Present status of PIT round wires of 122-type iron-based superconductors

Outstanding characteristics with high T _c and H _c2 and small anisotropy in iron-based superconductors (IBSs) have triggered the development of superconducting wires and tapes using these novel superconductors. In this short article, developments and present status of round wires of 122-type IBSs are reviewed. By introducing hot-isostatic pressing (HIP) technique, J _c in round wires of 122-type IBSs has been improved significantly. Further improvements have been realized by refining the fabrication process of the core material and introducing partial texturing of the wire core. The largest transport J _c for round wires at 4.2 K at self-field and 100 kOe are 2.0x10⁵ A/cm² and 3.8x10⁴ A/cm², respectively. We also compare the J _c characteristics of wires and tapes processed by HIP. (paper)