Enhancement of Critical Current Density of Nb₃Al Superconductors by B Doping

Boron (B)-doped Nb3Al superconductors are prepared by mechanical alloying and subsequent sintering process in this work. Then, the critical current density (J(c)) of Nb3Al with different amounts of B doping is studied. In the results, it is shown that J(c) performance of Nb3Al is improved obviously after B doping. The best J(c) value obtained in this work is 2.2 x 10(4 )A cm(-2) (4.2 K, 5 T) for Nb-3(Al0.9B0.1) sample. Furthermore, the mechanism of enhanced J(c) performance for Nb-3(Al0.9B0.1) sample is comprehensively explored. It is found that B doping can significantly enhance the grain connectivity of Nb3Al superconductor, and the active cross-sectional area fraction values increase from 0.11 for the undoped sample to 0.34 for Nb-3(Al0.9B0.1) sample. In addition, the lattice distortion caused by the interstitially dissolved B may also serve as flux pinning centers, which strengthens the flux pinning force of Nb-3(Al0.9B0.1).