Improvement of critical current density (Jc) in powder-in-tube (PIT) RHQT Nb3Al wires by doping 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 to pure Nb3Al, the n-SnO2 doped Nb3Al wires presented a larger ΔTc value and higher Jc value. The best Jc at 4.2 K was found in the 1 wt.% n SnO2 doped Nb3Al sample, showing 3.37×105 A/cm2, 2.55×105 A/cm2 and 1.80×105 A/cm2 at 8 T, 10 T and 12 T. These results improved about 60% compared to the pure Nb3Al sample at the same applied field. The maximum Birr 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 Jc performance in the n-SnO2 doped Nb3Al wires might attribute to the formation of artificial nanoparticles in the grain which acted as the extra effective flux pinning centers.