Improvement of critical current density J c in powder-in-tube rapid heating, quenching and transformation Nb3Al wires by doping with nano-SnO2

Abstract

We prepared Nb3Al superconducting wires doped with nano-size SnO2 (n-SiO2) particles through a multi-time rapid heating and quenching process and investigated their microstructure and superconducting properties. All the samples showed a highly homogeneous A15 Nb3Al phase. Compared with pure Nb3Al, the n-SnO2 doped Nb3Al wires presented a larger ΔT c value and a higher J c value. The best J c at 4.2 K was found in the 1 wt% n-SnO2 doped Nb3Al sample, with 3.37 × 105 A cm−2, 2.55 × 105 A cm−2 and 1.80 × 105 A cm−2 at 8 T, 10 T and 12 T, respectively. These results were an improvement of about 60% compared with pure Nb3Al at the same applied fields. The maximum irreversible field value was obtained in the 1 wt% SnO2-doped Nb3Al wire, with a result of 29.5 T at 4.2 K. The improvement of J c performance in the n-SnO2 doped Nb3Al wires might be attributed to the formation of artificial nanoparticles in the grain, which act as extra effective flux pinning centers.