Phase formation mechanism and properties of Ag-sheathed (Bi,Pb)-2223 tapes prepared by two-powder method

The effects of two-powder method on the J(c) properties were investigated through the microstructure and c-axis orientation observations. Three kinds of Ag-sheathed (Bi,Pb)(2)Sr2Ca2Cu3ON tapes from one-powder and two-powder precursors were fabricated. The micro structures, phase constructions and J(c) properties were compared in these tapes. The tapes from two-powder and one-powder calcined at 780 degreesC precursors show good J(c) values compared to the samples from one-powder calcined at 825 degreesC. No clear difference in microstructures and c-axis orientations were not observed in the final tapes, while the high Jc samples had large amount of non-reacted residual phases before the second sintering step. This suggests that the residual phases may promote the improvement of the grain connectivity during second sintering step to lead the high Jc values. (C) 2003 Elsevier B.V. All rights reserved.