Introducing nano-scale MgO particles into RHQT Nb3Al superconducting wires to significantly improve the critical current density

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This research introduced nano-scale particles into the RHQT Nb3Al superconducting wires, which was confirmed by TEM that nanoparticles with size of 5–25 nm distributed in the wires and might act as the extra flux pinning centers. The precursor wires were fabricated by powder in tube process with nano-sized MgO (n-MgO) doped in the raw powder. Uniform microstructure and chemical composition were obtained in the superconducting wires. Besides nanoparticles, high density stacking faults with spacing of 5–20 nm were observed in the Nb3Al superconducting wire, which acted as the dominant flux pinning centers. It had great importance that nanoparticles were introduced into the RHQT Nb3Al wires and combined with the high density stacking faults to significantly improve the critical current density (Jc) of the wires. The magnetic Jc results of 1 wt% n-MgO doped Nb3Al wire were about twice of the non-doped sample, corresponding to Jc values of 3.18 × 105 A/cm2, 2.38 × 105 A/cm2 and 1.72 × 105 A/cm2 at 4.2 K and 8 T, 10 T and 12 T.