Development of Doped ${\rm MgB}_{2}$ Wires and Tapes for Practical Applications

Abstract

Abstract-A review of current developments in the study of chemical doping effect on the superconducting properties of MgB 2 wires and tapes is presented, based on the known literature data and our own results. The critical current density of MgB 2 can be improved through various kinds of dopants. Among these dopants, doping with carbon-containing materials seems to be the most effective way to improve the J c performance. The doping effect of carbon in different forms and carbon-based compounds such as SiC, nano-C, metal carbides, as well as aromatic hydrocarbon and carbohydrate on the J c -B characteristics of MgB 2 was discussed in detail. The C can be incorporated into the MgB 2 crystal lattice by replacing boron, and thus BB c2 is significantly enhanced due to selective tuning of impurity scattering of the π and σ bands in the two-band MgB 2 . Besides the efforts of increasing B c2 B by carbon doping, the fine grain size and nano-size inclusions caused by doping would create many flux pinning centres improving the J c -B property of MgB 2 . Based on these considerations, we suggested some principles for the selection of dopants.