Influence of bending strain on Bi-2223 tape

The behavior of current-voltage (I-V) characteristics in Bi-2223 AgAgMg sheathed tape at various bending strain has been studied. The measured results were analyzed using the percolation model, and then the variation of critical current density, J(c), has been analyzed. As increasing of bending strain, J(c) in the tape is reduced irreversible way. The irreversible degradation indicates that the J(c) reduction is caused mainly by crack formation. However, if we extract statistic J(c) distribution taking into account the cracking, it can be seen that the value of local J(c) is enlarged in the remained region as the strain is increased. Namely, the pinning strength in the remained region is enlarged as the bending strain is increased. Present analysis allows us to separate the influence on grain connectivity and pinning strength originated from the strain. (C) 2002 Elsevier Science B.V. All rights reserved.