S. Nezir et al., Effect of annealing period on the resistive transitions and AC losses in aBi1.6Pb0.4Sr2Ca3Cu4O12 superconductor fabricated by a wet technique, J ALLOY COM, 302(1-2), 2000, pp. 235-238
We estimated the irreversibility lines from the resistive-superconducting t
ransition in DC magnetic fields up to 1 T for the Bi1.6Pb0.4Sr2Ca3Cu4O12 su
perconducting samples prepared by liquid ammonium nitrate with the same hea
t treatment but 25 h and 200 h of annealing time. Increasing the annealing
time from 25 h to 200 h at 840 degrees C shifted the irreversibility temper
ature to a higher temperature. A non-linear Arrhenius plot of the resistive
tail has been found. The activation energy obtainable from Arrhenius plots
seems to be non-linear temperature dependent. The peak temperature T-p, in
the imaginary part of the AC susceptibility seems to be shifted to a highe
r temperature by nearly the same amount as the shift in irreversibility tem
perature with increasing annealing time. Temperature variation of the criti
cal current density extracted from the theoretical calculation of matrix su
sceptibility and irreversibility line obey the same power law dependence of
(1 - T/T-c)(n), where n = 2.7 and 2.5 for the 25-h and 200-h samples, resp
ectively. (C) 2000 Elsevier Science S.A. All rights reserved.