Fabrication of FeSe superconducting tapes with high-energy ball milling aided PIT process

• The diffusion between Fe and Se particles was enhanced with HEBM process.
• The formation of non-superconducting δ-FeSe phase was successfully avoided.
• FeSe superconducting tapes with higher current capacity was achieved.

Fe sheathed FeSe Superconducting tapes with high superconducting phase ratio and high critical current density were prepared with powder in tube (PIT) process combining with a high energy ball milling (HEBM) aided sintering process. The introduction of HEBM process not only assured the atomic uniformity of precursor powders, but greatly shortened the diffusion distance between Fe and Se atoms from micron meters to atomic level, thus effectively avoided the formation of non-superconducting hexagonal δ-FeSe phase. Due to the absence of δ-FeSe phase within β-FeSe grain boundaries, the current transport properties of FeSe tapes were greatly enhanced. The FeSe superconducting tapes with the critical current density of ∼340 A cm−2 at 4.2 K self field was obtained with ex-situ PIT process combining with HEBM process and a sintering temperature of 800 °C.