High performance Fe-cladded MgB2 taps were prepared by the in situ powder-in-tube method utilizing very cheap stearic acid (C18 H36O2) as dopants. The amount of stearic acid was varied from 0 to 30 wt%. We found that a significant enhancement of Jc, Hirr, and Hc2 in comparison with undoped samples was easily achieved. At 4.2 K, the transport Jc for the best doped tapes (10 wt%) reached 2 × 104 A/ cm2 at 10 T and 3.7 × 103 A/cm2 at 14 T, respectively, an order of magnitude higher than for the pure tapes. In particular, at 20 K, the irreversibility field of the 10 wt% doped tape was around 10 T, which is comparable to the upper critical field of the commercial NbTi at 4.2 K. The results demonstrate great potential of MgB2 tapes for superconducting magnets.
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