Comparison of pinning behavior in Bi-2223/Ag tapes with various preparation processing

Transport and magnetization J(c) was measured at various temperatures for d ifferent groups of Bi-2223 tapes, which were prepared by using various proc essing routes (direct cooling, step cooling and pressing). In spite of very different J(c)s in these samples, the field- and temperature-dependent pin ning force can be described well by a unique scaling law except for a lower temperature one, which suggests that the pinning mechanism for these sampl es is approximately the same. It was found that in this system, the main li mitation of the pinning force is due to the plastic deformation of the flux Line lattice in the highest field range. For the direct-cooled sample, the irreversibility field was lower compared to the step-cooled samples, which led to a lower J(c) from both transport and magnetization measurements. Th e electrical connection along the traverse direction was improved in the pr essed samples, which resulted in a larger magnetization J(c). (C) 1999 Publ ished by Elsevier Science B.V. All rights reserved.