Comparison of <i>J</i> _c Characteristics Among (Ba,Na)Fe₂As₂ Wires and Tapes Fabricated by Different Methods

In the present study, critical current density (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub>) characteristics and uniformity of (Ba,Na)Fe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>As<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wires and tapes fabricated by different methods and sheath materials are compared. Impurity-free high-quality polycrystalline powders were prepared by two different methods; direct reaction method and precursor method. By optimizing the heat treatment temperature and holding time of precursors, we have succeeded in obtaining high-quality precursor powders. In the case of wire drawing, a rotary swager with an automatic wire feeder is used to prevent sausaging. By using a roller, the wire was further deform into a tape form. In addition to the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> characteristics of (Ba,Na)Fe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>As<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wire and tapes, X-ray characterizations for the evaluation of texturing and uniformity are presented. Finally, a fine and long (Ba,Na)Fe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>As<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wire is fabricated using Monel as an outer sheath material, and its characteristics are presented.