Crystallization of glass-ceramic Bi3Sr2Ca2Cu3Oy superconducting system

In this study, the nucleation and the crystallization of the material with nominal composition of Bi3Sr2Ca2Cu3Oδ have been investigated, depending on the heat treatment conditions. It was found that 4 and 8-fold branched nuclei on the samples occurred with increasing the heat treatment temperature. Finally, crystallization occurred with further increase of the temperature. The needle-like crystals (whiskers) perpendicular to the sample surface was formed above 800 °C, which consisted of the Bi-2212 phase. The results clearly showed that the anisotropy of surface tension is the most important parameter in determining the shape of the nucleus.