Hysteresis of the critical current density in YBCO, HBCCO and BSCCO superconducting polycrystals: a comparative study

The hysteresis of the transport critical current of YBa2Cu3O7 - delta (Hg,R e)Ba2Ca2Cu2O8 + delta and (BiPb)(2)Sr2Ca2Cu2O10 + delta polycrystals was st udied. While the first two systems display qualitatively similar hysteretic al patterns, the third one behaves differently. The experimental results ar e interpreted in terms of a phenomenological model which considers the effe cts of the magnetization in the grains on the intergranular weak links as r esponsible for the observed hysteresis. The hysteresis of the transport critical current is discussed on the light of the microstructural features of the samples, concluding that the shape a nd disposition of the grains do not account in a straightforward fashion fo r the differences in the hysteretical behavior. (C) 2000 Published by Elsev ier Science B.V. All rights reserved.