSrCaCu2Ow (x=1.2-3) were in the range between 425° and 370°C and in the range between 450° and 430°C, respectively and both values tended to decrease with increasing Bi2O3 content. The ratio of SrO and CaO was also important for the glass formation and the coexistence of SrO and CaO was needed to form a glass. Many glasses became superconducting glass ceramics with the Tc values of around 75K by annealing at 820°C for 40h air.