Superconducting properties of rapidly heated and quenched Nb3Ga wires

Stoichiometric Nb₃Ga with good long range ordering shows a high T_c above 20 K and a high H_c2(4.2 K) above 30 T. However, high J_c had not yet been reported for any Nb₃Ga fabricated through various methods, which was preventing the development of practical Nb₃Ga conductors in the last 30 years. Recently we could overcome the problem through a promising combination of RHQ (rapid heating and quenching) treatment and microcomposite precursor wire of Nb and NbGa₃. Nb₃Ga layers were formed directly through the RHQ treatment. Post annealing at 600-800°C was very effective in improving the superconducting properties of the Nb₃Ga wire. The best values of T_c and B_c2(4.2 K) of 19.7 K and 32 T were obtained, respectively. In addition the J_c(4.2 K) values of Nb₃Ga layer at 20 T, 23 T, and 25 T were 370 A/mm², 250 A/mm² and 160 A/mm², respectively. These critical values are much higher than those of the commercialized (Nb,Ti)₃ Sn wire made through a bronze route.