Effect of CaCuO2 addition to precursors on I-c and I-c-H behaviours of Bi-2223/Ag tapes fabricated by the two-powder process

Precursors prepared by mixing (Bi,Pb)-2212 and CaCuO2 have been successfull y used in the synthesis of high quality Bi-2223/Ag tapes. The effect of exc ess CaCuO2, over a range between -5 and 15 at.%, on the properties of monof ilamentary Bi-2223/Ag tapes has been studied. It was found that the maximum value of I-c was 23 A at 77 K for a sample doped with 10 at.% CaCuO2 but t hat too much doping (e.g. 15 at.% addition) will decrease the I-c of a samp le significantly due to a higher level of the impurity phase. However, the observed I-c-H behaviour for tape with 15 at.0/o CaCuO2 addition was better than what was observed for undoped samples and for samples with relatively less CaCuO2 dopant, indicating that excess CaCuO2 enhanced the flux pinnin g. Based on the results obtained from monofilamentary samples, 37-filamenta ry tapes with and without CaCuO2 addition were fabricated. The I-c of the 5 at.% CaCuO2-doped sample was 45 A at 77 K, whereas it was 36 A for the und oped sample. (C) 2001 Elsevier Science B.V. All rights reserved.