Influence of extra magnesium on the Nb–B interface and superconducting properties of MgB2/Nb tapes

Abstract Effects of extra Mg additions on the Nb–B interface and the superconducting properties of mono-core MgB 2 /Nb/Cu tapes were investigated. Four Mg 1+ x B 2 /Nb/Cu tape samples were prepared by standard in situ PIT method ( x  = 0, 0.03, 0.05, 0.10). For maintaining the superconducting properties, the extra Mg is supposed to prevent the Nb–B diffusion, which is the main cause of decline in superconducting properties of Nb sheathed MgB 2 tapes. And it has been proved that a suitable amount of Mg addition did play a positive role in slowing down the Nb–B diffusion to some degree on one hand. And the superconducting properties also show some improvements. While over sufficient Mg addition would accelerate the formation of the Nb–B diffusion layer on the other hand. According to the experimental results, the suitable amount of Mg addition should be between x  = 0.03 and 0.05 depending on the different sintering temperatures.