Strongly enhanced current densities in Sr0.6K0.4Fe2As2 + Sn superconducting tapes

Improving transport current has been the primary topic for practical application of superconducting wires and tapes. However, the porous nature of powder-in-tube (PIT) processed iron-based tapes is one of the important reasons for low critical current density (J(c)) values. In this work, the superconducting core density of ex-situ Sr0.6K0.4Fe2As2 + Sn tapes, prepared from optimized precursors, was significantly improved by employing a simple hot pressing as an alternative route for final sintering. The resulting samples exhibited optimal critical temperature (T-c), sharp resistive transition, small resistivity and high Vickers hardness (Hv) value. Consequently, the transport J(c) reached excellent values of 5.1 x 10(4) A/cm(2) in 10 T and 4.3 x 10(4) A/cm(2) in 14 T at 4.2 K, respectively. Our tapes also exhibited high upper critical field H-c2 and almost field-independent J(c). These results clearly demonstrate that PIT pnictide wire conductors are very promising for high-field magnet applications.