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

Abstract

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 ^(o) C for 1 h at ambient pressure. SEM shows a highly dense core with a large grain size of 100 micron. The Fe clad tape shows a sharp transition with transition width of 0.2 K and Tc0 at 37.5 K. We have achieved the highest transport critical current reported so far at 1.6 times 10^(4) A/cm^2 for both 29.5 K in 1 Tesla and 33 K in null field. R-T and critical current were also measured for fields perpendicular and parallel to the tape plane. The iron cladding shielded on the core from the applied external field, with the shielding being less effective for the field in the tape plane. Fe cladding may be advantageous for some applications as it could reduce the effects of both the self-field and external fields.