Diffusion of Cu into the Ag sheath of BPSCCO tapes

Diffusion studies of (Bi,Pb)(2)Sr2Ca2Cu3O10 (2223) tapes wrapped in Ag show that Cu of the 2223 ceramic diffuse into the Ag sheath during annealing re sulting in a decrease of the Cu content of the ceramic. The diffusion coeff icient has been determined to be 1.8 x 10(-11) cm(2)/s at 815 degrees C. In Ag-Mg alloy the diffusion coefficient appears to be about two orders of ma gnitude faster. Mass balance calculations show that the Cu content of the c eramic decreases by about 8.5% considering an Ag:2223 ceramic ratio of 80:2 0 which is frequently used for 2223 tapes. A diffusion of Bi, Pb, Sr and Ca into Ag has not been observed. (C) 1999 Elsevier Science B.V. All rights r eserved.