Effects of Ag, Ag2O and AgNO3 additions in (Bi,Pb)-2223/Ag powder-in-tube tapes

The effects of Ag powder, Ag2O and AgNO3 on phase evolution, microstructure and critical current density (J(c)) in Ag sheathed powder-in-tube (PIT) ta pes have been studied. In contrast to the results reported for bulk BPSCCO, the Ag additions in tapes deteriorate the rate of high-T-c phase formation , ultimate high-T-c phase fraction and J(c) to different extents depending on the form of Ag additive. In the case of Ag powder and Ag2O-added tapes, the deteriorations are severe while AgNO3 deteriorates them only to a lower extent. Microstructural examination of the Ag-added tapes shows larger gra in growth in all the Ag-added tapes with the Ag particle size depending on the size and form of the Ag additive. It has been shown that in BPSCCO/Ag t apes the Ag available in the form of sheath is sufficient to impart the ben eficial effects of Ag addition found in bulk BPSCCO system and addition of Ag in any form apart from the sheath only deteriorates the rate of high-T-c phase formation and J(c). (C) 1999 Elsevier Science B.V. All rights reserv ed.