Kinetics and Phase Relation Study of Long Boron Doped Bi-2223 Ag-Sheathed Superconducting Tapes

M. N. Khan；Kh. Zakaullah

Chinese Journal of Physics

46卷3期（2008 / 06 / 01）

338 - 347

英文

The calcined powders of Bi-Sr-Ca-Cu-O (2223) were first characterized by thermal analysis and x-ray diffraction. The powders were then used to fabricate long lengths of flexible Ag-clad 2223 superconductor tape via the powder-in-tube technique. Long lengths of Bi-2223 conductors doped with B were fabricated and the growth of the 2223 phase in the tapes after each heat treatment step was studied. The activation energy and frequency factors for crystallization were determined by non-isothermal Differential Thermal Analysis (DTA), employing different models. The Jc measurements at 77 K showed an increase on silver addition. The elucidation of the phase equilibria in the ceramic core, and especially at the silver interface, is vital if high critical current density (Jc) tapes are to be manufactured. By carefully controlled transport and structural measurements along with changing the annealing temperature, we have been able to ascertain the complex phase equilibria and show the way to future improvements for operation at 77 K.