  We fabricated (Ba,Na)Fe2As2 superconducting wires using the powder-in-tube
method and hot isostatic pressing. By improving powder synthesis processes
compared with previous studies, highly pure raw materials for the wire
fabrication were obtained. The largest transport critical current density (Jc)
reached 40 kAcm-2 at T = 4.2 K under a magnetic field of 100 kOe. This value
exceeds not only the value of transport Jc of the previous (Ba,Na)Fe2As2 wire
but also those of all iron-based superconducting round wires. Improvements of
polycrystalline powder synthesis play a key role for the enhancement of Jc.
Furthermore, it was clarified that higher densification by high-pressure
sintering and the texturing of grains in the core of the wire due to drawing
also increased Jc effectively. Advantages of (Ba,Na)Fe2As2 wires compared with
(Ba,K)Fe2As2 wires are also discussed.
