鉄系超電導体1111 系の電子物性とPIT 線材の高特性化

抄録

In a history of superconductors 1911-2017, Fe-based superconductor ReFePnO_1-xF_x (Re: rare earth, Pn: Pnictogen) exhibits relative high superconducting transition temperatures (T_c) ≤ 58 K under ambient pressure. Electron doping by substitution of O^2- with F^- was required for appearance of a superconducting phase with high T_c. The T_c and upper critical field of ReFePnO_1-xF_x are very attractive for applications as superconducting wires and tapes under high magnetic fields, although demonstration of practical superconducting wires is a tough challenge due to the difficulty in controlling the F contents during a processing for ex-situ powder in tube method. In 2017, Zhang et al. reported that iron-based superconducting tapes with Cu sheath showed superconducting electrical current (J_c) ~ 18 kAcm⁻². It is noteworthy that the tapes are sintered at 300°C.