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 Nb 3 Al superconducting wires doped with nano-size SnO 2 (n-SiO 2 ) 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 Nb 3 Al phase. Compared with pure Nb 3 Al, the n-SnO 2 doped Nb 3 Al wires presented a larger Δ T c value and a higher J c value. The best J c at 4.2 K was found in the 1 wt% n-SnO 2 doped Nb 3 Al sample, with 3.37 × 10 5 A cm −2 , 2.55 × 10 5 A cm −2 and 1.80 × 10 5 A cm −2 at 8 T, 10 T and 12 T, respectively. These results were an improvement of about 60% compared with pure Nb 3 Al at the same applied fields. The maximum irreversible field value was obtained in the 1 wt% SnO 2 -doped Nb 3 Al wire, with a result of 29.5 T at 4.2 K. The improvement of J c performance in the n-SnO 2 doped Nb 3 Al wires might be attributed to the formation of artificial nanoparticles in the grain, which act as extra effective flux pinning centers.