Sugar Coating of Boron Powder for Efficient Carbon Doping of MgB_2 with Enhanced Current-Carrying Performance

摘要

The second boom in superconductivity during the last two decades has been powered up by the discovery of MgB_2 having the transition temperature (T_c) of 39 K as well as a strong market potential for applications. The strongest impact on the development of this superconductor has been made by the discovery of the significant enhancement of the critical current density (J_c) as a function of the applied magnetic field (B_a) that results from SiC nanodoping. Since then, a large variety of dopants have been attempted in order to achieve or improve on the attained enhancement. In the vast majority of these doping works the nanodopants have been introduced via a solid-state reaction; however, an important challenge is achieving homogeneity between a small amount of nanoadditives and matrix materials, because any dry mixing poses the major problem of nanoparticle agglomeration.