Transport properties of long monofilamentary Bi(2223) tapes

Long monofilamentary Bi(2223) tapes with j/sub c/ (77 K, 0 Tesla) up to 30000 A/cm/sup 2/ and lengths >1 m have been prepared by cold rolling using the powder in tube method. An optimization of the precursor powders has led to a higher phase purity after the reaction heat treatment. The deformation process has been optimized in order to increase the oxide density and to reduce sausaging effects on the oxide thickness. The transport properties of these tapes have been studied in a wide range of temperatures and magnetic fields. The critical current density values at 77 K and fields of 0.5 T and 1 T parallel to the tape surface are 10000 A/cm/sup 2/ and 5500 A/cm/sup 2/ respectively. At 4.2 K the j/sub c/ value decreases from 1.8/spl middot/10/sup 5/ A/cm/sup 2/ at 0 T to 7/spl middot/10/sup 4/ A/cm/sup 2/ at 15 T. The history dependence of j/sub c/ have also been measured. Several discrepancies have been found between the experimental data and the behavior predicted for a 'weak linked' sample. Transport properties have been studied on small sections cut from the tape in order to investigate the homogeneity of the current distribution.<
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