The Development of Non-Superconducting Phases During Melt Processing of Ag-Sheathed 2212 Tapes

The grain size of the non-superconducting phases [(Sr,Ca)CuO2 (1:1) and a Cu-free phase (~ Bi(Sr,Ca)2Ox)] that coexist with liquid in the melt when melt processing BSCCO2212 were studied as a function of temperature and time. The size of the Cu-free phase on cooling to 870°C, which is the temperature where 2212 begins to form from the liquid on cooling, increases with increasing maximum melt processing temperature, but does not increase significantly with time during the interval needed for melt processing. The size of the 1:1 phase was not significantly affected by temperature up to 910°C, but increased with time. The implications of these observation on developing a melt processing schedule that yields a highly-aligned, homogeneous microstructure are discussed.