CORRELATION BETWEEN REACTION-KINETICS OF THE BI(PB)-2223 PHASE AND CRITICAL-CURRENT DENSITY IN BI(PB)-2223 AG TAPES/

The correlation between reaction kinetics of the Bi(Pb)-2223 phase and critical current density in Bi(Pb)-2223/Ag tapes has been analysed. I t has been found that a slow formation rate of the 2223 phase allows a higher J(c) value, while a faster formation rate of the 2223 phase co rresponds to a lower J(c) value. A mechanism for the Bi(Pb)-2223 forma tion has been proposed, in which two reaction routes control the forma tion of the 2223 phase. One is a liquid-assisted nucleation and growth ; the other is an intercalation process. The reaction rates of the two routes depend on the phase assemblage of the precursor powder, determ ined by the start composition and calcination conditions. The new mech anism has successfully described the correlation between the reaction kinetics and critical current density in Bi(Pb)-2223/Ag tapes and can be used as a guide for preparing the precursor powder for Bi(Pb)-2223/ Ag tapes.