High-transport critical current density above 30 K in pure Fe-clad MgB2 tape

Fe-clad MgB2 long tapes have been fabricated using a powder-in-tube technique. An Mg + 2B mixture was used as the central conductor core and reacted in situ to form MgB2. The tapes were sintered in pure Ar at 800 degreesC for 1 h at ambient pressure. SEM shows a highly dense core with a large grain size of 100 mum. The Fe-clad tape shows a sharp transition with transition width of DeltaT(c) of 0.2 K and a T-c0 of 37.5 K. We have achieved the highest transport critical current reported so far at 1.7 x 10(4) A/cm(2) for both 29.5 K in 1 T and 33 K in zero applied field. Resistivity temperature dependence and transport critical current were also measured in magnetic fields applied perpendicular and parallel to the tape plane. Not only is the use of an Fe sheath necessary for the successful processing of in situ reacted powder-in-tube MgB2, it confers on the finished wire the additional benefit of magnetic screening. (C) 2001 Elsevier Science B.V. All rights reserved.