Formation and growth of Bi-2223 phase in Bi-2223/Ag and Bi-2223/AgAu tapes

Mono-filament Bi-2223/Ag and Bi-2223/AgAu tapes were fabricated by power-in tube technique. The Bi-2223 phase formation temperature and content of Bi-2223/Ag and Bi-2223/AgAu tapes were analyzed first. To have a quantitative understanding of growth process of Bi-2223 grains during the sintering process, the length and thickness of Bi-2223 platelets were measured. It is found that the growth rate in the length direction of Bi-2223 platelets was two orders of magnitude higher than that in the thickness direction and the Bi-2223 grains had same growth rate in the length direction for Bi-2223/Ag and Bi-2223/AgAu tape, but growth rate in the thickness direction was different. When sintering time reached 10 h, the average platelet thickness of Bi-2223/Ag and Bi-2223/AgAu tapes were 0.3 and 0.23 μm, respectively. This will bring about the difference in the phase content of Bi-2223, which is the key to affecting the current-carrying performance of the tape. The above results provided insightful information to understand both Bi-2223 phase growth of Bi-2223/AgAu tape and to improve its current-carrying property.