Study on the properties of Bi1.6Pb0.4Sr2Ca2Cu2+xOy superconductors

In this paper we report the results of the study of change in the Cu composition and the effect of annealing time in the Bi1.6Pb0.4Sr2Ca2Cu2+xOy compounds with x=1, 1.9, 2, 2.1 and 2.2. Two sets of samples with sintering time of 48 and 72 It were prepared. The critical current density at 77 K, AC susceptibility, resistivity and powder X-ray diffraction patterns of the samples have been measured. The results show that the phase of 2223 was present in sample x=1.9 with annealing time 72 h and also the optimized J(c) for sample x=2 with annealing time 72 h. Also, the I-V results obey the power law behavior of V=alphaI(beta). (C) 2002 Elsevier Science B.V. All rights reserved.