Microstructure and electrical properties of Bi1.8Pb0.4Sr2Ca2.1Cu3Ox tapes with CeO2 ceramic barriers

The AC losses in multifilamentary tapes can be reduced mainly by insulating barriers (ceramics or alloys) and by twisting the filaments. We have prepa red multifilamentary Bi1.8Pb0.4Sr2Ca2.1Cu3Ox (BSCCO)/Ag tapes with the "pow der-in -tube" process where the single filaments were surrounded with a cer amic layer. The microstructure and the electrical properties of tapes with CeO2 barriers and without barriers will be compared. All tapes with ceramic barriers have broader transition to superconductivity and lower critical c urrent densities than pure Ag tapes. We have found a melt-forming reaction between the CeO2 barriers and the BSCCO filaments during heat treatment, re sulting in a drastic jc degradation. The problem of interaction is more pro nounced in the case of tapes with more filaments. Due to the thinner Ag int erlayers in these tapes, a direct contact of BSCCO and the insulating ceram ic by cracks or spikes cannot be avoided during processing. (C) 2001 Elsevi er Science B.V. All rights reserved.