Strongly enhanced current densities in Sr0.6 K0.4 Fe2 As2 + Sn superconducting tapes

Abstract

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 (Jc) values. In this work, the superconducting core density of ex-situ Sr0.6 K0.4 Fe 2 As2 + 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 × 104 A/cm 2 in 10T and 4.3 × 10 4 A/cm2 in 14T at 4.2K, respectively. Our tapes also exhibited high upper critical field Hc2 and almost field-independent Jc. These results clearly demonstrate that PIT pnictide wire conductors are very promising for high-field magnet applications.