Observation of the Bi,Pb(2223) reaction mechanism and alternative ways of producing tapes with new filament configurations

Investigations on the Bi,Pb(2223) phase formation confirm a mechanism based on nucleation and growth. The same mechanism was found to hold under vario us external conditions: a) in pressed samples, b) in Ag sheathed tapes, c) in air or in reduced oxygen partial pressure and d) with or without the pre sence of Ph, A high temperature neutron diffraction investigation on monofilamentary Bi, Pb(2223) tapes shows that this phase remains stable during the cooling proc ess after reaction, On cooling, an enhancement of the Bi(2212) phase is obs erved, which occurs at the expense of the Other phases, (Sr,Ca)(14)Cu24O41 and Bi(2201), New tape configurations are presented, in view of a) the reduction of aniso tropy ton both, tapes or wires) and b) the reduction of AC losses. These co nfigurations require the use of nonconventional techniques, e.g. two-axis r olling and/or periodic pressing. Using periodic pressing, j(c)(77K,0T) valu es of 35,000 A/cm(2) have been obtained in Bi,Pb(2223) multifilamentary tap es of lengths > 2m.