Enhancement of the critical current density and the irreversibility field in maleic anhydride doped MgB2 based tapes

A significant enhancement of J(c), H-irr, and H-c2 in MgB2 tapes has been achieved by using maleic anhydride (C4H2O3) as dopants. MgB2 tape samples with 0 up to 30 wt % C4H2O3 added were prepared by an in situ processed powder-in-tube method. Compared to the pure tapes, J(c) for the 10 wt % C4H2O3 doped samples was improved by more than an order of magnitude in high fields up to 18 T. At 4.2 K, the transport J(c) for the 10 wt % doped samples reached 1.08x10(4), 5.42x10(3), and 2.18x10(3) A/cm(2) at 12, 14, and 16 T, respectively, and were better than those of the best MgB2/Fe tapes reported by far. Furthermore, the H-irr for the 10 wt % doped sample reached 9.6 T at 20 K, which was comparable to that of NbTi at 4.2 K. The improvement of the superconducting properties in doped tapes can be attributed to the increase of H-c2 and the grain size refinement by C4H2O3 doping. (c) 2007 American Institute of Physics.