S. Celebi et al., Frequency dependence of the intergranular AC loss peak in a high-T-c Bi-(Pb)-Sr-Ca-Cu-O bulk superconductor, PHYSICA C, 309(1-2), 1998, pp. 131-137
We have performed AC susceptibility measurements as a function of temperatu
re; frequency and AC field amplitude on a rectangular bar shaped high-tempe
rature superconductor with nominal composition of Bi1.8.4Pb0.34Sr1.91Ca2.03
Cu3.06O10 prepared by the liquid ammonium nitrate method. We have observed
that as the frequency (AC field amplitude) increases, the intra- and interg
ranular AC loss peaks move higher (lower) temperature, which indicates that
AC losses are due to both hysteretic bulk pinning losses and viscous (flux
flow) losses. M-H curves exhibit a hysteresis which is similar to that of
hysteretic superconductors. Activation energy at the grain boundary is extr
acted from the loss peak at some selected AC fields. Experimental results a
re qualitatively discussed in the framework of the critical state model (CS
M). (C) 1998 Elsevier Science B.V. All rights reserved.