TEM study on the effects of intermediate quenching on some defects in highJ(c) Bi-2223 tapes

The microstructure of the 69-filamentary Bi-2223 tapes with high J(c) of 51 000 A/cm(2) at 77 K and self-field has been studied by using the transmiss ion electron microscopy (TEM) method. The tapes were treated by two steps s intering with intermediate quenching (IQ) and pressing [S.X. Dou, R. Zeng, T.P. Beals, H.K. Liu, Physica C 303 (1998) 21]. The diversified defects in the grains or colonies that influence the properties of the tapes were thor oughly observed by TEM. IQ is an effective method to promote the healing of the cracks, prevent the forming of the large secondary phases, and affects the critical current density of the tapes. (C) 2000 Elsevier Science B.Y. All rights reserved.